diff --git a/CHANGELOG.md b/CHANGELOG.md
index 039968ce1d74..b02a9d22fc9b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -74,6 +74,7 @@
 - `[jest-repl]`: Migrate to TypeScript ([#8000](https://github.com/facebook/jest/pull/8000))
 - `[jest-validate]`: Migrate to TypeScript ([#7991](https://github.com/facebook/jest/pull/7991))
 - `[docs]`: Update CONTRIBUTING.md to add information about running jest with `jest-circus` locally ([#8013](https://github.com/facebook/jest/pull/8013)).
+- `[@jest/core]`: Migrate to TypeScript ([#7998](https://github.com/facebook/jest/pull/7998))
 
 ### Performance
 
diff --git a/packages/jest-changed-files/src/index.ts b/packages/jest-changed-files/src/index.ts
index 9d31072168e6..0b8c802e915d 100644
--- a/packages/jest-changed-files/src/index.ts
+++ b/packages/jest-changed-files/src/index.ts
@@ -15,6 +15,8 @@ import hg from './hg';
 
 type RootPromise = ReturnType<SCMAdapter['getRoot']>;
 
+export {ChangedFiles, ChangedFilesPromise} from './types';
+
 function notEmpty<T>(value: T | null | undefined): value is T {
   return value != null;
 }
diff --git a/packages/jest-changed-files/src/types.ts b/packages/jest-changed-files/src/types.ts
index 3d040a6c49dd..e45c07d3eb37 100644
--- a/packages/jest-changed-files/src/types.ts
+++ b/packages/jest-changed-files/src/types.ts
@@ -14,12 +14,10 @@ export type Options = {
   includePaths?: Array<Config.Path>;
 };
 
-type ChangedFiles = Set<Config.Path>;
-export type Repos = {git: ChangedFiles; hg: ChangedFiles};
-export type ChangedFilesPromise = Promise<{
-  repos: Repos;
-  changedFiles: ChangedFiles;
-}>;
+type Paths = Set<Config.Path>;
+export type Repos = {git: Paths; hg: Paths};
+export type ChangedFiles = {repos: Repos; changedFiles: Paths};
+export type ChangedFilesPromise = Promise<ChangedFiles>;
 
 export type SCMAdapter = {
   findChangedFiles: (
diff --git a/packages/jest-core/package.json b/packages/jest-core/package.json
index adc6256996b9..df5b1957d691 100644
--- a/packages/jest-core/package.json
+++ b/packages/jest-core/package.json
@@ -4,6 +4,7 @@
   "version": "24.1.0",
   "main": "build/jest.js",
   "dependencies": {
+    "@jest/types": "^24.1.0",
     "@jest/reporters": "^24.1.0",
     "@jest/transform": "^24.1.0",
     "ansi-escapes": "^3.0.0",
@@ -24,7 +25,7 @@
     "jest-watcher": "^24.0.0",
     "micromatch": "^3.1.10",
     "p-each-series": "^1.0.0",
-    "pirates": "^4.0.0",
+    "pirates": "^4.0.1",
     "realpath-native": "^1.1.0",
     "rimraf": "^2.5.4",
     "strip-ansi": "^5.0.0"
diff --git a/packages/jest-core/src/FailedTestsCache.js b/packages/jest-core/src/FailedTestsCache.ts
similarity index 51%
rename from packages/jest-core/src/FailedTestsCache.js
rename to packages/jest-core/src/FailedTestsCache.ts
index 73c0970e1646..f0bb0fde064d 100644
--- a/packages/jest-core/src/FailedTestsCache.js
+++ b/packages/jest-core/src/FailedTestsCache.ts
@@ -3,45 +3,49 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {Test} from 'types/TestRunner';
-import type {TestResult} from 'types/TestResult';
-import type {GlobalConfig} from 'types/Config';
+import {Test} from 'jest-runner';
+import {Config, TestResult} from '@jest/types';
+
+type TestMap = {[key: string]: {[key: string]: boolean}};
 
 export default class FailedTestsCache {
-  _enabledTestsMap: ?{[key: string]: {[key: string]: boolean}};
+  private _enabledTestsMap?: TestMap;
 
   filterTests(tests: Array<Test>): Array<Test> {
-    if (!this._enabledTestsMap) {
+    const enabledTestsMap = this._enabledTestsMap;
+
+    if (!enabledTestsMap) {
       return tests;
     }
-    // $FlowFixMe
-    return tests.filter(testResult => this._enabledTestsMap[testResult.path]);
+    return tests.filter(testResult => enabledTestsMap[testResult.path]);
   }
 
-  setTestResults(testResults: Array<TestResult>) {
+  setTestResults(testResults: Array<TestResult.TestResult>) {
     this._enabledTestsMap = (testResults || [])
       .filter(testResult => testResult.numFailingTests)
-      .reduce((suiteMap, testResult) => {
+      .reduce<TestMap>((suiteMap, testResult) => {
         suiteMap[testResult.testFilePath] = testResult.testResults
           .filter(test => test.status === 'failed')
-          .reduce((testMap, test) => {
-            testMap[test.fullName] = true;
-            return testMap;
-          }, {});
+          .reduce(
+            (testMap, test) => {
+              testMap[test.fullName] = true;
+              return testMap;
+            },
+            {} as {[name: string]: true},
+          );
         return suiteMap;
       }, {});
+
     this._enabledTestsMap = Object.freeze(this._enabledTestsMap);
   }
 
-  updateConfig(globalConfig: GlobalConfig): GlobalConfig {
+  updateConfig(globalConfig: Config.GlobalConfig): Config.GlobalConfig {
     if (!this._enabledTestsMap) {
       return globalConfig;
     }
-    const newConfig: GlobalConfig = {...globalConfig};
+    const newConfig: Config.GlobalConfig = {...globalConfig};
     newConfig.enabledTestsMap = this._enabledTestsMap;
     return Object.freeze(newConfig);
   }
diff --git a/packages/jest-core/src/ReporterDispatcher.js b/packages/jest-core/src/ReporterDispatcher.ts
similarity index 69%
rename from packages/jest-core/src/ReporterDispatcher.js
rename to packages/jest-core/src/ReporterDispatcher.ts
index 6e492dcd571b..b36299aa1cb9 100644
--- a/packages/jest-core/src/ReporterDispatcher.js
+++ b/packages/jest-core/src/ReporterDispatcher.ts
@@ -3,23 +3,15 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {Context} from 'types/Context';
-import type {Reporter, Test} from 'types/TestRunner';
-import type {TestResult, AggregatedResult} from 'types/TestResult';
-import type {ReporterOnStartOptions} from 'types/Reporters';
-
-export type RunOptions = {|
-  estimatedTime: number,
-  showStatus: boolean,
-|};
+import {TestResult} from '@jest/types';
+import {Test} from 'jest-runner';
+import {Context} from 'jest-runtime';
+import {Reporter, ReporterOnStartOptions} from './types';
 
 export default class ReporterDispatcher {
-  _disabled: boolean;
-  _reporters: Array<Reporter>;
+  private _reporters: Array<Reporter>;
 
   constructor() {
     this._reporters = [];
@@ -37,8 +29,8 @@ export default class ReporterDispatcher {
 
   async onTestResult(
     test: Test,
-    testResult: TestResult,
-    results: AggregatedResult,
+    testResult: TestResult.TestResult,
+    results: TestResult.AggregatedResult,
   ) {
     for (const reporter of this._reporters) {
       reporter.onTestResult &&
@@ -52,13 +44,19 @@ export default class ReporterDispatcher {
     }
   }
 
-  async onRunStart(results: AggregatedResult, options: ReporterOnStartOptions) {
+  async onRunStart(
+    results: TestResult.AggregatedResult,
+    options: ReporterOnStartOptions,
+  ) {
     for (const reporter of this._reporters) {
       reporter.onRunStart && (await reporter.onRunStart(results, options));
     }
   }
 
-  async onRunComplete(contexts: Set<Context>, results: AggregatedResult) {
+  async onRunComplete(
+    contexts: Set<Context>,
+    results: TestResult.AggregatedResult,
+  ) {
     for (const reporter of this._reporters) {
       reporter.onRunComplete &&
         (await reporter.onRunComplete(contexts, results));
@@ -67,7 +65,7 @@ export default class ReporterDispatcher {
 
   // Return a list of last errors for every reporter
   getErrors(): Array<Error> {
-    return this._reporters.reduce((list, reporter) => {
+    return this._reporters.reduce<Array<Error>>((list, reporter) => {
       const error = reporter.getLastError && reporter.getLastError();
       return error ? list.concat(error) : list;
     }, []);
diff --git a/packages/jest-core/src/SearchSource.js b/packages/jest-core/src/SearchSource.ts
similarity index 70%
rename from packages/jest-core/src/SearchSource.js
rename to packages/jest-core/src/SearchSource.ts
index bba5158d00e6..5c1992b55d94 100644
--- a/packages/jest-core/src/SearchSource.js
+++ b/packages/jest-core/src/SearchSource.ts
@@ -3,52 +3,55 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {Context} from 'types/Context';
-import type {Glob, GlobalConfig, Path} from 'types/Config';
-import type {Test} from 'types/TestRunner';
-import type {ChangedFilesInfo} from 'types/ChangedFiles';
-
 import path from 'path';
 import micromatch from 'micromatch';
+import {Context} from 'jest-runtime';
+import {Config} from '@jest/types';
+import {Test} from 'jest-runner';
+import {ChangedFiles} from 'jest-changed-files';
 import DependencyResolver from 'jest-resolve-dependencies';
 import {escapePathForRegex} from 'jest-regex-util';
 import {replaceRootDirInPath} from 'jest-config';
 import {buildSnapshotResolver} from 'jest-snapshot';
 import {replacePathSepForGlob, testPathPatternToRegExp} from 'jest-util';
+import {
+  Stats,
+  TestPathCases,
+  TestPathCasesWithPathPattern,
+  TestPathCaseWithPathPatternStats,
+} from './types';
+
+export type SearchResult = {
+  noSCM?: boolean;
+  stats?: Stats;
+  collectCoverageFrom?: Set<string>;
+  tests: Array<Test>;
+  total?: number;
+};
 
-type SearchResult = {|
-  noSCM?: boolean,
-  stats?: {[key: string]: number},
-  collectCoverageFrom?: Set<string>,
-  tests: Array<Test>,
-  total?: number,
-|};
-
-export type TestSelectionConfig = {|
-  input?: string,
-  findRelatedTests?: boolean,
-  onlyChanged?: boolean,
-  paths?: Array<Path>,
-  shouldTreatInputAsPattern?: boolean,
-  testPathPattern?: string,
-  watch?: boolean,
-|};
+export type TestSelectionConfig = {
+  input?: string;
+  findRelatedTests?: boolean;
+  onlyChanged?: boolean;
+  paths?: Array<Config.Path>;
+  shouldTreatInputAsPattern?: boolean;
+  testPathPattern?: string;
+  watch?: boolean;
+};
 
 type FilterResult = {
-  test: string,
-  message: string,
+  test: string;
+  message: string;
 };
 
-const globsToMatcher = (globs: ?Array<Glob>) => {
+const globsToMatcher = (globs?: Array<Config.Glob> | null) => {
   if (globs == null || globs.length === 0) {
     return () => true;
   }
 
-  return path =>
+  return (path: Config.Path) =>
     micromatch.some(replacePathSepForGlob(path), globs, {dot: true});
 };
 
@@ -57,10 +60,11 @@ const regexToMatcher = (testRegex: Array<string>) => {
     return () => true;
   }
 
-  return path => testRegex.some(testRegex => new RegExp(testRegex).test(path));
+  return (path: Config.Path) =>
+    testRegex.some(testRegex => new RegExp(testRegex).test(path));
 };
 
-const toTests = (context, tests) =>
+const toTests = (context: Context, tests: Array<Config.Path>) =>
   tests.map(path => ({
     context,
     duration: undefined,
@@ -68,15 +72,10 @@ const toTests = (context, tests) =>
   }));
 
 export default class SearchSource {
-  _context: Context;
-  _rootPattern: RegExp;
-  _testIgnorePattern: ?RegExp;
-  _testPathCases: {
-    roots: (path: Path) => boolean,
-    testMatch: (path: Path) => boolean,
-    testRegex: (path: Path) => boolean,
-    testPathIgnorePatterns: (path: Path) => boolean,
-  };
+  private _context: Context;
+  private _rootPattern: RegExp;
+  private _testIgnorePattern: RegExp | null;
+  private _testPathCases: TestPathCases;
 
   constructor(context: Context) {
     const {config} = context;
@@ -99,12 +98,21 @@ export default class SearchSource {
     };
   }
 
-  _filterTestPathsWithStats(
+  private _filterTestPathsWithStats(
     allPaths: Array<Test>,
     testPathPattern?: string,
   ): SearchResult {
-    const data = {
-      stats: {},
+    const data: {
+      stats: Stats;
+      tests: Array<Test>;
+      total: number;
+    } = {
+      stats: {
+        roots: 0,
+        testMatch: 0,
+        testPathIgnorePatterns: 0,
+        testRegex: 0,
+      },
       tests: [],
       total: allPaths.length,
     };
@@ -112,17 +120,21 @@ export default class SearchSource {
     const testCases = Object.assign({}, this._testPathCases);
     if (testPathPattern) {
       const regex = testPathPatternToRegExp(testPathPattern);
-      testCases.testPathPattern = path => regex.test(path);
+      (testCases as TestPathCasesWithPathPattern).testPathPattern = (
+        path: Config.Path,
+      ) => regex.test(path);
+      (data.stats as TestPathCaseWithPathPatternStats).testPathPattern = 0;
     }
 
-    const testCasesKeys = Object.keys(testCases);
+    const testCasesKeys = Object.keys(testCases) as Array<keyof Stats>;
     data.tests = allPaths.filter(test =>
       testCasesKeys.reduce((flag, key) => {
+        const {stats} = data;
         if (testCases[key](test.path)) {
-          data.stats[key] = ++data.stats[key] || 1;
+          stats[key] = stats[key] === undefined ? 1 : stats[key] + 1;
           return flag && true;
         }
-        data.stats[key] = data.stats[key] || 0;
+        stats[key] = stats[key] || 0;
         return false;
       }, true),
     );
@@ -130,25 +142,25 @@ export default class SearchSource {
     return data;
   }
 
-  _getAllTestPaths(testPathPattern: string): SearchResult {
+  private _getAllTestPaths(testPathPattern?: string): SearchResult {
     return this._filterTestPathsWithStats(
       toTests(this._context, this._context.hasteFS.getAllFiles()),
       testPathPattern,
     );
   }
 
-  isTestFilePath(path: Path): boolean {
-    return Object.keys(this._testPathCases).every(key =>
-      this._testPathCases[key](path),
-    );
+  isTestFilePath(path: Config.Path): boolean {
+    return (Object.keys(this._testPathCases) as Array<
+      keyof TestPathCases
+    >).every(key => this._testPathCases[key](path));
   }
 
-  findMatchingTests(testPathPattern: string): SearchResult {
+  findMatchingTests(testPathPattern?: string): SearchResult {
     return this._getAllTestPaths(testPathPattern);
   }
 
   findRelatedTests(
-    allPaths: Set<Path>,
+    allPaths: Set<Config.Path>,
     collectCoverage: boolean,
   ): SearchResult {
     const dependencyResolver = new DependencyResolver(
@@ -208,7 +220,7 @@ export default class SearchSource {
     };
   }
 
-  findTestsByPaths(paths: Array<Path>): SearchResult {
+  findTestsByPaths(paths: Array<Config.Path>): SearchResult {
     return {
       tests: toTests(
         this._context,
@@ -220,7 +232,7 @@ export default class SearchSource {
   }
 
   findRelatedTestsFromPattern(
-    paths: Array<Path>,
+    paths: Array<Config.Path>,
     collectCoverage: boolean,
   ): SearchResult {
     if (Array.isArray(paths) && paths.length) {
@@ -233,20 +245,22 @@ export default class SearchSource {
   }
 
   findTestRelatedToChangedFiles(
-    changedFilesInfo: ChangedFilesInfo,
+    changedFilesInfo: ChangedFiles,
     collectCoverage: boolean,
   ) {
     const {repos, changedFiles} = changedFilesInfo;
     // no SCM (git/hg/...) is found in any of the roots.
-    const noSCM = Object.keys(repos).every(scm => repos[scm].size === 0);
+    const noSCM = (Object.keys(repos) as Array<
+      keyof ChangedFiles['repos']
+    >).every(scm => repos[scm].size === 0);
     return noSCM
       ? {noSCM: true, tests: []}
       : this.findRelatedTests(changedFiles, collectCoverage);
   }
 
-  _getTestPaths(
-    globalConfig: GlobalConfig,
-    changedFiles: ?ChangedFilesInfo,
+  private _getTestPaths(
+    globalConfig: Config.GlobalConfig,
+    changedFiles?: ChangedFiles,
   ): SearchResult {
     const paths = globalConfig.nonFlagArgs;
 
@@ -274,8 +288,8 @@ export default class SearchSource {
   }
 
   async getTestPaths(
-    globalConfig: GlobalConfig,
-    changedFiles: ?ChangedFilesInfo,
+    globalConfig: Config.GlobalConfig,
+    changedFiles: ChangedFiles | undefined,
   ): Promise<SearchResult> {
     const searchResult = this._getTestPaths(globalConfig, changedFiles);
 
@@ -284,9 +298,10 @@ export default class SearchSource {
     if (filterPath && !globalConfig.skipFilter) {
       const tests = searchResult.tests;
 
-      // $FlowFixMe: dynamic require.
-      const filter: Array<FilterResult> = require(filterPath);
-      const filterResult = await filter(tests.map(test => test.path));
+      const filter = require(filterPath);
+      const filterResult: {filtered: Array<FilterResult>} = await filter(
+        tests.map(test => test.path),
+      );
 
       if (!Array.isArray(filterResult.filtered)) {
         throw new Error(
diff --git a/packages/jest-core/src/SnapshotInteractiveMode.js b/packages/jest-core/src/SnapshotInteractiveMode.ts
similarity index 85%
rename from packages/jest-core/src/SnapshotInteractiveMode.js
rename to packages/jest-core/src/SnapshotInteractiveMode.ts
index 07c2a5a8f478..ab09e39c6979 100644
--- a/packages/jest-core/src/SnapshotInteractiveMode.js
+++ b/packages/jest-core/src/SnapshotInteractiveMode.ts
@@ -4,14 +4,11 @@
  * This source code is licensed under the BSD-style license found in the
  * LICENSE file in the root directory of this source tree. An additional grant
  * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @flow
  */
 
-import type {AggregatedResult, AssertionLocation} from 'types/TestResult';
-
 import chalk from 'chalk';
 import ansiEscapes from 'ansi-escapes';
+import {TestResult} from '@jest/types';
 import {KEYS} from 'jest-watcher';
 
 import {pluralize, specialChars} from 'jest-util';
@@ -19,17 +16,17 @@ import {pluralize, specialChars} from 'jest-util';
 const {ARROW, CLEAR} = specialChars;
 
 export default class SnapshotInteractiveMode {
-  _pipe: stream$Writable | tty$WriteStream;
-  _isActive: boolean;
-  _updateTestRunnerConfig: (
-    assertion: ?AssertionLocation,
+  private _pipe: NodeJS.WritableStream;
+  private _isActive: boolean;
+  private _updateTestRunnerConfig!: (
+    assertion: TestResult.AssertionLocation | null,
     shouldUpdateSnapshot: boolean,
-  ) => *;
-  _testAssertions: Array<AssertionLocation>;
-  _countPaths: number;
-  _skippedNum: number;
+  ) => unknown;
+  private _testAssertions!: Array<TestResult.AssertionLocation>;
+  private _countPaths!: number;
+  private _skippedNum: number;
 
-  constructor(pipe: stream$Writable | tty$WriteStream) {
+  constructor(pipe: NodeJS.WritableStream) {
     this._pipe = pipe;
     this._isActive = false;
     this._skippedNum = 0;
@@ -43,12 +40,12 @@ export default class SnapshotInteractiveMode {
     return this._skippedNum;
   }
 
-  _clearTestSummary() {
+  private _clearTestSummary() {
     this._pipe.write(ansiEscapes.cursorUp(6));
     this._pipe.write(ansiEscapes.eraseDown);
   }
 
-  _drawUIProgress() {
+  private _drawUIProgress() {
     this._clearTestSummary();
     const numPass = this._countPaths - this._testAssertions.length;
     const numRemaining = this._countPaths - numPass - this._skippedNum;
@@ -90,7 +87,7 @@ export default class SnapshotInteractiveMode {
     this._pipe.write(messages.filter(Boolean).join('\n') + '\n');
   }
 
-  _drawUIDoneWithSkipped() {
+  private _drawUIDoneWithSkipped() {
     this._pipe.write(CLEAR);
     const numPass = this._countPaths - this._testAssertions.length;
 
@@ -123,7 +120,7 @@ export default class SnapshotInteractiveMode {
     this._pipe.write(messages.filter(Boolean).join('\n') + '\n');
   }
 
-  _drawUIDone() {
+  private _drawUIDone() {
     this._pipe.write(CLEAR);
     const numPass = this._countPaths - this._testAssertions.length;
 
@@ -147,7 +144,7 @@ export default class SnapshotInteractiveMode {
     this._pipe.write(messages.filter(Boolean).join('\n') + '\n');
   }
 
-  _drawUIOverlay() {
+  private _drawUIOverlay() {
     if (this._testAssertions.length === 0) {
       return this._drawUIDone();
     }
@@ -166,7 +163,7 @@ export default class SnapshotInteractiveMode {
         this._skippedNum += 1;
 
         // move skipped test to the end
-        this._testAssertions.push(this._testAssertions.shift());
+        this._testAssertions.push(this._testAssertions.shift()!);
         if (this._testAssertions.length - this._skippedNum > 0) {
           this._run(false);
         } else {
@@ -208,7 +205,7 @@ export default class SnapshotInteractiveMode {
     this._run(false);
   }
 
-  updateWithResults(results: AggregatedResult) {
+  updateWithResults(results: TestResult.AggregatedResult) {
     const hasSnapshotFailure = !!results.snapshot.failure;
     if (hasSnapshotFailure) {
       this._drawUIOverlay();
@@ -225,23 +222,23 @@ export default class SnapshotInteractiveMode {
     this._run(false);
   }
 
-  _run(shouldUpdateSnapshot: boolean) {
+  private _run(shouldUpdateSnapshot: boolean) {
     const testAssertion = this._testAssertions[0];
     this._updateTestRunnerConfig(testAssertion, shouldUpdateSnapshot);
   }
 
   run(
-    failedSnapshotTestAssertions: Array<AssertionLocation>,
+    failedSnapshotTestAssertions: Array<TestResult.AssertionLocation>,
     onConfigChange: (
-      assertion: ?AssertionLocation,
+      assertion: TestResult.AssertionLocation | null,
       shouldUpdateSnapshot: boolean,
-    ) => *,
+    ) => unknown,
   ) {
     if (!failedSnapshotTestAssertions.length) {
       return;
     }
 
-    this._testAssertions = [].concat(failedSnapshotTestAssertions);
+    this._testAssertions = [...failedSnapshotTestAssertions];
     this._countPaths = this._testAssertions.length;
     this._updateTestRunnerConfig = onConfigChange;
     this._isActive = true;
diff --git a/packages/jest-core/src/TestNamePatternPrompt.js b/packages/jest-core/src/TestNamePatternPrompt.ts
similarity index 72%
rename from packages/jest-core/src/TestNamePatternPrompt.js
rename to packages/jest-core/src/TestNamePatternPrompt.ts
index bf728f272fa8..fe55aa6caf01 100644
--- a/packages/jest-core/src/TestNamePatternPrompt.js
+++ b/packages/jest-core/src/TestNamePatternPrompt.ts
@@ -3,24 +3,22 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {TestResult} from 'types/TestResult';
-import type {ScrollOptions} from 'types/Watch';
-
 import {
   PatternPrompt,
   Prompt,
+  ScrollOptions,
   printPatternCaret,
   printRestoredPatternCaret,
 } from 'jest-watcher';
+import {TestResult} from '@jest/types';
 
+// TODO: Make underscored props `private`
 export default class TestNamePatternPrompt extends PatternPrompt {
-  _cachedTestResults: Array<TestResult>;
+  _cachedTestResults: Array<TestResult.TestResult>;
 
-  constructor(pipe: stream$Writable | tty$WriteStream, prompt: Prompt) {
+  constructor(pipe: NodeJS.WritableStream, prompt: Prompt) {
     super(pipe, prompt);
     this._entityName = 'tests';
     this._cachedTestResults = [];
@@ -28,17 +26,17 @@ export default class TestNamePatternPrompt extends PatternPrompt {
 
   _onChange(pattern: string, options: ScrollOptions) {
     super._onChange(pattern, options);
-    this._printPrompt(pattern, options);
+    this._printPrompt(pattern);
   }
 
-  _printPrompt(pattern: string, options: ScrollOptions) {
+  _printPrompt(pattern: string) {
     const pipe = this._pipe;
     printPatternCaret(pattern, pipe);
     printRestoredPatternCaret(pattern, this._currentUsageRows, pipe);
   }
 
   _getMatchedTests(pattern: string) {
-    let regex;
+    let regex: RegExp;
 
     try {
       regex = new RegExp(pattern, 'i');
@@ -46,7 +44,7 @@ export default class TestNamePatternPrompt extends PatternPrompt {
       return [];
     }
 
-    const matchedTests = [];
+    const matchedTests: Array<string> = [];
 
     this._cachedTestResults.forEach(({testResults}) =>
       testResults.forEach(({title}) => {
@@ -59,7 +57,7 @@ export default class TestNamePatternPrompt extends PatternPrompt {
     return matchedTests;
   }
 
-  updateCachedTestResults(testResults: Array<TestResult> = []) {
+  updateCachedTestResults(testResults: Array<TestResult.TestResult> = []) {
     this._cachedTestResults = testResults;
   }
 }
diff --git a/packages/jest-core/src/TestPathPatternPrompt.js b/packages/jest-core/src/TestPathPatternPrompt.ts
similarity index 64%
rename from packages/jest-core/src/TestPathPatternPrompt.js
rename to packages/jest-core/src/TestPathPatternPrompt.ts
index 330be132fdbe..47922c4e91c5 100644
--- a/packages/jest-core/src/TestPathPatternPrompt.js
+++ b/packages/jest-core/src/TestPathPatternPrompt.ts
@@ -3,41 +3,40 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {Context} from 'types/Context';
-import type {Test} from 'types/TestRunner';
-import type {ScrollOptions} from 'types/Watch';
-import type SearchSource from './SearchSource';
+import {Context} from 'jest-runtime';
+import {Test} from 'jest-runner';
 
 import {
   PatternPrompt,
   Prompt,
+  ScrollOptions,
   printPatternCaret,
   printRestoredPatternCaret,
 } from 'jest-watcher';
+import SearchSource from './SearchSource';
 
-type SearchSources = Array<{|
-  context: Context,
-  searchSource: SearchSource,
-|}>;
+type SearchSources = Array<{
+  context: Context;
+  searchSource: SearchSource;
+}>;
 
+// TODO: Make underscored props `private`
 export default class TestPathPatternPrompt extends PatternPrompt {
-  _searchSources: SearchSources;
+  _searchSources?: SearchSources;
 
-  constructor(pipe: stream$Writable | tty$WriteStream, prompt: Prompt) {
+  constructor(pipe: NodeJS.WritableStream, prompt: Prompt) {
     super(pipe, prompt);
     this._entityName = 'filenames';
   }
 
   _onChange(pattern: string, options: ScrollOptions) {
     super._onChange(pattern, options);
-    this._printPrompt(pattern, options);
+    this._printPrompt(pattern);
   }
 
-  _printPrompt(pattern: string, options: ScrollOptions) {
+  _printPrompt(pattern: string) {
     const pipe = this._pipe;
     printPatternCaret(pattern, pipe);
     printRestoredPatternCaret(pattern, this._currentUsageRows, pipe);
@@ -50,9 +49,9 @@ export default class TestPathPatternPrompt extends PatternPrompt {
       regex = new RegExp(pattern, 'i');
     } catch (e) {}
 
-    let tests = [];
-    if (regex) {
-      this._searchSources.forEach(({searchSource, context}) => {
+    let tests: Array<Test> = [];
+    if (regex && this._searchSources) {
+      this._searchSources.forEach(({searchSource}) => {
         tests = tests.concat(searchSource.findMatchingTests(pattern).tests);
       });
     }
diff --git a/packages/jest-core/src/TestScheduler.js b/packages/jest-core/src/TestScheduler.ts
similarity index 84%
rename from packages/jest-core/src/TestScheduler.js
rename to packages/jest-core/src/TestScheduler.ts
index 3427f60aa576..737241fd4d4b 100644
--- a/packages/jest-core/src/TestScheduler.js
+++ b/packages/jest-core/src/TestScheduler.ts
@@ -3,56 +3,53 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {AggregatedResult, TestResult} from 'types/TestResult';
-import type {GlobalConfig, ReporterConfig, Path} from 'types/Config';
-import type {Context} from 'types/Context';
-import type {Reporter, Test} from 'types/TestRunner';
-
 import chalk from 'chalk';
 import {formatExecError} from 'jest-message-util';
-import {
-  addResult,
-  buildFailureTestResult,
-  makeEmptyAggregatedTestResult,
-} from './testResultHelpers';
+import {Config, TestResult} from '@jest/types';
+import snapshot from 'jest-snapshot';
+import TestRunner, {Test} from 'jest-runner';
+import {Context} from 'jest-runtime';
 import {
   CoverageReporter,
   DefaultReporter,
   NotifyReporter,
   SummaryReporter,
   VerboseReporter,
+  // @ts-ignore: Not migrated to TS
 } from '@jest/reporters';
 import exit from 'exit';
+import {
+  addResult,
+  buildFailureTestResult,
+  makeEmptyAggregatedTestResult,
+} from './testResultHelpers';
 import ReporterDispatcher from './ReporterDispatcher';
-import snapshot from 'jest-snapshot';
-import TestRunner from 'jest-runner';
 import TestWatcher from './TestWatcher';
 import {shouldRunInBand} from './testSchedulerHelper';
+import {Reporter} from './types';
 
 // The default jest-runner is required because it is the default test runner
 // and required implicitly through the `runner` ProjectConfig option.
 TestRunner;
 
-export type TestSchedulerOptions = {|
-  startRun: (globalConfig: GlobalConfig) => *,
-|};
-export type TestSchedulerContext = {|
-  firstRun: boolean,
-  previousSuccess: boolean,
-  changedFiles?: Set<Path>,
-|};
+export type TestSchedulerOptions = {
+  startRun: (globalConfig: Config.GlobalConfig) => void;
+};
+export type TestSchedulerContext = {
+  firstRun: boolean;
+  previousSuccess: boolean;
+  changedFiles?: Set<Config.Path>;
+};
 export default class TestScheduler {
-  _dispatcher: ReporterDispatcher;
-  _globalConfig: GlobalConfig;
-  _options: TestSchedulerOptions;
-  _context: TestSchedulerContext;
+  private _dispatcher: ReporterDispatcher;
+  private _globalConfig: Config.GlobalConfig;
+  private _options: TestSchedulerOptions;
+  private _context: TestSchedulerContext;
 
   constructor(
-    globalConfig: GlobalConfig,
+    globalConfig: Config.GlobalConfig,
     options: TestSchedulerOptions,
     context: TestSchedulerContext,
   ) {
@@ -73,7 +70,7 @@ export default class TestScheduler {
 
   async scheduleTests(tests: Array<Test>, watcher: TestWatcher) {
     const onStart = this._dispatcher.onTestStart.bind(this._dispatcher);
-    const timings = [];
+    const timings: Array<number> = [];
     const contexts = new Set();
     tests.forEach(test => {
       contexts.add(test.context);
@@ -94,7 +91,7 @@ export default class TestScheduler {
       timings,
     );
 
-    const onResult = async (test: Test, testResult: TestResult) => {
+    const onResult = async (test: Test, testResult: TestResult.TestResult) => {
       if (watcher.isInterrupted()) {
         return Promise.resolve();
       }
@@ -130,7 +127,10 @@ export default class TestScheduler {
       return this._bailIfNeeded(contexts, aggregatedResults, watcher);
     };
 
-    const onFailure = async (test, error) => {
+    const onFailure = async (
+      test: Test,
+      error: TestResult.SerializableError,
+    ) => {
       if (watcher.isInterrupted()) {
         return;
       }
@@ -173,11 +173,10 @@ export default class TestScheduler {
     const testRunners = Object.create(null);
     contexts.forEach(({config}) => {
       if (!testRunners[config.runner]) {
-        // $FlowFixMe
-        testRunners[config.runner] = new (require(config.runner): TestRunner)(
-          this._globalConfig,
-          {changedFiles: this._context && this._context.changedFiles},
-        );
+        const Runner: typeof TestRunner = require(config.runner);
+        testRunners[config.runner] = new Runner(this._globalConfig, {
+          changedFiles: this._context && this._context.changedFiles,
+        });
       }
     });
 
@@ -223,8 +222,8 @@ export default class TestScheduler {
     return aggregatedResults;
   }
 
-  _partitionTests(
-    testRunners: {[key: string]: TestRunner, __proto__: null},
+  private _partitionTests(
+    testRunners: {[key: string]: TestRunner},
     tests: Array<Test>,
   ) {
     if (Object.keys(testRunners).length > 1) {
@@ -246,8 +245,8 @@ export default class TestScheduler {
     }
   }
 
-  _shouldAddDefaultReporters(
-    reporters?: Array<string | ReporterConfig>,
+  private _shouldAddDefaultReporters(
+    reporters?: Array<string | Config.ReporterConfig>,
   ): boolean {
     return (
       !reporters ||
@@ -257,7 +256,7 @@ export default class TestScheduler {
     );
   }
 
-  _setupReporters() {
+  private _setupReporters() {
     const {collectCoverage, notify, reporters} = this._globalConfig;
     const isDefault = this._shouldAddDefaultReporters(reporters);
 
@@ -288,7 +287,7 @@ export default class TestScheduler {
     }
   }
 
-  _setupDefaultReporters(collectCoverage: boolean) {
+  private _setupDefaultReporters(collectCoverage: boolean) {
     this.addReporter(
       this._globalConfig.verbose
         ? new VerboseReporter(this._globalConfig)
@@ -306,14 +305,15 @@ export default class TestScheduler {
     this.addReporter(new SummaryReporter(this._globalConfig));
   }
 
-  _addCustomReporters(reporters: Array<string | ReporterConfig>) {
-    reporters.forEach((reporter, index) => {
+  private _addCustomReporters(
+    reporters: Array<string | Config.ReporterConfig>,
+  ) {
+    reporters.forEach(reporter => {
       const {options, path} = this._getReporterProps(reporter);
 
       if (path === 'default') return;
 
       try {
-        // $FlowFixMe
         const Reporter = require(path);
         this.addReporter(new Reporter(this._globalConfig, options));
       } catch (error) {
@@ -331,9 +331,9 @@ export default class TestScheduler {
    * Get properties of a reporter in an object
    * to make dealing with them less painful.
    */
-  _getReporterProps(
-    reporter: string | ReporterConfig,
-  ): {path: string, options?: Object} {
+  private _getReporterProps(
+    reporter: string | Config.ReporterConfig,
+  ): {path: string; options: {[key: string]: unknown}} {
     if (typeof reporter === 'string') {
       return {options: this._options, path: reporter};
     } else if (Array.isArray(reporter)) {
@@ -344,9 +344,9 @@ export default class TestScheduler {
     throw new Error('Reporter should be either a string or an array');
   }
 
-  _bailIfNeeded(
+  private _bailIfNeeded(
     contexts: Set<Context>,
-    aggregatedResults: AggregatedResult,
+    aggregatedResults: TestResult.AggregatedResult,
     watcher: TestWatcher,
   ): Promise<void> {
     if (
@@ -376,7 +376,7 @@ const createAggregatedResults = (numTotalTestSuites: number) => {
   return result;
 };
 
-const getEstimatedTime = (timings, workers) => {
+const getEstimatedTime = (timings: Array<number>, workers: number) => {
   if (!timings.length) {
     return 0;
   }
diff --git a/packages/jest-core/src/TestSequencer.js b/packages/jest-core/src/TestSequencer.ts
similarity index 85%
rename from packages/jest-core/src/TestSequencer.js
rename to packages/jest-core/src/TestSequencer.ts
index 0fab2560639c..3928d695fb9d 100644
--- a/packages/jest-core/src/TestSequencer.js
+++ b/packages/jest-core/src/TestSequencer.ts
@@ -3,26 +3,23 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {AggregatedResult} from 'types/TestResult';
-import type {Context} from 'types/Context';
-import type {Test} from 'types/TestRunner';
-
 import fs from 'fs';
+import {TestResult} from '@jest/types';
 import {getCacheFilePath} from 'jest-haste-map';
+import {Context} from 'jest-runtime';
+import {Test} from 'jest-runner';
 
 const FAIL = 0;
 const SUCCESS = 1;
 
 type Cache = {
-  [key: string]: [0 | 1, number],
+  [key: string]: [0 | 1, number];
 };
 
 export default class TestSequencer {
-  _cache: Map<Context, Cache>;
+  private _cache: Map<Context, Cache>;
 
   constructor() {
     this._cache = new Map();
@@ -65,12 +62,13 @@ export default class TestSequencer {
   // subsequent runs we use that to run the slowest tests first, yielding the
   // fastest results.
   sort(tests: Array<Test>): Array<Test> {
-    const stats = {};
-    const fileSize = ({path, context: {hasteFS}}) =>
+    const stats: {[path: string]: number} = {};
+    const fileSize = ({path, context: {hasteFS}}: Test) =>
       stats[path] || (stats[path] = hasteFS.getSize(path) || 0);
-    const hasFailed = (cache, test) =>
+    const hasFailed = (cache: Cache, test: Test) =>
       cache[test.path] && cache[test.path][0] === FAIL;
-    const time = (cache, test) => cache[test.path] && cache[test.path][1];
+    const time = (cache: Cache, test: Test) =>
+      cache[test.path] && cache[test.path][1];
 
     tests.forEach(test => (test.duration = time(this._getCache(test), test)));
     return tests.sort((testA, testB) => {
@@ -92,7 +90,7 @@ export default class TestSequencer {
     });
   }
 
-  cacheResults(tests: Array<Test>, results: AggregatedResult) {
+  cacheResults(tests: Array<Test>, results: TestResult.AggregatedResult) {
     const map = Object.create(null);
     tests.forEach(test => (map[test.path] = test));
     results.testResults.forEach(testResult => {
diff --git a/packages/jest-core/src/TestWatcher.js b/packages/jest-core/src/TestWatcher.ts
similarity index 84%
rename from packages/jest-core/src/TestWatcher.js
rename to packages/jest-core/src/TestWatcher.ts
index 9a126b258489..fce64763633a 100644
--- a/packages/jest-core/src/TestWatcher.js
+++ b/packages/jest-core/src/TestWatcher.ts
@@ -3,19 +3,17 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import EventEmitter from 'events';
+import {EventEmitter} from 'events';
 
-type State = {|
-  interrupted: boolean,
-|};
+type State = {
+  interrupted: boolean;
+};
 
 export default class TestWatcher extends EventEmitter {
   state: State;
-  _isWatchMode: boolean;
+  private _isWatchMode: boolean;
 
   constructor({isWatchMode}: {isWatchMode: boolean}) {
     super();
diff --git a/packages/jest-core/src/__tests__/SearchSource.test.js b/packages/jest-core/src/__tests__/SearchSource.test.ts
similarity index 87%
rename from packages/jest-core/src/__tests__/SearchSource.test.js
rename to packages/jest-core/src/__tests__/SearchSource.test.ts
index d3ed9b7117a0..8f9418274a1f 100644
--- a/packages/jest-core/src/__tests__/SearchSource.test.js
+++ b/packages/jest-core/src/__tests__/SearchSource.test.ts
@@ -6,9 +6,12 @@
  *
  */
 
-'use strict';
-
 import path from 'path';
+import Runtime from 'jest-runtime';
+import {normalize} from 'jest-config';
+import {Test} from 'jest-runner';
+import {Config} from '@jest/types';
+import SearchSource, {SearchResult} from '../SearchSource';
 
 jest.setTimeout(15000);
 
@@ -17,22 +20,13 @@ const testRegex = path.sep + '__testtests__' + path.sep;
 const testMatch = ['**/__testtests__/**/*'];
 const maxWorkers = 1;
 
-const toPaths = tests => tests.map(({path}) => path);
+const toPaths = (tests: Array<Test>) => tests.map(({path}) => path);
 
-let findMatchingTests;
-let normalize;
+let findMatchingTests: (config: Config.ProjectConfig) => Promise<SearchResult>;
 
 describe('SearchSource', () => {
   const name = 'SearchSource';
-  let Runtime;
-  let SearchSource;
-  let searchSource;
-
-  beforeEach(() => {
-    Runtime = require('jest-runtime');
-    SearchSource = require('../SearchSource').default;
-    normalize = require('jest-config').normalize;
-  });
+  let searchSource: SearchSource;
 
   describe('isTestFilePath', () => {
     let config;
@@ -44,11 +38,13 @@ describe('SearchSource', () => {
           rootDir: '.',
           roots: [],
         },
-        {},
+        {} as Config.Argv,
       ).options;
-      return Runtime.createContext(config, {maxWorkers}).then(context => {
-        searchSource = new SearchSource(context);
-      });
+      return Runtime.createContext(config, {maxWorkers, watchman: false}).then(
+        context => {
+          searchSource = new SearchSource(context);
+        },
+      );
     });
 
     // micromatch doesn't support '..' through the globstar ('**') to avoid
@@ -60,13 +56,14 @@ describe('SearchSource', () => {
             name,
             rootDir: '.',
             roots: [],
-            testMatch: null,
+            testMatch: undefined,
             testRegex: '(/__tests__/.*|(\\.|/)(test|spec))\\.jsx?$',
           },
-          {},
+          {} as Config.Argv,
         ).options;
         return Runtime.createContext(config, {
           maxWorkers,
+          watchman: false,
         }).then(context => {
           searchSource = new SearchSource(context);
 
@@ -95,9 +92,10 @@ describe('SearchSource', () => {
 
   describe('testPathsMatching', () => {
     beforeEach(() => {
-      findMatchingTests = config =>
+      findMatchingTests = (config: Config.ProjectConfig) =>
         Runtime.createContext(config, {
           maxWorkers,
+          watchman: false,
         }).then(context => new SearchSource(context).findMatchingTests());
     });
 
@@ -107,10 +105,10 @@ describe('SearchSource', () => {
           moduleFileExtensions: ['js', 'jsx', 'txt'],
           name,
           rootDir,
-          testMatch: null,
+          testMatch: undefined,
           testRegex: 'not-really-a-test',
         },
-        {},
+        {} as Config.Argv,
       );
       return findMatchingTests(config).then(data => {
         const relPaths = toPaths(data.tests)
@@ -134,7 +132,7 @@ describe('SearchSource', () => {
           testMatch: ['**/not-really-a-test.txt', '!**/do-not-match-me.txt'],
           testRegex: '',
         },
-        {},
+        {} as Config.Argv,
       );
       return findMatchingTests(config).then(data => {
         const relPaths = toPaths(data.tests)
@@ -155,10 +153,10 @@ describe('SearchSource', () => {
           moduleFileExtensions: ['js', 'jsx'],
           name,
           rootDir,
-          testMatch: null,
+          testMatch: undefined,
           testRegex: 'test.jsx?',
         },
-        {},
+        {} as Config.Argv,
       );
       return findMatchingTests(config).then(data => {
         const relPaths = toPaths(data.tests).map(absPath =>
@@ -180,7 +178,7 @@ describe('SearchSource', () => {
           testMatch: ['**/test.js?(x)'],
           testRegex: '',
         },
-        {},
+        {} as Config.Argv,
       );
       return findMatchingTests(config).then(data => {
         const relPaths = toPaths(data.tests).map(absPath =>
@@ -198,10 +196,10 @@ describe('SearchSource', () => {
         {
           name,
           rootDir,
-          testMatch: null,
+          testMatch: undefined,
           testRegex,
         },
-        {},
+        {} as Config.Argv,
       );
       return findMatchingTests(config).then(data => {
         const relPaths = toPaths(data.tests).map(absPath =>
@@ -222,7 +220,7 @@ describe('SearchSource', () => {
           testMatch,
           testRegex: '',
         },
-        {},
+        {} as Config.Argv,
       );
       return findMatchingTests(config).then(data => {
         const relPaths = toPaths(data.tests).map(absPath =>
@@ -241,9 +239,9 @@ describe('SearchSource', () => {
           name,
           rootDir: path.resolve(__dirname, 'test_root_with_(parentheses)'),
           testMatch: ['<rootDir>**/__testtests__/**/*'],
-          testRegex: null,
+          testRegex: undefined,
         },
-        {},
+        {} as Config.Argv,
       );
       return findMatchingTests(config).then(data => {
         const relPaths = toPaths(data.tests).map(absPath =>
@@ -263,7 +261,7 @@ describe('SearchSource', () => {
           rootDir,
           testMatch,
         },
-        {},
+        {} as Config.Argv,
       );
       return findMatchingTests(config).then(data => {
         const relPaths = toPaths(data.tests).map(absPath =>
@@ -284,7 +282,7 @@ describe('SearchSource', () => {
           rootDir,
           testMatch,
         },
-        {},
+        {} as Config.Argv,
       );
       return findMatchingTests(config).then(data => {
         const relPaths = toPaths(data.tests).map(absPath =>
@@ -305,7 +303,7 @@ describe('SearchSource', () => {
           rootDir,
           testMatch,
         },
-        {},
+        {} as Config.Argv,
       );
       return findMatchingTests(config).then(data => {
         const relPaths = toPaths(data.tests).map(absPath =>
@@ -323,10 +321,10 @@ describe('SearchSource', () => {
         {
           name,
           rootDir,
-          testMatch: null,
+          testMatch: undefined,
           testRegex,
         },
-        {},
+        {} as Config.Argv,
       );
       return findMatchingTests(config).then(data => {
         const relPaths = toPaths(data.tests).map(absPath =>
@@ -347,7 +345,7 @@ describe('SearchSource', () => {
           testMatch,
           testRegex: '',
         },
-        {},
+        {} as Config.Argv,
       );
       return findMatchingTests(config).then(data => {
         const relPaths = toPaths(data.tests).map(absPath =>
@@ -388,20 +386,23 @@ describe('SearchSource', () => {
               '__tests__',
               'haste_impl.js',
             ),
+            providesModuleNodeModules: [],
           },
           name: 'SearchSource-findRelatedTests-tests',
           rootDir,
         },
-        {},
+        {} as Config.Argv,
+      );
+      Runtime.createContext(config, {maxWorkers, watchman: false}).then(
+        context => {
+          searchSource = new SearchSource(context);
+          done();
+        },
       );
-      Runtime.createContext(config, {maxWorkers}).then(context => {
-        searchSource = new SearchSource(context);
-        done();
-      });
     });
 
     it('makes sure a file is related to itself', () => {
-      const data = searchSource.findRelatedTests(new Set([rootPath]));
+      const data = searchSource.findRelatedTests(new Set([rootPath]), false);
       expect(toPaths(data.tests)).toEqual([rootPath]);
     });
 
@@ -410,7 +411,7 @@ describe('SearchSource', () => {
       const file2Path = path.join(rootDir, 'RequireRegularModule.js');
       const loggingDep = path.join(rootDir, 'logging.js');
       const parentDep = path.join(rootDir, 'ModuleWithSideEffects.js');
-      const data = searchSource.findRelatedTests(new Set([filePath]));
+      const data = searchSource.findRelatedTests(new Set([filePath]), false);
       expect(toPaths(data.tests).sort()).toEqual([
         parentDep,
         filePath,
@@ -429,7 +430,7 @@ describe('SearchSource', () => {
         new Set([regular, requireRegular, unrelatedFile]),
         true,
       );
-      expect(Array.from(data.collectCoverageFrom)).toEqual([
+      expect(Array.from(data.collectCoverageFrom || [])).toEqual([
         'RegularModule.js',
       ]);
     });
@@ -444,35 +445,37 @@ describe('SearchSource', () => {
           rootDir,
           testMatch,
         },
-        {},
+        {} as Config.Argv,
+      );
+      Runtime.createContext(config, {maxWorkers, watchman: false}).then(
+        context => {
+          searchSource = new SearchSource(context);
+          done();
+        },
       );
-      Runtime.createContext(config, {maxWorkers}).then(context => {
-        searchSource = new SearchSource(context);
-        done();
-      });
     });
 
     it('returns empty search result for empty input', () => {
-      const input = [];
-      const data = searchSource.findRelatedTestsFromPattern(input);
+      const input: Array<Config.Path> = [];
+      const data = searchSource.findRelatedTestsFromPattern(input, false);
       expect(data.tests).toEqual([]);
     });
 
     it('returns empty search result for invalid input', () => {
       const input = ['non-existend.js'];
-      const data = searchSource.findRelatedTestsFromPattern(input);
+      const data = searchSource.findRelatedTestsFromPattern(input, false);
       expect(data.tests).toEqual([]);
     });
 
     it('returns empty search result if no related tests were found', () => {
       const input = ['no_tests.js'];
-      const data = searchSource.findRelatedTestsFromPattern(input);
+      const data = searchSource.findRelatedTestsFromPattern(input, false);
       expect(data.tests).toEqual([]);
     });
 
     it('finds tests for a single file', () => {
       const input = ['packages/jest-core/src/__tests__/test_root/module.jsx'];
-      const data = searchSource.findRelatedTestsFromPattern(input);
+      const data = searchSource.findRelatedTestsFromPattern(input, false);
       expect(toPaths(data.tests).sort()).toEqual([
         path.join(rootDir, '__testtests__', 'test.js'),
         path.join(rootDir, '__testtests__', 'test.jsx'),
@@ -484,7 +487,7 @@ describe('SearchSource', () => {
         'packages/jest-core/src/__tests__/test_root/module.jsx',
         'packages/jest-core/src/__tests__/test_root/module.foobar',
       ];
-      const data = searchSource.findRelatedTestsFromPattern(input);
+      const data = searchSource.findRelatedTestsFromPattern(input, false);
       expect(toPaths(data.tests).sort()).toEqual([
         path.join(rootDir, '__testtests__', 'test.foobar'),
         path.join(rootDir, '__testtests__', 'test.js'),
@@ -500,11 +503,11 @@ describe('SearchSource', () => {
             rootDir: '.',
             roots: ['/foo/bar/prefix'],
           },
-          {},
+          {} as Config.Argv,
         ).options;
 
         searchSource = new SearchSource(
-          await Runtime.createContext(config, {maxWorkers}),
+          await Runtime.createContext(config, {maxWorkers, watchman: false}),
         );
 
         const input = ['/foo/bar/prefix-suffix/__tests__/my-test.test.js'];
diff --git a/packages/jest-core/src/__tests__/globals.test.js b/packages/jest-core/src/__tests__/globals.test.ts
similarity index 97%
rename from packages/jest-core/src/__tests__/globals.test.js
rename to packages/jest-core/src/__tests__/globals.test.ts
index 15e89bfceafa..7c6b2ca5354d 100644
--- a/packages/jest-core/src/__tests__/globals.test.js
+++ b/packages/jest-core/src/__tests__/globals.test.ts
@@ -3,9 +3,8 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
+
 'use strict';
 
 describe('Common globals', () => {
diff --git a/packages/jest-core/src/cli/index.js b/packages/jest-core/src/cli/index.ts
similarity index 79%
rename from packages/jest-core/src/cli/index.js
rename to packages/jest-core/src/cli/index.ts
index b71054c167de..a3837305829b 100644
--- a/packages/jest-core/src/cli/index.js
+++ b/packages/jest-core/src/cli/index.ts
@@ -3,41 +3,43 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {AggregatedResult} from 'types/TestResult';
-import type {Argv} from 'types/Argv';
-import type {GlobalConfig, Path} from 'types/Config';
-
+import {Config, TestResult} from '@jest/types';
 import {Console, createDirectory, preRunMessage} from 'jest-util';
 import {readConfigs} from 'jest-config';
+import Runtime, {Context} from 'jest-runtime';
+import {ChangedFilesPromise} from 'jest-changed-files';
+import HasteMap from 'jest-haste-map';
 import chalk from 'chalk';
-import createContext from '../lib/create_context';
+import rimraf from 'rimraf';
 import exit from 'exit';
+import createContext from '../lib/create_context';
 import getChangedFilesPromise from '../getChangedFilesPromise';
 import {formatHandleErrors} from '../collectHandles';
 import handleDeprecationWarnings from '../lib/handle_deprecation_warnings';
 import runJest from '../runJest';
-import Runtime from 'jest-runtime';
 import TestWatcher from '../TestWatcher';
 import watch from '../watch';
 import pluralize from '../pluralize';
-import rimraf from 'rimraf';
 import logDebugMessages from '../lib/log_debug_messages';
 
 const {print: preRunMessagePrint} = preRunMessage;
 
+type OnCompleteCallback = (results: TestResult.AggregatedResult) => void;
+
 export const runCLI = async (
-  argv: Argv,
-  projects: Array<Path>,
-): Promise<{results: AggregatedResult, globalConfig: GlobalConfig}> => {
+  argv: Config.Argv,
+  projects: Array<Config.Path>,
+): Promise<{
+  results: TestResult.AggregatedResult;
+  globalConfig: Config.GlobalConfig;
+}> => {
   const realFs = require('fs');
   const fs = require('graceful-fs');
   fs.gracefulify(realFs);
 
-  let results;
+  let results: TestResult.AggregatedResult | undefined;
 
   // If we output a JSON object, we can't write anything to stdout, since
   // it'll break the JSON structure and it won't be valid.
@@ -72,7 +74,7 @@ export const runCLI = async (
     configs,
     hasDeprecationWarnings,
     outputStream,
-    (r: AggregatedResult) => (results = r),
+    r => (results = r),
   );
 
   if (argv.watch || argv.watchAll) {
@@ -107,9 +109,9 @@ export const runCLI = async (
 };
 
 const buildContextsAndHasteMaps = async (
-  configs,
-  globalConfig,
-  outputStream,
+  configs: Array<Config.ProjectConfig>,
+  globalConfig: Config.GlobalConfig,
+  outputStream: NodeJS.WritableStream,
 ) => {
   const hasteMapInstances = Array(configs.length);
   const contexts = await Promise.all(
@@ -131,11 +133,11 @@ const buildContextsAndHasteMaps = async (
 };
 
 const _run = async (
-  globalConfig,
-  configs,
-  hasDeprecationWarnings,
-  outputStream,
-  onComplete,
+  globalConfig: Config.GlobalConfig,
+  configs: Array<Config.ProjectConfig>,
+  hasDeprecationWarnings: boolean,
+  outputStream: NodeJS.WriteStream,
+  onComplete: OnCompleteCallback,
 ) => {
   // Queries to hg/git can take a while, so we need to start the process
   // as soon as possible, so by the time we need the result it's already there.
@@ -166,12 +168,12 @@ const _run = async (
 };
 
 const runWatch = async (
-  contexts,
-  configs,
-  hasDeprecationWarnings,
-  globalConfig,
-  outputStream,
-  hasteMapInstances,
+  contexts: Array<Context>,
+  _configs: Array<Config.ProjectConfig>,
+  hasDeprecationWarnings: boolean,
+  globalConfig: Config.GlobalConfig,
+  outputStream: NodeJS.WriteStream,
+  hasteMapInstances: Array<HasteMap>,
 ) => {
   if (hasDeprecationWarnings) {
     try {
@@ -186,20 +188,20 @@ const runWatch = async (
 };
 
 const runWithoutWatch = async (
-  globalConfig,
-  contexts,
-  outputStream,
-  onComplete,
-  changedFilesPromise,
+  globalConfig: Config.GlobalConfig,
+  contexts: Array<Context>,
+  outputStream: NodeJS.WritableStream,
+  onComplete: OnCompleteCallback,
+  changedFilesPromise?: ChangedFilesPromise,
 ) => {
-  const startRun = async () => {
+  const startRun = async (): Promise<void | null> => {
     if (!globalConfig.listTests) {
       preRunMessagePrint(outputStream);
     }
     return runJest({
       changedFilesPromise,
       contexts,
-      failedTestsCache: null,
+      failedTestsCache: undefined,
       globalConfig,
       onComplete,
       outputStream,
diff --git a/packages/jest-core/src/collectHandles.js b/packages/jest-core/src/collectHandles.ts
similarity index 79%
rename from packages/jest-core/src/collectHandles.js
rename to packages/jest-core/src/collectHandles.ts
index fcc1f4368ec7..b7653056a6ae 100644
--- a/packages/jest-core/src/collectHandles.js
+++ b/packages/jest-core/src/collectHandles.ts
@@ -3,17 +3,16 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {ProjectConfig} from 'types/Config';
-
+import {Config} from '@jest/types';
 import {formatExecError} from 'jest-message-util';
 import {ErrorWithStack} from 'jest-util';
 import stripAnsi from 'strip-ansi';
 
-function stackIsFromUser(stack) {
+type AsyncHook = import('async_hooks').AsyncHook;
+
+function stackIsFromUser(stack: string) {
   // Either the test file, or something required by it
   if (stack.includes('Runtime.requireModule')) {
     return true;
@@ -38,29 +37,26 @@ function stackIsFromUser(stack) {
 // Inspired by https://github.com/mafintosh/why-is-node-running/blob/master/index.js
 // Extracted as we want to format the result ourselves
 export default function collectHandles(): () => Array<Error> {
-  const activeHandles: Map<string, Error> = new Map();
-
-  function initHook(asyncId, type) {
-    if (type === 'PROMISE' || type === 'TIMERWRAP') {
-      return;
-    }
-    const error = new ErrorWithStack(type, initHook);
-
-    if (stackIsFromUser(error.stack)) {
-      activeHandles.set(asyncId, error);
-    }
-  }
+  const activeHandles: Map<number, Error> = new Map();
 
-  let hook;
+  let hook: AsyncHook;
 
   try {
-    // $FlowFixMe: Node core module
-    const asyncHooks = require('async_hooks');
+    const asyncHooks: typeof import('async_hooks') = require('async_hooks');
     hook = asyncHooks.createHook({
       destroy(asyncId) {
         activeHandles.delete(asyncId);
       },
-      init: initHook,
+      init: function initHook(asyncId, type) {
+        if (type === 'PROMISE' || type === 'TIMERWRAP') {
+          return;
+        }
+        const error = new ErrorWithStack(type, initHook);
+
+        if (stackIsFromUser(error.stack || '')) {
+          activeHandles.set(asyncId, error);
+        }
+      },
     });
 
     hook.enable();
@@ -86,7 +82,7 @@ export default function collectHandles(): () => Array<Error> {
 
 export function formatHandleErrors(
   errors: Array<Error>,
-  config: ProjectConfig,
+  config: Config.ProjectConfig,
 ): Array<string> {
   const stacks = new Set();
 
diff --git a/packages/jest-core/src/coverage.template b/packages/jest-core/src/coverage.template
deleted file mode 100644
index d20d08eb88a1..000000000000
--- a/packages/jest-core/src/coverage.template
+++ /dev/null
@@ -1,29 +0,0 @@
-// Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
-
-// Instrumentation Header
-{
-    var <%= instrumented.names.statement %>;
-    var <%= instrumented.names.expression %>;
-    var <%= instrumented.names.block %>;
-    var nodes = <%= coverageStorageVar %>.nodes = {};
-    var blocks = <%= coverageStorageVar %>.blocks = {};
-
-    <%= instrumented.names.statement %> = function(i) {
-        var node = nodes[i] = (nodes[i] || {index: i, count:0})
-        node.count++;
-    };
-
-    <%= instrumented.names.expression %> = function(i) {
-        var node = nodes[i] = (nodes[i] || {index: i, count:0})
-        node.count++;
-    };
-
-    <%= instrumented.names.block %> = function(i) {
-        var block = blocks[i] = (blocks[i] || {index: i, count:0})
-        block.count++;
-    };
-};
-////////////////////////
-
-// Instrumented Code
-<%= source %>
diff --git a/packages/jest-core/src/getChangedFilesPromise.js b/packages/jest-core/src/getChangedFilesPromise.ts
similarity index 70%
rename from packages/jest-core/src/getChangedFilesPromise.js
rename to packages/jest-core/src/getChangedFilesPromise.ts
index f7f0d4df4e0c..eec8f482836f 100644
--- a/packages/jest-core/src/getChangedFilesPromise.js
+++ b/packages/jest-core/src/getChangedFilesPromise.ts
@@ -3,23 +3,20 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {GlobalConfig, ProjectConfig} from 'types/Config';
-import type {ChangedFilesPromise} from 'types/ChangedFiles';
-import {getChangedFilesForRoots} from 'jest-changed-files';
+import {Config} from '@jest/types';
+import {getChangedFilesForRoots, ChangedFilesPromise} from 'jest-changed-files';
 import {formatExecError} from 'jest-message-util';
 import chalk from 'chalk';
 
 export default (
-  globalConfig: GlobalConfig,
-  configs: Array<ProjectConfig>,
-): ?ChangedFilesPromise => {
+  globalConfig: Config.GlobalConfig,
+  configs: Array<Config.ProjectConfig>,
+): ChangedFilesPromise | undefined => {
   if (globalConfig.onlyChanged) {
-    const allRootsForAllProjects = configs.reduce(
-      (roots, config) => roots.concat(config.roots || []),
+    const allRootsForAllProjects = configs.reduce<Array<Config.Path>>(
+      (roots, config) => [...roots, ...(config.roots || [])],
       [],
     );
     return getChangedFilesForRoots(allRootsForAllProjects, {
diff --git a/packages/jest-core/src/getNoTestFound.js b/packages/jest-core/src/getNoTestFound.ts
similarity index 84%
rename from packages/jest-core/src/getNoTestFound.js
rename to packages/jest-core/src/getNoTestFound.ts
index bd6ec71b13ac..d1fa85d3ec8e 100644
--- a/packages/jest-core/src/getNoTestFound.js
+++ b/packages/jest-core/src/getNoTestFound.ts
@@ -3,22 +3,19 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {GlobalConfig} from 'types/Config';
-import type {TestRunData} from 'types/TestRunner';
-
 import chalk from 'chalk';
+import {Config} from '@jest/types';
+import {TestRunData} from './types';
 import pluralize from './pluralize';
 
 export default function getNoTestFound(
   testRunData: TestRunData,
-  globalConfig: GlobalConfig,
+  globalConfig: Config.GlobalConfig,
 ): string {
   const testFiles = testRunData.reduce(
-    (current, testRun) => current + testRun.matches.total || 0,
+    (current, testRun) => current + (testRun.matches.total || 0),
     0,
   );
   let dataMessage;
diff --git a/packages/jest-core/src/getNoTestFoundFailed.js b/packages/jest-core/src/getNoTestFoundFailed.ts
similarity index 100%
rename from packages/jest-core/src/getNoTestFoundFailed.js
rename to packages/jest-core/src/getNoTestFoundFailed.ts
diff --git a/packages/jest-core/src/getNoTestFoundRelatedToChangedFiles.js b/packages/jest-core/src/getNoTestFoundRelatedToChangedFiles.ts
similarity index 80%
rename from packages/jest-core/src/getNoTestFoundRelatedToChangedFiles.js
rename to packages/jest-core/src/getNoTestFoundRelatedToChangedFiles.ts
index b78468c63cf4..4c3ecb74a56b 100644
--- a/packages/jest-core/src/getNoTestFoundRelatedToChangedFiles.js
+++ b/packages/jest-core/src/getNoTestFoundRelatedToChangedFiles.ts
@@ -1,9 +1,12 @@
 // Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
 
 import chalk from 'chalk';
+import {Config} from '@jest/types';
 import {isInteractive} from 'jest-util';
 
-export default function getNoTestFoundRelatedToChangedFiles(globalConfig) {
+export default function getNoTestFoundRelatedToChangedFiles(
+  globalConfig: Config.GlobalConfig,
+) {
   const ref = globalConfig.changedSince
     ? `"${globalConfig.changedSince}"`
     : 'last commit';
diff --git a/packages/jest-core/src/getNoTestFoundVerbose.js b/packages/jest-core/src/getNoTestFoundVerbose.ts
similarity index 78%
rename from packages/jest-core/src/getNoTestFoundVerbose.js
rename to packages/jest-core/src/getNoTestFoundVerbose.ts
index f0f503954ccd..e1389f7ef423 100644
--- a/packages/jest-core/src/getNoTestFoundVerbose.js
+++ b/packages/jest-core/src/getNoTestFoundVerbose.ts
@@ -1,24 +1,27 @@
 // Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
 
 import chalk from 'chalk';
+import {Config} from '@jest/types';
 import pluralize from './pluralize';
+import {Stats, TestRunData} from './types';
 
 export default function getNoTestFoundVerbose(
-  testRunData,
-  globalConfig,
+  testRunData: TestRunData,
+  globalConfig: Config.GlobalConfig,
 ): string {
   const individualResults = testRunData.map(testRun => {
-    const stats = testRun.matches.stats || {};
+    const stats = testRun.matches.stats || ({} as Stats);
     const config = testRun.context.config;
-    const statsMessage = Object.keys(stats)
+    const statsMessage = (Object.keys(stats) as Array<keyof Stats>)
       .map(key => {
         if (key === 'roots' && config.roots.length === 1) {
           return null;
         }
         const value = config[key];
         if (value) {
+          const valueAsString = Array.isArray(value) ? value.join(', ') : value;
           const matches = pluralize('match', stats[key], 'es');
-          return `  ${key}: ${chalk.yellow(value)} - ${matches}`;
+          return `  ${key}: ${chalk.yellow(valueAsString)} - ${matches}`;
         }
         return null;
       })
diff --git a/packages/jest-core/src/getNoTestsFoundMessage.js b/packages/jest-core/src/getNoTestsFoundMessage.ts
similarity index 86%
rename from packages/jest-core/src/getNoTestsFoundMessage.js
rename to packages/jest-core/src/getNoTestsFoundMessage.ts
index be2211172597..00b0b5e6148b 100644
--- a/packages/jest-core/src/getNoTestsFoundMessage.js
+++ b/packages/jest-core/src/getNoTestsFoundMessage.ts
@@ -3,13 +3,10 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {GlobalConfig} from 'types/Config';
-import type {TestRunData} from 'types/TestRunner';
-
+import {Config} from '@jest/types';
+import {TestRunData} from './types';
 import getNoTestFound from './getNoTestFound';
 import getNoTestFoundRelatedToChangedFiles from './getNoTestFoundRelatedToChangedFiles';
 import getNoTestFoundVerbose from './getNoTestFoundVerbose';
@@ -17,7 +14,7 @@ import getNoTestFoundFailed from './getNoTestFoundFailed';
 
 export default function getNoTestsFoundMessage(
   testRunData: TestRunData,
-  globalConfig: GlobalConfig,
+  globalConfig: Config.GlobalConfig,
 ): string {
   if (globalConfig.onlyFailures) {
     return getNoTestFoundFailed();
diff --git a/packages/jest-core/src/jest.js b/packages/jest-core/src/jest.ts
similarity index 97%
rename from packages/jest-core/src/jest.js
rename to packages/jest-core/src/jest.ts
index ca6fe2d0d479..87ceab84269f 100644
--- a/packages/jest-core/src/jest.js
+++ b/packages/jest-core/src/jest.ts
@@ -3,8 +3,6 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
 export {default as SearchSource} from './SearchSource';
diff --git a/packages/jest-core/src/lib/__tests__/__snapshots__/log_debug_messages.test.js.snap b/packages/jest-core/src/lib/__tests__/__snapshots__/log_debug_messages.test.js.snap
deleted file mode 100644
index 16e1a6040a64..000000000000
--- a/packages/jest-core/src/lib/__tests__/__snapshots__/log_debug_messages.test.js.snap
+++ /dev/null
@@ -1,45 +0,0 @@
-// Jest Snapshot v1, https://goo.gl/fbAQLP
-
-exports[`prints the config object 1`] = `
-"{
-  \\"configs\\": {
-    \\"rootDir\\": \\"/path/to/dir\\",
-    \\"roots\\": [
-      \\"path/to/dir/test\\"
-    ],
-    \\"testRunner\\": \\"myRunner\\"
-  },
-  \\"globalConfig\\": {
-    \\"automock\\": false,
-    \\"watch\\": true
-  },
-  \\"version\\": 123
-}
-"
-`;
-
-exports[`prints the jest version 1`] = `
-"{
-  \\"configs\\": {
-    \\"testRunner\\": \\"myRunner\\"
-  },
-  \\"globalConfig\\": {
-    \\"watch\\": true
-  },
-  \\"version\\": 123
-}
-"
-`;
-
-exports[`prints the test framework name 1`] = `
-"{
-  \\"configs\\": {
-    \\"testRunner\\": \\"myRunner\\"
-  },
-  \\"globalConfig\\": {
-    \\"watch\\": true
-  },
-  \\"version\\": 123
-}
-"
-`;
diff --git a/packages/jest-core/src/lib/__tests__/__snapshots__/log_debug_messages.test.ts.snap b/packages/jest-core/src/lib/__tests__/__snapshots__/log_debug_messages.test.ts.snap
new file mode 100644
index 000000000000..fc4ae3ee76e0
--- /dev/null
+++ b/packages/jest-core/src/lib/__tests__/__snapshots__/log_debug_messages.test.ts.snap
@@ -0,0 +1,126 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`prints the config object 1`] = `
+{
+  "configs": {
+    "automock": false,
+    "browser": false,
+    "cache": false,
+    "cacheDirectory": "/test_cache_dir/",
+    "clearMocks": false,
+    "coveragePathIgnorePatterns": [],
+    "cwd": "/test_root_dir/",
+    "detectLeaks": false,
+    "detectOpenHandles": false,
+    "errorOnDeprecated": false,
+    "extraGlobals": [],
+    "filter": null,
+    "forceCoverageMatch": [],
+    "globalSetup": null,
+    "globalTeardown": null,
+    "globals": {},
+    "haste": {
+      "providesModuleNodeModules": []
+    },
+    "moduleDirectories": [],
+    "moduleFileExtensions": [
+      "js"
+    ],
+    "moduleLoader": "/test_module_loader_path",
+    "moduleNameMapper": [],
+    "modulePathIgnorePatterns": [],
+    "modulePaths": [],
+    "name": "test_name",
+    "prettierPath": "prettier",
+    "resetMocks": false,
+    "resetModules": false,
+    "resolver": null,
+    "restoreMocks": false,
+    "rootDir": "/path/to/dir",
+    "roots": [
+      "path/to/dir/test"
+    ],
+    "runner": "jest-runner",
+    "setupFiles": [],
+    "setupFilesAfterEnv": [],
+    "skipFilter": false,
+    "skipNodeResolution": false,
+    "snapshotResolver": null,
+    "snapshotSerializers": [],
+    "testEnvironment": "node",
+    "testEnvironmentOptions": {},
+    "testLocationInResults": false,
+    "testMatch": [],
+    "testPathIgnorePatterns": [],
+    "testRegex": [
+      "\\\\.test\\\\.js$"
+    ],
+    "testRunner": "myRunner",
+    "testURL": "",
+    "timers": "real",
+    "transform": [],
+    "transformIgnorePatterns": [],
+    "unmockedModulePathPatterns": null,
+    "watchPathIgnorePatterns": []
+  },
+  "globalConfig": {
+    "bail": 0,
+    "changedFilesWithAncestor": false,
+    "changedSince": "",
+    "collectCoverage": false,
+    "collectCoverageFrom": [],
+    "collectCoverageOnlyFrom": null,
+    "coverageDirectory": "coverage",
+    "coverageReporters": [],
+    "coverageThreshold": {
+      "global": {}
+    },
+    "detectLeaks": false,
+    "detectOpenHandles": false,
+    "enabledTestsMap": null,
+    "errorOnDeprecated": false,
+    "expand": false,
+    "extraGlobals": [],
+    "filter": null,
+    "findRelatedTests": false,
+    "forceExit": false,
+    "globalSetup": null,
+    "globalTeardown": null,
+    "json": false,
+    "lastCommit": false,
+    "listTests": false,
+    "logHeapUsage": false,
+    "maxConcurrency": 5,
+    "maxWorkers": 2,
+    "noSCM": null,
+    "noStackTrace": false,
+    "nonFlagArgs": [],
+    "notify": false,
+    "notifyMode": "failure-change",
+    "onlyChanged": false,
+    "onlyFailures": false,
+    "outputFile": null,
+    "passWithNoTests": false,
+    "projects": [],
+    "replname": null,
+    "reporters": [],
+    "rootDir": "/test_root_dir/",
+    "runTestsByPath": false,
+    "silent": false,
+    "skipFilter": false,
+    "testFailureExitCode": 1,
+    "testNamePattern": "",
+    "testPathPattern": "",
+    "testResultsProcessor": null,
+    "updateSnapshot": "none",
+    "useStderr": false,
+    "verbose": false,
+    "watch": true,
+    "watchAll": false,
+    "watchPlugins": [],
+    "watchman": false
+  },
+  "version": 123
+}
+
+`;
diff --git a/packages/jest-core/src/lib/__tests__/is_valid_path.test.js b/packages/jest-core/src/lib/__tests__/is_valid_path.test.ts
similarity index 97%
rename from packages/jest-core/src/lib/__tests__/is_valid_path.test.js
rename to packages/jest-core/src/lib/__tests__/is_valid_path.test.ts
index 06320576c7c3..a0595df535e1 100644
--- a/packages/jest-core/src/lib/__tests__/is_valid_path.test.js
+++ b/packages/jest-core/src/lib/__tests__/is_valid_path.test.ts
@@ -3,13 +3,10 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import isValidPath from '../is_valid_path';
 import path from 'path';
-//$FlowFixMe: Converted to TS
+import isValidPath from '../is_valid_path';
 import {makeGlobalConfig} from '../../../../../TestUtils';
 
 const rootDir = path.resolve(path.sep, 'root');
diff --git a/packages/jest-core/src/lib/__tests__/log_debug_messages.test.js b/packages/jest-core/src/lib/__tests__/log_debug_messages.test.js
deleted file mode 100644
index 0827f195bd20..000000000000
--- a/packages/jest-core/src/lib/__tests__/log_debug_messages.test.js
+++ /dev/null
@@ -1,45 +0,0 @@
-/**
- * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- *
- */
-
-'use strict';
-
-import logDebugMessages from '../log_debug_messages';
-
-jest.mock('../../../package.json', () => ({version: 123}));
-
-jest.mock('myRunner', () => ({name: 'My Runner'}), {virtual: true});
-
-const getOutputStream = () => ({
-  write(message) {
-    expect(message).toMatchSnapshot();
-  },
-});
-
-it('prints the jest version', () => {
-  expect.assertions(1);
-  logDebugMessages({watch: true}, {testRunner: 'myRunner'}, getOutputStream());
-});
-
-it('prints the test framework name', () => {
-  expect.assertions(1);
-  logDebugMessages({watch: true}, {testRunner: 'myRunner'}, getOutputStream());
-});
-
-it('prints the config object', () => {
-  expect.assertions(1);
-  const globalConfig = {
-    automock: false,
-    watch: true,
-  };
-  const config = {
-    rootDir: '/path/to/dir',
-    roots: ['path/to/dir/test'],
-    testRunner: 'myRunner',
-  };
-  logDebugMessages(globalConfig, config, getOutputStream());
-});
diff --git a/packages/jest-core/src/lib/__tests__/log_debug_messages.test.ts b/packages/jest-core/src/lib/__tests__/log_debug_messages.test.ts
new file mode 100644
index 000000000000..036a1b0f0004
--- /dev/null
+++ b/packages/jest-core/src/lib/__tests__/log_debug_messages.test.ts
@@ -0,0 +1,65 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ */
+
+import {wrap} from 'jest-snapshot-serializer-raw';
+import logDebugMessages from '../log_debug_messages';
+import {makeGlobalConfig, makeProjectConfig} from '../../../../../TestUtils';
+
+jest.mock('../../../package.json', () => ({version: 123}));
+
+jest.mock('myRunner', () => ({name: 'My Runner'}), {virtual: true});
+
+const getOutputStream = (resolve: (message: string) => void) =>
+  ({
+    write(message: string) {
+      resolve(message);
+    },
+  } as NodeJS.WriteStream);
+
+it('prints the jest version', async () => {
+  expect.assertions(1);
+  const message = await new Promise<string>(resolve => {
+    logDebugMessages(
+      makeGlobalConfig({watch: true}),
+      makeProjectConfig({testRunner: 'myRunner'}),
+      getOutputStream(resolve),
+    );
+  });
+
+  expect(JSON.parse(message).version).toBe(123);
+});
+
+it('prints the test framework name', async () => {
+  expect.assertions(1);
+  const message = await new Promise<string>(resolve => {
+    logDebugMessages(
+      makeGlobalConfig({watch: true}),
+      makeProjectConfig({testRunner: 'myRunner'}),
+      getOutputStream(resolve),
+    );
+  });
+
+  expect(JSON.parse(message).configs.testRunner).toBe('myRunner');
+});
+
+it('prints the config object', async () => {
+  expect.assertions(1);
+  const globalConfig = makeGlobalConfig({
+    watch: true,
+  });
+  const config = makeProjectConfig({
+    automock: false,
+    rootDir: '/path/to/dir',
+    roots: ['path/to/dir/test'],
+    testRunner: 'myRunner',
+  });
+  const message = await new Promise<string>(resolve => {
+    logDebugMessages(globalConfig, config, getOutputStream(resolve));
+  });
+  expect(wrap(message)).toMatchSnapshot();
+});
diff --git a/packages/jest-core/src/lib/active_filters_message.js b/packages/jest-core/src/lib/active_filters_message.ts
similarity index 90%
rename from packages/jest-core/src/lib/active_filters_message.js
rename to packages/jest-core/src/lib/active_filters_message.ts
index b446c551d8c9..240fab05b574 100644
--- a/packages/jest-core/src/lib/active_filters_message.js
+++ b/packages/jest-core/src/lib/active_filters_message.ts
@@ -3,14 +3,13 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
-import type {GlobalConfig} from 'types/Config';
+
 import chalk from 'chalk';
+import {Config} from '@jest/types';
 
 const activeFilters = (
-  globalConfig: GlobalConfig,
+  globalConfig: Config.GlobalConfig,
   delimiter: string = '\n',
 ) => {
   const {testNamePattern, testPathPattern} = globalConfig;
diff --git a/packages/jest-core/src/lib/create_context.js b/packages/jest-core/src/lib/create_context.ts
similarity index 57%
rename from packages/jest-core/src/lib/create_context.js
rename to packages/jest-core/src/lib/create_context.ts
index 8fe14b4683c9..535a9c8e01fd 100644
--- a/packages/jest-core/src/lib/create_context.js
+++ b/packages/jest-core/src/lib/create_context.ts
@@ -3,19 +3,15 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {ProjectConfig} from 'types/Config';
-import type {Context} from 'types/Context';
-import type {HasteMap} from 'types/HasteMap';
-
-import Runtime from 'jest-runtime';
+import {Config} from '@jest/types';
+import Runtime, {Context} from 'jest-runtime';
+import {HasteMapObject} from 'jest-haste-map';
 
 export default (
-  config: ProjectConfig,
-  {hasteFS, moduleMap}: HasteMap,
+  config: Config.ProjectConfig,
+  {hasteFS, moduleMap}: HasteMapObject,
 ): Context => ({
   config,
   hasteFS,
diff --git a/packages/jest-core/src/lib/handle_deprecation_warnings.js b/packages/jest-core/src/lib/handle_deprecation_warnings.ts
similarity index 85%
rename from packages/jest-core/src/lib/handle_deprecation_warnings.js
rename to packages/jest-core/src/lib/handle_deprecation_warnings.ts
index e7778707f018..560352d5f23d 100644
--- a/packages/jest-core/src/lib/handle_deprecation_warnings.js
+++ b/packages/jest-core/src/lib/handle_deprecation_warnings.ts
@@ -3,16 +3,14 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
 import chalk from 'chalk';
 import {KEYS} from 'jest-watcher';
 
 export default (
-  pipe: stream$Writable | tty$WriteStream,
-  stdin: stream$Readable | tty$ReadStream = process.stdin,
+  pipe: NodeJS.WriteStream,
+  stdin: NodeJS.ReadStream = process.stdin,
 ): Promise<void> =>
   new Promise((resolve, reject) => {
     if (typeof stdin.setRawMode === 'function') {
@@ -24,11 +22,10 @@ export default (
 
       pipe.write(messages.join('\n'));
 
-      // $FlowFixMe
       stdin.setRawMode(true);
       stdin.resume();
       stdin.setEncoding('utf8');
-      stdin.on('data', (key: string) => {
+      stdin.on('data', key => {
         if (key === KEYS.ENTER) {
           resolve();
         } else if (
diff --git a/packages/jest-core/src/lib/is_valid_path.js b/packages/jest-core/src/lib/is_valid_path.ts
similarity index 78%
rename from packages/jest-core/src/lib/is_valid_path.js
rename to packages/jest-core/src/lib/is_valid_path.ts
index ffd14efb8fff..a836154b65e1 100644
--- a/packages/jest-core/src/lib/is_valid_path.js
+++ b/packages/jest-core/src/lib/is_valid_path.ts
@@ -3,16 +3,14 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {GlobalConfig} from 'types/Config';
+import {Config} from '@jest/types';
 import {isSnapshotPath} from 'jest-snapshot';
 
 export default function isValidPath(
-  globalConfig: GlobalConfig,
-  filePath: string,
+  globalConfig: Config.GlobalConfig,
+  filePath: Config.Path,
 ) {
   return (
     !filePath.includes(globalConfig.coverageDirectory) &&
diff --git a/packages/jest-core/src/lib/log_debug_messages.js b/packages/jest-core/src/lib/log_debug_messages.ts
similarity index 62%
rename from packages/jest-core/src/lib/log_debug_messages.js
rename to packages/jest-core/src/lib/log_debug_messages.ts
index d784960476b6..6ae3a51d1d4c 100644
--- a/packages/jest-core/src/lib/log_debug_messages.js
+++ b/packages/jest-core/src/lib/log_debug_messages.ts
@@ -3,18 +3,16 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {GlobalConfig, ProjectConfig} from 'types/Config';
+import {Config} from '@jest/types';
 
-import {version as VERSION} from '../../package.json';
+const VERSION = require('../../package.json').version;
 
 export default function logDebugMessages(
-  globalConfig: GlobalConfig,
-  configs: Array<ProjectConfig>,
-  outputStream: stream$Writable | tty$WriteStream,
+  globalConfig: Config.GlobalConfig,
+  configs: Array<Config.ProjectConfig> | Config.ProjectConfig,
+  outputStream: NodeJS.WriteStream,
 ): void {
   const output = {
     configs,
diff --git a/packages/jest-core/src/lib/update_global_config.js b/packages/jest-core/src/lib/update_global_config.ts
similarity index 66%
rename from packages/jest-core/src/lib/update_global_config.js
rename to packages/jest-core/src/lib/update_global_config.ts
index beee59cd77b5..3a0f2879338c 100644
--- a/packages/jest-core/src/lib/update_global_config.js
+++ b/packages/jest-core/src/lib/update_global_config.ts
@@ -3,42 +3,21 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
 import {replacePathSepForRegex} from 'jest-regex-util';
-
-import type {GlobalConfig} from 'types/Config';
-
-export type Options = {
-  bail?: $PropertyType<GlobalConfig, 'bail'>,
-  changedSince?: $PropertyType<GlobalConfig, 'changedSince'>,
-  collectCoverage?: $PropertyType<GlobalConfig, 'collectCoverage'>,
-  collectCoverageFrom?: $PropertyType<GlobalConfig, 'collectCoverageFrom'>,
-  collectCoverageOnlyFrom?: $PropertyType<
-    GlobalConfig,
-    'collectCoverageOnlyFrom',
-  >,
-  coverageDirectory?: $PropertyType<GlobalConfig, 'coverageDirectory'>,
-  coverageReporters?: $PropertyType<GlobalConfig, 'coverageReporters'>,
-  mode?: 'watch' | 'watchAll',
-  notify?: $PropertyType<GlobalConfig, 'notify'>,
-  notifyMode?: $PropertyType<GlobalConfig, 'notifyMode'>,
-  onlyFailures?: $PropertyType<GlobalConfig, 'onlyFailures'>,
-  reporters?: $PropertyType<GlobalConfig, 'reporters'>,
-  testNamePattern?: $PropertyType<GlobalConfig, 'testNamePattern'>,
-  testPathPattern?: $PropertyType<GlobalConfig, 'testPathPattern'>,
-  updateSnapshot?: $PropertyType<GlobalConfig, 'updateSnapshot'>,
-  verbose?: $PropertyType<GlobalConfig, 'verbose'>,
-};
-
-export default (globalConfig: GlobalConfig, options: Options): GlobalConfig => {
-  const newConfig: GlobalConfig = {...globalConfig};
-
-  if (!options) {
-    options = {};
-  }
+import {Config} from '@jest/types';
+import {AllowedConfigOptions} from 'jest-watcher';
+
+type ExtraConfigOptions = Partial<
+  Pick<Config.GlobalConfig, 'noSCM' | 'passWithNoTests'>
+>;
+
+export default (
+  globalConfig: Config.GlobalConfig,
+  options: AllowedConfigOptions & ExtraConfigOptions = {},
+): Config.GlobalConfig => {
+  const newConfig: Config.GlobalConfig = {...globalConfig};
 
   if (options.mode === 'watch') {
     newConfig.watch = true;
diff --git a/packages/jest-core/src/lib/watch_plugins_helpers.js b/packages/jest-core/src/lib/watch_plugins_helpers.ts
similarity index 72%
rename from packages/jest-core/src/lib/watch_plugins_helpers.js
rename to packages/jest-core/src/lib/watch_plugins_helpers.ts
index ad9fa58a9e9e..db43a6655026 100644
--- a/packages/jest-core/src/lib/watch_plugins_helpers.js
+++ b/packages/jest-core/src/lib/watch_plugins_helpers.ts
@@ -3,33 +3,37 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
-import type {GlobalConfig} from 'types/Config';
-import type {WatchPlugin, UsageData} from '../types';
+
+import {Config} from '@jest/types';
+import {WatchPlugin, UsageData} from 'jest-watcher';
 
 export const filterInteractivePlugins = (
   watchPlugins: Array<WatchPlugin>,
-  globalConfig: GlobalConfig,
+  globalConfig: Config.GlobalConfig,
 ): Array<WatchPlugin> => {
   const usageInfos = watchPlugins.map(
     p => p.getUsageInfo && p.getUsageInfo(globalConfig),
   );
 
-  return watchPlugins.filter((plugin, i, array) => {
-    if (usageInfos[i]) {
-      const {key} = usageInfos[i];
-      return !usageInfos.slice(i + 1).some(u => u && key === u.key);
+  return watchPlugins.filter((_plugin, i) => {
+    const usageInfo = usageInfos[i];
+    if (usageInfo) {
+      const {key} = usageInfo;
+      return !usageInfos.slice(i + 1).some(u => !!u && key === u.key);
     }
 
     return false;
   });
 };
 
+function notEmpty<T>(value: T | null | undefined): value is T {
+  return value != null;
+}
+
 export const getSortedUsageRows = (
   watchPlugins: Array<WatchPlugin>,
-  globalConfig: GlobalConfig,
+  globalConfig: Config.GlobalConfig,
 ): Array<UsageData> =>
   filterInteractivePlugins(watchPlugins, globalConfig)
     .sort((a: WatchPlugin, b: WatchPlugin) => {
@@ -52,4 +56,4 @@ export const getSortedUsageRows = (
       return 0;
     })
     .map(p => p.getUsageInfo && p.getUsageInfo(globalConfig))
-    .filter(Boolean);
+    .filter(notEmpty);
diff --git a/packages/jest-core/src/plugins/quit.js b/packages/jest-core/src/plugins/quit.ts
similarity index 83%
rename from packages/jest-core/src/plugins/quit.js
rename to packages/jest-core/src/plugins/quit.ts
index 68a336cf203e..462de025729c 100644
--- a/packages/jest-core/src/plugins/quit.js
+++ b/packages/jest-core/src/plugins/quit.ts
@@ -3,18 +3,14 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
+
 import {BaseWatchPlugin} from 'jest-watcher';
 
 class QuitPlugin extends BaseWatchPlugin {
   isInternal: true;
 
-  constructor(options: {
-    stdin: stream$Readable | tty$ReadStream,
-    stdout: stream$Writable | tty$WriteStream,
-  }) {
+  constructor(options: {stdin: NodeJS.ReadStream; stdout: NodeJS.WriteStream}) {
     super(options);
     this.isInternal = true;
   }
diff --git a/packages/jest-core/src/plugins/test_name_pattern.js b/packages/jest-core/src/plugins/test_name_pattern.ts
similarity index 78%
rename from packages/jest-core/src/plugins/test_name_pattern.js
rename to packages/jest-core/src/plugins/test_name_pattern.ts
index fa9c496a72f4..b16560337f11 100644
--- a/packages/jest-core/src/plugins/test_name_pattern.js
+++ b/packages/jest-core/src/plugins/test_name_pattern.ts
@@ -3,11 +3,10 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
-import type {GlobalConfig} from 'types/Config';
-import {BaseWatchPlugin, Prompt} from 'jest-watcher';
+
+import {Config} from '@jest/types';
+import {BaseWatchPlugin, Prompt, UpdateConfigCallback} from 'jest-watcher';
 import TestNamePatternPrompt from '../TestNamePatternPrompt';
 import activeFilters from '../lib/active_filters_message';
 
@@ -15,10 +14,7 @@ class TestNamePatternPlugin extends BaseWatchPlugin {
   _prompt: Prompt;
   isInternal: true;
 
-  constructor(options: {
-    stdin: stream$Readable | tty$ReadStream,
-    stdout: stream$Writable | tty$WriteStream,
-  }) {
+  constructor(options: {stdin: NodeJS.ReadStream; stdout: NodeJS.WriteStream}) {
     super(options);
     this._prompt = new Prompt();
     this.isInternal = true;
@@ -35,7 +31,10 @@ class TestNamePatternPlugin extends BaseWatchPlugin {
     this._prompt.put(key);
   }
 
-  run(globalConfig: GlobalConfig, updateConfigAndRun: Function): Promise<void> {
+  run(
+    globalConfig: Config.GlobalConfig,
+    updateConfigAndRun: UpdateConfigCallback,
+  ): Promise<void> {
     return new Promise((res, rej) => {
       const testNamePatternPrompt = new TestNamePatternPrompt(
         this._stdout,
diff --git a/packages/jest-core/src/plugins/test_path_pattern.js b/packages/jest-core/src/plugins/test_path_pattern.ts
similarity index 76%
rename from packages/jest-core/src/plugins/test_path_pattern.js
rename to packages/jest-core/src/plugins/test_path_pattern.ts
index 8bc9dfab7d96..aa37447fde83 100644
--- a/packages/jest-core/src/plugins/test_path_pattern.js
+++ b/packages/jest-core/src/plugins/test_path_pattern.ts
@@ -3,23 +3,18 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {GlobalConfig} from 'types/Config';
-import {BaseWatchPlugin, Prompt} from 'jest-watcher';
+import {Config} from '@jest/types';
+import {BaseWatchPlugin, Prompt, UpdateConfigCallback} from 'jest-watcher';
 import TestPathPatternPrompt from '../TestPathPatternPrompt';
 import activeFilters from '../lib/active_filters_message';
 
 class TestPathPatternPlugin extends BaseWatchPlugin {
-  _prompt: Prompt;
+  private _prompt: Prompt;
   isInternal: true;
 
-  constructor(options: {
-    stdin: stream$Readable | tty$ReadStream,
-    stdout: stream$Writable | tty$WriteStream,
-  }) {
+  constructor(options: {stdin: NodeJS.ReadStream; stdout: NodeJS.WriteStream}) {
     super(options);
     this._prompt = new Prompt();
     this.isInternal = true;
@@ -36,7 +31,10 @@ class TestPathPatternPlugin extends BaseWatchPlugin {
     this._prompt.put(key);
   }
 
-  run(globalConfig: GlobalConfig, updateConfigAndRun: Function): Promise<void> {
+  run(
+    globalConfig: Config.GlobalConfig,
+    updateConfigAndRun: UpdateConfigCallback,
+  ): Promise<void> {
     return new Promise((res, rej) => {
       const testPathPatternPrompt = new TestPathPatternPrompt(
         this._stdout,
diff --git a/packages/jest-core/src/plugins/update_snapshots.js b/packages/jest-core/src/plugins/update_snapshots.ts
similarity index 65%
rename from packages/jest-core/src/plugins/update_snapshots.js
rename to packages/jest-core/src/plugins/update_snapshots.ts
index eb2fca1577cc..7007ac413c6c 100644
--- a/packages/jest-core/src/plugins/update_snapshots.js
+++ b/packages/jest-core/src/plugins/update_snapshots.ts
@@ -3,28 +3,28 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
-import type {GlobalConfig} from 'types/Config';
-import type {JestHookSubscriber} from 'types/JestHooks';
-import {BaseWatchPlugin} from 'jest-watcher';
+
+import {Config} from '@jest/types';
+import {
+  BaseWatchPlugin,
+  JestHookSubscriber,
+  UpdateConfigCallback,
+} from 'jest-watcher';
 
 class UpdateSnapshotsPlugin extends BaseWatchPlugin {
-  _hasSnapshotFailure: boolean;
+  private _hasSnapshotFailure: boolean;
   isInternal: true;
 
-  constructor(options: {
-    stdin: stream$Readable | tty$ReadStream,
-    stdout: stream$Writable | tty$WriteStream,
-  }) {
+  constructor(options: {stdin: NodeJS.ReadStream; stdout: NodeJS.WriteStream}) {
     super(options);
     this.isInternal = true;
+    this._hasSnapshotFailure = false;
   }
 
   run(
-    globalConfig: GlobalConfig,
-    updateConfigAndRun: Function,
+    _globalConfig: Config.GlobalConfig,
+    updateConfigAndRun: UpdateConfigCallback,
   ): Promise<boolean> {
     updateConfigAndRun({updateSnapshot: 'all'});
     return Promise.resolve(false);
@@ -36,7 +36,7 @@ class UpdateSnapshotsPlugin extends BaseWatchPlugin {
     });
   }
 
-  getUsageInfo(globalConfig: GlobalConfig) {
+  getUsageInfo() {
     if (this._hasSnapshotFailure) {
       return {
         key: 'u',
diff --git a/packages/jest-core/src/plugins/update_snapshots_interactive.js b/packages/jest-core/src/plugins/update_snapshots_interactive.ts
similarity index 75%
rename from packages/jest-core/src/plugins/update_snapshots_interactive.js
rename to packages/jest-core/src/plugins/update_snapshots_interactive.ts
index 0a293895e83e..29f2cac10bce 100644
--- a/packages/jest-core/src/plugins/update_snapshots_interactive.js
+++ b/packages/jest-core/src/plugins/update_snapshots_interactive.ts
@@ -3,25 +3,18 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
-import type {JestHookSubscriber} from 'types/JestHooks';
-import type {GlobalConfig} from 'types/Config';
-import type {AggregatedResult, AssertionLocation} from 'types/TestResult';
-import {BaseWatchPlugin} from 'jest-watcher';
+
+import {Config, TestResult} from '@jest/types';
+import {BaseWatchPlugin, JestHookSubscriber} from 'jest-watcher';
 import SnapshotInteractiveMode from '../SnapshotInteractiveMode';
 
 class UpdateSnapshotInteractivePlugin extends BaseWatchPlugin {
-  _snapshotInteractiveMode: SnapshotInteractiveMode;
-  _failedSnapshotTestPaths: Array<*>;
-  _failedSnapshotTestAssertions: Array<AssertionLocation>;
+  private _snapshotInteractiveMode: SnapshotInteractiveMode;
+  private _failedSnapshotTestAssertions: Array<TestResult.AssertionLocation>;
   isInternal: true;
 
-  constructor(options: {
-    stdin: stream$Readable | tty$ReadStream,
-    stdout: stream$Writable | tty$WriteStream,
-  }) {
+  constructor(options: {stdin: NodeJS.ReadStream; stdout: NodeJS.WriteStream}) {
     super(options);
     this._failedSnapshotTestAssertions = [];
     this._snapshotInteractiveMode = new SnapshotInteractiveMode(this._stdout);
@@ -29,9 +22,9 @@ class UpdateSnapshotInteractivePlugin extends BaseWatchPlugin {
   }
 
   getFailedSnapshotTestAssertions(
-    testResults: AggregatedResult,
-  ): Array<AssertionLocation> {
-    const failedTestPaths = [];
+    testResults: TestResult.AggregatedResult,
+  ): Array<TestResult.AssertionLocation> {
+    const failedTestPaths: Array<TestResult.AssertionLocation> = [];
     if (testResults.numFailedTests === 0 || !testResults.testResults) {
       return failedTestPaths;
     }
@@ -69,12 +62,15 @@ class UpdateSnapshotInteractivePlugin extends BaseWatchPlugin {
     }
   }
 
-  run(globalConfig: GlobalConfig, updateConfigAndRun: Function): Promise<void> {
+  run(
+    _globalConfig: Config.GlobalConfig,
+    updateConfigAndRun: Function,
+  ): Promise<void> {
     if (this._failedSnapshotTestAssertions.length) {
       return new Promise(res => {
         this._snapshotInteractiveMode.run(
           this._failedSnapshotTestAssertions,
-          (assertion: ?AssertionLocation, shouldUpdateSnapshot: boolean) => {
+          (assertion, shouldUpdateSnapshot) => {
             updateConfigAndRun({
               mode: 'watch',
               testNamePattern: assertion ? `^${assertion.fullName}$` : '',
@@ -93,7 +89,7 @@ class UpdateSnapshotInteractivePlugin extends BaseWatchPlugin {
     }
   }
 
-  getUsageInfo(globalConfig: GlobalConfig) {
+  getUsageInfo() {
     if (
       this._failedSnapshotTestAssertions &&
       this._failedSnapshotTestAssertions.length > 0
diff --git a/packages/jest-core/src/pluralize.js b/packages/jest-core/src/pluralize.ts
similarity index 100%
rename from packages/jest-core/src/pluralize.js
rename to packages/jest-core/src/pluralize.ts
diff --git a/packages/jest-core/src/runGlobalHook.js b/packages/jest-core/src/runGlobalHook.ts
similarity index 82%
rename from packages/jest-core/src/runGlobalHook.js
rename to packages/jest-core/src/runGlobalHook.ts
index 6c89f943f4f0..32ba09112ec7 100644
--- a/packages/jest-core/src/runGlobalHook.js
+++ b/packages/jest-core/src/runGlobalHook.ts
@@ -3,31 +3,28 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {GlobalConfig} from 'types/Config';
-import type {Test} from 'types/TestRunner';
-
 import {extname} from 'path';
 import pEachSeries from 'p-each-series';
 import {addHook} from 'pirates';
+import {Config} from '@jest/types';
+import {Test} from 'jest-runner';
 import {ScriptTransformer} from '@jest/transform';
 
 // copied from https://github.com/babel/babel/blob/56044c7851d583d498f919e9546caddf8f80a72f/packages/babel-helpers/src/helpers.js#L558-L562
-function _interopRequireDefault(obj) {
+function _interopRequireDefault(obj: any) {
   return obj && obj.__esModule ? obj : {default: obj};
 }
 
-export default ({
+export default async ({
   allTests,
   globalConfig,
   moduleName,
 }: {
-  allTests: Array<Test>,
-  globalConfig: GlobalConfig,
-  moduleName: 'globalSetup' | 'globalTeardown',
+  allTests: Array<Test>;
+  globalConfig: Config.GlobalConfig;
+  moduleName: 'globalSetup' | 'globalTeardown';
 }): Promise<void> => {
   const globalModulePaths = new Set(
     allTests.map(test => test.context.config[moduleName]),
@@ -38,7 +35,7 @@ export default ({
   }
 
   if (globalModulePaths.size > 0) {
-    return pEachSeries(Array.from(globalModulePaths), async modulePath => {
+    await pEachSeries(Array.from(globalModulePaths), async modulePath => {
       if (!modulePath) {
         return;
       }
@@ -63,11 +60,10 @@ export default ({
           transformer.transformSource(filename, code, false).code || code,
         {
           exts: [extname(modulePath)],
-          matcher: transformer._shouldTransform.bind(transformer),
+          matcher: transformer.shouldTransform.bind(transformer),
         },
       );
 
-      // $FlowFixMe
       const globalModule = _interopRequireDefault(require(modulePath)).default;
 
       if (typeof globalModule !== 'function') {
diff --git a/packages/jest-core/src/runJest.js b/packages/jest-core/src/runJest.ts
similarity index 76%
rename from packages/jest-core/src/runJest.js
rename to packages/jest-core/src/runJest.ts
index a403ac57ca8a..e6f7e16e6d96 100644
--- a/packages/jest-core/src/runJest.js
+++ b/packages/jest-core/src/runJest.ts
@@ -3,41 +3,36 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {Context} from 'types/Context';
-import type {ChangedFilesPromise} from 'types/ChangedFiles';
-import type {GlobalConfig} from 'types/Config';
-import type {AggregatedResult} from 'types/TestResult';
-import type {TestRunData} from 'types/TestRunner';
-import type {JestHookEmitter} from 'types/JestHooks';
-import type TestWatcher from './TestWatcher';
-import type {TestSchedulerContext} from './TestScheduler';
-
-import chalk from 'chalk';
 import path from 'path';
+import chalk from 'chalk';
 import {sync as realpath} from 'realpath-native';
 import {Console, formatTestResults} from 'jest-util';
 import exit from 'exit';
 import fs from 'graceful-fs';
+import {JestHook, JestHookEmitter} from 'jest-watcher';
+import {Context} from 'jest-runtime';
+import {Test} from 'jest-runner';
+import {Config, TestResult} from '@jest/types';
+import {ChangedFiles, ChangedFilesPromise} from 'jest-changed-files';
 import getNoTestsFoundMessage from './getNoTestsFoundMessage';
 import runGlobalHook from './runGlobalHook';
 import SearchSource from './SearchSource';
-import TestScheduler from './TestScheduler';
+import TestScheduler, {TestSchedulerContext} from './TestScheduler';
 import TestSequencer from './TestSequencer';
 import {makeEmptyAggregatedTestResult} from './testResultHelpers';
 import FailedTestsCache from './FailedTestsCache';
-import {JestHook} from 'jest-watcher';
 import collectNodeHandles from './collectHandles';
+import TestWatcher from './TestWatcher';
+import {TestRunData} from './types';
 
 const getTestPaths = async (
-  globalConfig,
-  context,
-  outputStream,
-  changedFiles,
-  jestHooks,
+  globalConfig: Config.GlobalConfig,
+  context: Context,
+  outputStream: NodeJS.WritableStream,
+  changedFiles: ChangedFiles | undefined,
+  jestHooks: JestHookEmitter,
 ) => {
   const source = new SearchSource(context);
   const data = await source.getTestPaths(globalConfig, changedFiles);
@@ -62,15 +57,27 @@ const getTestPaths = async (
     ),
   );
 
-  const filteredTests = data.tests.filter((test, i) => shouldTestArray[i]);
+  const filteredTests = data.tests.filter((_test, i) => shouldTestArray[i]);
 
   return {...data, allTests: filteredTests.length, tests: filteredTests};
 };
 
-const processResults = (runResults, options) => {
+type ProcessResultOptions = Pick<
+  Config.GlobalConfig,
+  'json' | 'outputFile' | 'testResultsProcessor'
+> & {
+  collectHandles?: () => Array<Error>;
+  onComplete?: (result: TestResult.AggregatedResult) => void;
+  outputStream: NodeJS.WritableStream;
+};
+
+const processResults = (
+  runResults: TestResult.AggregatedResult,
+  options: ProcessResultOptions,
+) => {
   const {
     outputFile,
-    isJSON,
+    json: isJSON,
     onComplete,
     outputStream,
     testResultsProcessor,
@@ -84,7 +91,6 @@ const processResults = (runResults, options) => {
   }
 
   if (testResultsProcessor) {
-    /* $FlowFixMe */
     runResults = require(testResultsProcessor)(runResults);
   }
   if (isJSON) {
@@ -120,23 +126,25 @@ export default (async function runJest({
   onComplete,
   failedTestsCache,
 }: {
-  globalConfig: GlobalConfig,
-  contexts: Array<Context>,
-  outputStream: stream$Writable | tty$WriteStream,
-  testWatcher: TestWatcher,
-  jestHooks?: JestHookEmitter,
-  startRun: (globalConfig: GlobalConfig) => *,
-  changedFilesPromise: ?ChangedFilesPromise,
-  onComplete: (testResults: AggregatedResult) => any,
-  failedTestsCache: ?FailedTestsCache,
+  globalConfig: Config.GlobalConfig;
+  contexts: Array<Context>;
+  outputStream: NodeJS.WritableStream;
+  testWatcher: TestWatcher;
+  jestHooks?: JestHookEmitter;
+  startRun: (globalConfig: Config.GlobalConfig) => void;
+  changedFilesPromise?: ChangedFilesPromise;
+  onComplete: (testResults: TestResult.AggregatedResult) => void;
+  failedTestsCache?: FailedTestsCache;
 }) {
   const sequencer = new TestSequencer();
-  let allTests = [];
+  let allTests: Array<Test> = [];
 
   if (changedFilesPromise && globalConfig.watch) {
     const {repos} = await changedFilesPromise;
 
-    const noSCM = Object.keys(repos).every(scm => repos[scm].size === 0);
+    const noSCM = (Object.keys(repos) as Array<
+      keyof ChangedFiles['repos']
+    >).every(scm => repos[scm].size === 0);
     if (noSCM) {
       process.stderr.write(
         '\n' +
@@ -207,7 +215,7 @@ export default (async function runJest({
     globalConfig.silent !== true &&
     globalConfig.verbose !== false
   ) {
-    const newConfig: GlobalConfig = {...globalConfig, verbose: true};
+    const newConfig: Config.GlobalConfig = {...globalConfig, verbose: true};
     globalConfig = Object.freeze(newConfig);
   }
 
@@ -227,9 +235,7 @@ export default (async function runJest({
 
   const results = await new TestScheduler(
     globalConfig,
-    {
-      startRun,
-    },
+    {startRun},
     testSchedulerContext,
   ).scheduleTests(allTests, testWatcher);
 
@@ -241,7 +247,7 @@ export default (async function runJest({
 
   return processResults(results, {
     collectHandles,
-    isJSON: globalConfig.json,
+    json: globalConfig.json,
     onComplete,
     outputFile: globalConfig.outputFile,
     outputStream,
diff --git a/packages/jest-core/src/testResultHelpers.js b/packages/jest-core/src/testResultHelpers.ts
similarity index 92%
rename from packages/jest-core/src/testResultHelpers.js
rename to packages/jest-core/src/testResultHelpers.ts
index cd534c243089..ffbebe101de9 100644
--- a/packages/jest-core/src/testResultHelpers.js
+++ b/packages/jest-core/src/testResultHelpers.ts
@@ -3,17 +3,11 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {
-  AggregatedResult,
-  SerializableError,
-  TestResult,
-} from 'types/TestResult';
+import {Config, TestResult} from '@jest/types';
 
-export const makeEmptyAggregatedTestResult = (): AggregatedResult => ({
+export const makeEmptyAggregatedTestResult = (): TestResult.AggregatedResult => ({
   numFailedTestSuites: 0,
   numFailedTests: 0,
   numPassedTestSuites: 0,
@@ -48,9 +42,9 @@ export const makeEmptyAggregatedTestResult = (): AggregatedResult => ({
 });
 
 export const buildFailureTestResult = (
-  testPath: string,
-  err: SerializableError,
-): TestResult => ({
+  testPath: Config.Path,
+  err: TestResult.SerializableError,
+): TestResult.TestResult => ({
   console: null,
   displayName: '',
   failureMessage: null,
@@ -82,8 +76,8 @@ export const buildFailureTestResult = (
 
 // Add individual test result to an aggregated test result
 export const addResult = (
-  aggregatedResults: AggregatedResult,
-  testResult: TestResult,
+  aggregatedResults: TestResult.AggregatedResult,
+  testResult: TestResult.TestResult,
 ): void => {
   // `todos` are new as of Jest 24, and not all runners return it.
   // Set it to `0` to avoid `NaN`
diff --git a/packages/jest-core/src/testSchedulerHelper.js b/packages/jest-core/src/testSchedulerHelper.ts
similarity index 93%
rename from packages/jest-core/src/testSchedulerHelper.js
rename to packages/jest-core/src/testSchedulerHelper.ts
index 37e22810f945..bb433f1e5367 100644
--- a/packages/jest-core/src/testSchedulerHelper.js
+++ b/packages/jest-core/src/testSchedulerHelper.ts
@@ -3,11 +3,9 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
-'use strict';
-import type {Test} from 'types/TestRunner';
+
+import {Test} from 'jest-runner';
 
 const SLOW_TEST_TIME = 1000;
 
@@ -15,7 +13,7 @@ export function shouldRunInBand(
   tests: Array<Test>,
   isWatchMode: boolean,
   maxWorkers: number,
-  timings: number[],
+  timings: Array<number>,
 ) {
   // Run in band if we only have one test or one worker available, unless we
   // are using the watch mode, in which case the TTY has to be responsive and
diff --git a/packages/jest-core/src/types.js b/packages/jest-core/src/types.js
deleted file mode 100644
index 35f8bd0ef357..000000000000
--- a/packages/jest-core/src/types.js
+++ /dev/null
@@ -1,26 +0,0 @@
-/**
- * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- *
- * @flow
- */
-import type {GlobalConfig} from 'types/Config';
-import type {JestHookSubscriber} from 'types/JestHooks';
-
-export type UsageData = {
-  key: string,
-  prompt: string,
-};
-
-export interface WatchPlugin {
-  +isInternal?: boolean;
-  +apply?: (hooks: JestHookSubscriber) => void;
-  +getUsageInfo?: (globalConfig: GlobalConfig) => ?UsageData;
-  +onKey?: (value: string) => void;
-  +run?: (
-    globalConfig: GlobalConfig,
-    updateConfigAndRun: Function,
-  ) => Promise<void | boolean>;
-}
diff --git a/packages/jest-core/src/types.ts b/packages/jest-core/src/types.ts
new file mode 100644
index 000000000000..debd9af8d73a
--- /dev/null
+++ b/packages/jest-core/src/types.ts
@@ -0,0 +1,64 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {Context} from 'jest-runtime';
+import {Test} from 'jest-runner';
+import {Config, TestResult} from '@jest/types';
+
+export type TestRunData = Array<{
+  context: Context;
+  matches: {
+    allTests: number;
+    tests: Array<Test>;
+    total?: number;
+    stats?: Stats;
+  };
+}>;
+
+type TestPathCaseStats = Record<keyof (TestPathCases), number>;
+
+export type TestPathCaseWithPathPatternStats = Record<
+  keyof (TestPathCasesWithPathPattern),
+  number
+>;
+
+export type Stats = TestPathCaseStats | TestPathCaseWithPathPatternStats;
+
+export type TestPathCases = {
+  roots: (path: Config.Path) => boolean;
+  testMatch: (path: Config.Path) => boolean;
+  testPathIgnorePatterns: (path: Config.Path) => boolean;
+  testRegex: (path: Config.Path) => boolean;
+};
+
+export type TestPathCasesWithPathPattern = TestPathCases & {
+  testPathPattern: (path: Config.Path) => boolean;
+};
+
+// TODO: Obtain this from @jest/reporters once its been migrated
+export type ReporterOnStartOptions = {
+  estimatedTime: number;
+  showStatus: boolean;
+};
+
+export type Reporter = {
+  onTestResult: (
+    test: Test,
+    testResult: TestResult.TestResult,
+    aggregatedResult: TestResult.AggregatedResult,
+  ) => Promise<void>;
+  onRunStart: (
+    results: TestResult.AggregatedResult,
+    options: ReporterOnStartOptions,
+  ) => Promise<void>;
+  onTestStart: (test: Test) => Promise<void>;
+  onRunComplete: (
+    contexts: Set<Context>,
+    results: TestResult.AggregatedResult,
+  ) => Promise<void>;
+  getLastError: () => Error;
+};
diff --git a/packages/jest-core/src/watch.js b/packages/jest-core/src/watch.ts
similarity index 85%
rename from packages/jest-core/src/watch.js
rename to packages/jest-core/src/watch.ts
index f630f8b085a4..4aa5da965b59 100644
--- a/packages/jest-core/src/watch.js
+++ b/packages/jest-core/src/watch.ts
@@ -3,30 +3,32 @@
  *
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
- *
- * @flow
  */
 
-import type {GlobalConfig} from 'types/Config';
-import type {Context} from 'types/Context';
-import type {WatchPlugin} from './types';
-import type {Options as UpdateGlobalConfigOptions} from './lib/update_global_config';
-
 import ansiEscapes from 'ansi-escapes';
 import chalk from 'chalk';
-import getChangedFilesPromise from './getChangedFilesPromise';
 import exit from 'exit';
-import HasteMap from 'jest-haste-map';
+import HasteMap, {HasteChangeEvent} from 'jest-haste-map';
 import {formatExecError} from 'jest-message-util';
-import isValidPath from './lib/is_valid_path';
 import {isInteractive, preRunMessage, specialChars} from 'jest-util';
+import {ValidationError} from 'jest-validate';
+import {Context} from 'jest-runtime';
+import {Config} from '@jest/types';
+import {
+  AllowedConfigOptions,
+  KEYS,
+  JestHook,
+  WatchPlugin,
+  WatchPluginClass,
+} from 'jest-watcher';
+import getChangedFilesPromise from './getChangedFilesPromise';
+import isValidPath from './lib/is_valid_path';
 import createContext from './lib/create_context';
 import runJest from './runJest';
 import updateGlobalConfig from './lib/update_global_config';
 import SearchSource from './SearchSource';
 import TestWatcher from './TestWatcher';
 import FailedTestsCache from './FailedTestsCache';
-import {KEYS, JestHook} from 'jest-watcher';
 import TestPathPatternPlugin from './plugins/test_path_pattern';
 import TestNamePatternPlugin from './plugins/test_name_pattern';
 import UpdateSnapshotsPlugin from './plugins/update_snapshots';
@@ -36,9 +38,17 @@ import {
   getSortedUsageRows,
   filterInteractivePlugins,
 } from './lib/watch_plugins_helpers';
-import {ValidationError} from 'jest-validate';
 import activeFilters from './lib/active_filters_message';
 
+type ReservedInfo = {
+  forbiddenOverwriteMessage?: string;
+  key?: string;
+  overwritable: boolean;
+  plugin: WatchPlugin;
+};
+
+type WatchPluginKeysMap = Map<string, ReservedInfo>;
+
 const {print: preRunMessagePrint} = preRunMessage;
 
 let hasExitListener = false;
@@ -51,7 +61,10 @@ const INTERNAL_PLUGINS = [
   QuitPlugin,
 ];
 
-const RESERVED_KEY_PLUGINS = new Map([
+const RESERVED_KEY_PLUGINS = new Map<
+  WatchPluginClass,
+  Pick<ReservedInfo, 'forbiddenOverwriteMessage' | 'key'>
+>([
   [
     UpdateSnapshotsPlugin,
     {forbiddenOverwriteMessage: 'updating snapshots', key: 'u'},
@@ -64,17 +77,17 @@ const RESERVED_KEY_PLUGINS = new Map([
 ]);
 
 export default function watch(
-  initialGlobalConfig: GlobalConfig,
+  initialGlobalConfig: Config.GlobalConfig,
   contexts: Array<Context>,
-  outputStream: stream$Writable | tty$WriteStream,
+  outputStream: NodeJS.WriteStream,
   hasteMapInstances: Array<HasteMap>,
-  stdin?: stream$Readable | tty$ReadStream = process.stdin,
-  hooks?: JestHook = new JestHook(),
+  stdin: NodeJS.ReadStream = process.stdin,
+  hooks: JestHook = new JestHook(),
 ): Promise<void> {
   // `globalConfig` will be constantly updated and reassigned as a result of
   // watch mode interactions.
   let globalConfig = initialGlobalConfig;
-  let activePlugin: ?WatchPlugin;
+  let activePlugin: WatchPlugin | null;
 
   globalConfig = updateGlobalConfig(globalConfig, {
     mode: globalConfig.watch ? 'watch' : 'watchAll',
@@ -98,7 +111,7 @@ export default function watch(
     testPathPattern,
     updateSnapshot,
     verbose,
-  }: UpdateGlobalConfigOptions = {}) => {
+  }: AllowedConfigOptions = {}) => {
     const previousUpdateSnapshot = globalConfig.updateSnapshot;
     globalConfig = updateGlobalConfig(globalConfig, {
       bail,
@@ -138,9 +151,11 @@ export default function watch(
   });
 
   if (globalConfig.watchPlugins != null) {
-    const watchPluginKeys = new Map();
+    const watchPluginKeys: WatchPluginKeysMap = new Map();
     for (const plugin of watchPlugins) {
-      const reservedInfo = RESERVED_KEY_PLUGINS.get(plugin.constructor) || {};
+      const reservedInfo =
+        RESERVED_KEY_PLUGINS.get(plugin.constructor as WatchPluginClass) ||
+        ({} as ReservedInfo);
       const key = reservedInfo.key || getPluginKey(plugin, globalConfig);
       if (!key) {
         continue;
@@ -154,7 +169,6 @@ export default function watch(
     }
 
     for (const pluginWithConfig of globalConfig.watchPlugins) {
-      // $FlowFixMe dynamic require
       const ThirdPartyPlugin = require(pluginWithConfig.path);
       const plugin: WatchPlugin = new ThirdPartyPlugin({
         config: pluginWithConfig.config,
@@ -177,7 +191,7 @@ export default function watch(
     searchSource: new SearchSource(context),
   }));
   let isRunning = false;
-  let testWatcher;
+  let testWatcher: TestWatcher;
   let shouldDisplayWatchUsage = true;
   let isWatchUsageDisplayed = false;
 
@@ -194,46 +208,49 @@ export default function watch(
   emitFileChange();
 
   hasteMapInstances.forEach((hasteMapInstance, index) => {
-    hasteMapInstance.on('change', ({eventsQueue, hasteFS, moduleMap}) => {
-      const validPaths = eventsQueue.filter(({filePath}) =>
-        isValidPath(globalConfig, filePath),
-      );
-
-      if (validPaths.length) {
-        const context = (contexts[index] = createContext(
-          contexts[index].config,
-          {
-            hasteFS,
-            moduleMap,
-          },
-        ));
-
-        activePlugin = null;
+    hasteMapInstance.on(
+      'change',
+      ({eventsQueue, hasteFS, moduleMap}: HasteChangeEvent) => {
+        const validPaths = eventsQueue.filter(({filePath}) =>
+          isValidPath(globalConfig, filePath),
+        );
 
-        searchSources = searchSources.slice();
-        searchSources[index] = {
-          context,
-          searchSource: new SearchSource(context),
-        };
-        emitFileChange();
-        startRun(globalConfig);
-      }
-    });
+        if (validPaths.length) {
+          const context = (contexts[index] = createContext(
+            contexts[index].config,
+            {hasteFS, moduleMap},
+          ));
+
+          activePlugin = null;
+
+          searchSources = searchSources.slice();
+          searchSources[index] = {
+            context,
+            searchSource: new SearchSource(context),
+          };
+          emitFileChange();
+          startRun(globalConfig);
+        }
+      },
+    );
   });
 
   if (!hasExitListener) {
     hasExitListener = true;
     process.on('exit', () => {
       if (activePlugin) {
+        // @ts-ignore: https://github.com/DefinitelyTyped/DefinitelyTyped/pull/33423
         outputStream.write(ansiEscapes.cursorDown());
         outputStream.write(ansiEscapes.eraseDown);
       }
     });
   }
 
-  const startRun = (globalConfig: GlobalConfig) => {
+  const startRun = (
+    globalConfig: Config.GlobalConfig,
+  ): Promise<void | null> => {
     if (isRunning) {
-      return null;
+      return Promise.resolve(null);
     }
 
     testWatcher = new TestWatcher({isWatchMode: true});
@@ -292,7 +309,6 @@ export default function watch(
   const onKeypress = (key: string) => {
     if (key === KEYS.CONTROL_C || key === KEYS.CONTROL_D) {
       if (typeof stdin.setRawMode === 'function') {
-        // $FlowFixMe
         stdin.setRawMode(false);
       }
       outputStream.write('\n');
@@ -388,6 +404,7 @@ export default function watch(
         break;
       case 'w':
         if (!shouldDisplayWatchUsage && !isWatchUsageDisplayed) {
+          // @ts-ignore: https://github.com/DefinitelyTyped/DefinitelyTyped/pull/33423
           outputStream.write(ansiEscapes.cursorUp());
           outputStream.write(ansiEscapes.eraseDown);
           outputStream.write(usage(globalConfig, watchPlugins));
@@ -406,7 +423,6 @@ export default function watch(
   };
 
   if (typeof stdin.setRawMode === 'function') {
-    // $FlowFixMe
     stdin.setRawMode(true);
     stdin.resume();
     stdin.setEncoding('utf8');
@@ -417,7 +433,11 @@ export default function watch(
   return Promise.resolve();
 }
 
-const checkForConflicts = (watchPluginKeys, plugin, globalConfig) => {
+const checkForConflicts = (
+  watchPluginKeys: WatchPluginKeysMap,
+  plugin: WatchPlugin,
+  globalConfig: Config.GlobalConfig,
+) => {
   const key = getPluginKey(plugin, globalConfig);
   if (!key) {
     return;
@@ -456,24 +476,27 @@ const checkForConflicts = (watchPluginKeys, plugin, globalConfig) => {
   throw new ValidationError('Watch plugin configuration error', error);
 };
 
-const getPluginIdentifier = plugin =>
+const getPluginIdentifier = (plugin: WatchPlugin) =>
   // This breaks as `displayName` is not defined as a static, but since
   // WatchPlugin is an interface, and it is my understanding interface
   // static fields are not definable anymore, no idea how to circumvent
   // this :-(
-  // $FlowFixMe: leave `displayName` be.
+  // @ts-ignore: leave `displayName` be.
   plugin.constructor.displayName || plugin.constructor.name;
 
-const getPluginKey = (plugin, globalConfig) => {
+const getPluginKey = (
+  plugin: WatchPlugin,
+  globalConfig: Config.GlobalConfig,
+) => {
   if (typeof plugin.getUsageInfo === 'function') {
-    return (plugin.getUsageInfo(globalConfig) || {}).key;
+    return (plugin.getUsageInfo(globalConfig) || {key: null}).key;
   }
 
   return null;
 };
 
 const usage = (
-  globalConfig,
+  globalConfig: Config.GlobalConfig,
   watchPlugins: Array<WatchPlugin>,
   delimiter = '\n',
 ) => {
diff --git a/packages/jest-core/tsconfig.json b/packages/jest-core/tsconfig.json
new file mode 100644
index 000000000000..3e44249a9879
--- /dev/null
+++ b/packages/jest-core/tsconfig.json
@@ -0,0 +1,24 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "build"
+  },
+  // TODO: This is missing `@jest/reporters`
+  "references": [
+    {"path": "../jest-changed-files"},
+    {"path": "../jest-config"},
+    {"path": "../jest-haste-map"},
+    {"path": "../jest-message-util"},
+    {"path": "../jest-regex-util"},
+    {"path": "../jest-resolve-dependencies"},
+    {"path": "../jest-runner"},
+    {"path": "../jest-runtime"},
+    {"path": "../jest-snapshot"},
+    {"path": "../jest-types"},
+    {"path": "../jest-transform"},
+    {"path": "../jest-util"},
+    {"path": "../jest-validate"},
+    {"path": "../jest-watcher"}
+  ]
+}
diff --git a/packages/jest-haste-map/src/index.ts b/packages/jest-haste-map/src/index.ts
index e4410350efa9..88a0aa893d00 100644
--- a/packages/jest-haste-map/src/index.ts
+++ b/packages/jest-haste-map/src/index.ts
@@ -31,8 +31,10 @@ import watchmanCrawl from './crawlers/watchman';
 import WatchmanWatcher from './lib/WatchmanWatcher';
 import * as fastPath from './lib/fast_path';
 import {
+  ChangeEvent,
+  EventsQueue,
   FileMetaData,
-  HasteMap as HasteMapObject,
+  HasteMap as InternalHasteMapObject,
   HasteRegExp,
   InternalHasteMap,
   Mapper,
@@ -105,6 +107,8 @@ namespace HasteMap {
   export type ModuleMap = HasteModuleMap;
   export type SerializableModuleMap = HasteSerializableModuleMap;
   export type FS = HasteFS;
+  export type HasteMapObject = InternalHasteMapObject;
+  export type HasteChangeEvent = ChangeEvent;
 }
 
 const CHANGE_INTERVAL = 30;
@@ -226,7 +230,7 @@ const getWhiteList = (list: Array<string> | undefined): RegExp | null => {
  */
 /* eslint-disable-next-line no-redeclare */
 class HasteMap extends EventEmitter {
-  private _buildPromise: Promise<HasteMapObject> | null;
+  private _buildPromise: Promise<InternalHasteMapObject> | null;
   private _cachePath: Config.Path;
   private _changeInterval?: NodeJS.Timeout;
   private _console: Console;
@@ -331,7 +335,7 @@ class HasteMap extends EventEmitter {
     return this._cachePath;
   }
 
-  build(): Promise<HasteMapObject> {
+  build(): Promise<InternalHasteMapObject> {
     if (!this._buildPromise) {
       this._buildPromise = this._buildFileMap()
         .then(data => this._buildHasteMap(data))
@@ -785,11 +789,7 @@ class HasteMap extends EventEmitter {
     const rootDir = this._options.rootDir;
 
     let changeQueue: Promise<null | void> = Promise.resolve();
-    let eventsQueue: Array<{
-      filePath: Config.Path;
-      stat: fs.Stats | undefined;
-      type: string;
-    }> = [];
+    let eventsQueue: EventsQueue = [];
     // We only need to copy the entire haste map once on every "frame".
     let mustCopy = true;
 
@@ -818,7 +818,7 @@ class HasteMap extends EventEmitter {
     const emitChange = () => {
       if (eventsQueue.length) {
         mustCopy = true;
-        this.emit('change', {
+        const changeEvent: ChangeEvent = {
           eventsQueue,
           hasteFS: new HasteFS({
             files: hasteMap.files,
@@ -830,7 +830,8 @@ class HasteMap extends EventEmitter {
             mocks: hasteMap.mocks,
             rootDir,
           }),
-        });
+        };
+        this.emit('change', changeEvent);
         eventsQueue = [];
       }
     };
diff --git a/packages/jest-haste-map/src/types.ts b/packages/jest-haste-map/src/types.ts
index c5e85fc8d9b9..59d2f8022330 100644
--- a/packages/jest-haste-map/src/types.ts
+++ b/packages/jest-haste-map/src/types.ts
@@ -5,6 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+import fs from 'fs';
 import {Config} from '@jest/types';
 import ModuleMap from './ModuleMap';
 import HasteFS from './HasteFS';
@@ -102,3 +103,15 @@ export type HType = {
 };
 
 export type HTypeValue = HType[keyof HType];
+
+export type EventsQueue = Array<{
+  filePath: Config.Path;
+  stat: fs.Stats | undefined;
+  type: string;
+}>;
+
+export type ChangeEvent = {
+  eventsQueue: EventsQueue;
+  hasteFS: HasteFS;
+  moduleMap: ModuleMap;
+};
diff --git a/packages/jest-runner/src/index.ts b/packages/jest-runner/src/index.ts
index e50e94fcf8e3..1fe4c0eee6a8 100644
--- a/packages/jest-runner/src/index.ts
+++ b/packages/jest-runner/src/index.ts
@@ -15,7 +15,7 @@ import {
   OnTestFailure,
   OnTestStart,
   OnTestSuccess,
-  Test,
+  Test as JestTest,
   TestRunnerContext,
   TestRunnerOptions,
   TestWatcher,
@@ -28,6 +28,11 @@ interface WorkerInterface extends Worker {
   worker: typeof worker;
 }
 
+namespace TestRunner {
+  export type Test = JestTest;
+}
+
+/* eslint-disable-next-line no-redeclare */
 class TestRunner {
   private _globalConfig: Config.GlobalConfig;
   private _context: TestRunnerContext;
@@ -38,7 +43,7 @@ class TestRunner {
   }
 
   async runTests(
-    tests: Array<Test>,
+    tests: Array<JestTest>,
     watcher: TestWatcher,
     onStart: OnTestStart,
     onResult: OnTestSuccess,
@@ -57,7 +62,7 @@ class TestRunner {
   }
 
   private async _createInBandTestRun(
-    tests: Array<Test>,
+    tests: Array<JestTest>,
     watcher: TestWatcher,
     onStart: OnTestStart,
     onResult: OnTestSuccess,
@@ -91,7 +96,7 @@ class TestRunner {
   }
 
   private async _createParallelTestRun(
-    tests: Array<Test>,
+    tests: Array<JestTest>,
     watcher: TestWatcher,
     onStart: OnTestStart,
     onResult: OnTestSuccess,
@@ -111,7 +116,7 @@ class TestRunner {
 
     // Send test suites to workers continuously instead of all at once to track
     // the start time of individual tests.
-    const runTestInWorker = (test: Test) =>
+    const runTestInWorker = (test: JestTest) =>
       mutex(async () => {
         if (watcher.isInterrupted()) {
           return Promise.reject();
@@ -130,7 +135,10 @@ class TestRunner {
         });
       });
 
-    const onError = async (err: TestResult.SerializableError, test: Test) => {
+    const onError = async (
+      err: TestResult.SerializableError,
+      test: JestTest,
+    ) => {
       await onFailure(test, err);
       if (err.type === 'ProcessTerminatedError') {
         console.error(
diff --git a/packages/jest-runner/src/types.ts b/packages/jest-runner/src/types.ts
index 86f26d086fa2..78fb71d00d95 100644
--- a/packages/jest-runner/src/types.ts
+++ b/packages/jest-runner/src/types.ts
@@ -26,12 +26,6 @@ export type Context = {
   resolver: HasteResolver;
 };
 
-// TODO: Obtain this from @jest/reporters once its been migrated
-type ReporterOnStartOptions = {
-  estimatedTime: number;
-  showStatus: boolean;
-};
-
 export type OnTestStart = (test: Test) => Promise<void>;
 export type OnTestFailure = (
   test: Test,
@@ -42,24 +36,6 @@ export type OnTestSuccess = (
   testResult: TestResult.TestResult,
 ) => Promise<void>;
 
-export type Reporter = {
-  onTestResult: (
-    test: Test,
-    testResult: TestResult.TestResult,
-    aggregatedResult: TestResult.AggregatedResult,
-  ) => Promise<void>;
-  onRunStart: (
-    results: TestResult.AggregatedResult,
-    options: ReporterOnStartOptions,
-  ) => Promise<void>;
-  onTestStart: (test: Test) => Promise<void>;
-  onRunComplete: (
-    contexts: Set<Context>,
-    results: TestResult.AggregatedResult,
-  ) => Promise<void>;
-  getLastError: () => Error;
-};
-
 export type TestFramework = (
   globalConfig: Config.GlobalConfig,
   config: Config.ProjectConfig,
@@ -76,11 +52,6 @@ export type TestRunnerContext = {
   changedFiles?: Set<Config.Path>;
 };
 
-export type TestRunData = Array<{
-  context: Context;
-  matches: {allTests: number; tests: Array<Test>; total: number};
-}>;
-
 // TODO: Should live in `@jest/core` or `jest-watcher`
 export type WatcherState = {
   interrupted: boolean;
diff --git a/packages/jest-runtime/src/index.ts b/packages/jest-runtime/src/index.ts
index 0cae4501c33b..e6e4fbaae8fa 100644
--- a/packages/jest-runtime/src/index.ts
+++ b/packages/jest-runtime/src/index.ts
@@ -30,7 +30,7 @@ import stripBOM from 'strip-bom';
 import {run as cliRun} from './cli';
 import {options as cliOptions} from './cli/args';
 import {findSiblingsWithFileExtension} from './helpers';
-import {Context} from './types';
+import {Context as JestContext} from './types';
 
 type HasteMapOptions = {
   console?: Console;
@@ -52,6 +52,10 @@ type ResolveOptions = Parameters<typeof require.resolve>[1];
 type BooleanObject = {[key: string]: boolean};
 type CacheFS = {[path: string]: string};
 
+namespace Runtime {
+  export type Context = JestContext;
+}
+
 const testTimeoutSymbol = Symbol.for('TEST_TIMEOUT_SYMBOL');
 const retryTimesSymbol = Symbol.for('RETRY_TIMES');
 
@@ -72,6 +76,7 @@ const getModuleNameMapper = (config: Config.ProjectConfig) => {
 
 const unmockRegExpCache = new WeakMap();
 
+/* eslint-disable-next-line no-redeclare */
 class Runtime {
   static ScriptTransformer: typeof ScriptTransformer;
 
@@ -188,7 +193,7 @@ class Runtime {
       watch?: boolean;
       watchman: boolean;
     },
-  ): Promise<Context> {
+  ): Promise<JestContext> {
     createDirectory(config.cacheDirectory);
     const instance = Runtime.createHasteMap(config, {
       console: options.console,
diff --git a/packages/jest-transform/src/ScriptTransformer.ts b/packages/jest-transform/src/ScriptTransformer.ts
index 2fbf03a78ecf..b8d0c5507b2e 100644
--- a/packages/jest-transform/src/ScriptTransformer.ts
+++ b/packages/jest-transform/src/ScriptTransformer.ts
@@ -223,7 +223,7 @@ export default class ScriptTransformer {
     // Ignore cache if `config.cache` is set (--no-cache)
     let code = this._config.cache ? readCodeCacheFile(cacheFilePath) : null;
 
-    const shouldCallTransform = transform && this._shouldTransform(filename);
+    const shouldCallTransform = transform && this.shouldTransform(filename);
 
     // That means that the transform has a custom instrumentation
     // logic and will handle it based on `config.collectCoverage` option
@@ -322,7 +322,7 @@ export default class ScriptTransformer {
     const willTransform =
       !isInternalModule &&
       !isCoreModule &&
-      (this._shouldTransform(filename) || instrument);
+      (this.shouldTransform(filename) || instrument);
 
     try {
       const extraGlobals = (options && options.extraGlobals) || [];
@@ -399,7 +399,15 @@ export default class ScriptTransformer {
     return result;
   }
 
+  /**
+   * @deprecated use `this.shouldTransform` instead
+   */
+  // @ts-ignore: Unused and private - remove in Jest 25
   private _shouldTransform(filename: Config.Path): boolean {
+    return this.shouldTransform(filename);
+  }
+
+  shouldTransform(filename: Config.Path): boolean {
     const ignoreRegexp = this._cache.ignorePatternsRegExp;
     const isIgnored = ignoreRegexp ? ignoreRegexp.test(filename) : false;
 
diff --git a/packages/jest-types/src/Config.ts b/packages/jest-types/src/Config.ts
index bdd9c64efc39..c2c70c829be9 100644
--- a/packages/jest-types/src/Config.ts
+++ b/packages/jest-types/src/Config.ts
@@ -19,7 +19,7 @@ export type HasteConfig = {
   providesModuleNodeModules: Array<string>;
 };
 
-export type ReporterConfig = [string, Object];
+export type ReporterConfig = [string, {[key: string]: unknown}];
 
 export type ConfigGlobals = Object;
 
diff --git a/packages/jest-watcher/src/BaseWatchPlugin.ts b/packages/jest-watcher/src/BaseWatchPlugin.ts
index 3570559bcab7..2e7386ae3f8c 100644
--- a/packages/jest-watcher/src/BaseWatchPlugin.ts
+++ b/packages/jest-watcher/src/BaseWatchPlugin.ts
@@ -5,32 +5,41 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {WatchPlugin} from './types';
+import {Config} from '@jest/types';
+import {
+  JestHookSubscriber,
+  UpdateConfigCallback,
+  UsageData,
+  WatchPlugin,
+} from './types';
 
 class BaseWatchPlugin implements WatchPlugin {
-  protected _stdin: NodeJS.ReadableStream;
-  protected _stdout: NodeJS.WritableStream;
+  protected _stdin: NodeJS.ReadStream;
+  protected _stdout: NodeJS.WriteStream;
 
   constructor({
     stdin,
     stdout,
   }: {
-    stdin: NodeJS.ReadableStream;
-    stdout: NodeJS.WritableStream;
+    stdin: NodeJS.ReadStream;
+    stdout: NodeJS.WriteStream;
   }) {
     this._stdin = stdin;
     this._stdout = stdout;
   }
 
-  apply() {}
+  apply(_hooks: JestHookSubscriber) {}
 
-  getUsageInfo() {
+  getUsageInfo(_globalConfig: Config.GlobalConfig): UsageData | null {
     return null;
   }
 
-  onKey() {}
+  onKey(_key: string) {}
 
-  run() {
+  run(
+    _globalConfig: Config.GlobalConfig,
+    _updateConfigAndRun: UpdateConfigCallback,
+  ): Promise<void | boolean> {
     return Promise.resolve();
   }
 }
diff --git a/packages/jest-watcher/src/PatternPrompt.ts b/packages/jest-watcher/src/PatternPrompt.ts
index 8663932f2b69..2490d9943e16 100644
--- a/packages/jest-watcher/src/PatternPrompt.ts
+++ b/packages/jest-watcher/src/PatternPrompt.ts
@@ -9,6 +9,7 @@ import chalk from 'chalk';
 import ansiEscapes from 'ansi-escapes';
 import {specialChars} from 'jest-util';
 import Prompt from './lib/Prompt';
+import {ScrollOptions} from './types';
 
 const {CLEAR} = specialChars;
 
@@ -35,7 +36,11 @@ export default class PatternPrompt {
     this._currentUsageRows = usageRows;
   }
 
-  run(onSuccess: () => void, onCancel: () => void, options?: {header: string}) {
+  run(
+    onSuccess: (value: string) => void,
+    onCancel: () => void,
+    options?: {header: string},
+  ) {
     this._pipe.write(ansiEscapes.cursorHide);
     this._pipe.write(CLEAR);
 
@@ -52,7 +57,7 @@ export default class PatternPrompt {
     this._prompt.enter(this._onChange.bind(this), onSuccess, onCancel);
   }
 
-  protected _onChange() {
+  protected _onChange(_pattern: string, _options: ScrollOptions) {
     this._pipe.write(ansiEscapes.eraseLine);
     this._pipe.write(ansiEscapes.cursorLeft);
   }
diff --git a/packages/jest-watcher/src/index.ts b/packages/jest-watcher/src/index.ts
index 766fba239f10..1ccf49f523e9 100644
--- a/packages/jest-watcher/src/index.ts
+++ b/packages/jest-watcher/src/index.ts
@@ -9,5 +9,15 @@ export {default as BaseWatchPlugin} from './BaseWatchPlugin';
 export {default as JestHook} from './JestHooks';
 export {default as PatternPrompt} from './PatternPrompt';
 export * from './constants';
+export {
+  AllowedConfigOptions,
+  JestHookEmitter,
+  JestHookSubscriber,
+  ScrollOptions,
+  UpdateConfigCallback,
+  UsageData,
+  WatchPlugin,
+  WatchPluginClass,
+} from './types';
 export {default as Prompt} from './lib/Prompt';
 export * from './lib/patternModeHelpers';
diff --git a/packages/jest-watcher/src/lib/Prompt.ts b/packages/jest-watcher/src/lib/Prompt.ts
index c3e26c233e87..46612eb60302 100644
--- a/packages/jest-watcher/src/lib/Prompt.ts
+++ b/packages/jest-watcher/src/lib/Prompt.ts
@@ -12,8 +12,8 @@ export default class Prompt {
   private _entering: boolean;
   private _value: string;
   private _onChange: () => void;
-  private _onSuccess: (value?: string) => void;
-  private _onCancel: (value?: string) => void;
+  private _onSuccess: (value: string) => void;
+  private _onCancel: (value: string) => void;
   private _offset: number;
   private _promptLength: number;
   private _selection: string | null;
@@ -39,7 +39,7 @@ export default class Prompt {
 
   enter(
     onChange: (pattern: string, options: ScrollOptions) => void,
-    onSuccess: () => void,
+    onSuccess: (pattern: string) => void,
     onCancel: () => void,
   ) {
     this._entering = true;
diff --git a/packages/jest-watcher/src/types.ts b/packages/jest-watcher/src/types.ts
index 8886c011cd1f..e8c5bb128d20 100644
--- a/packages/jest-watcher/src/types.ts
+++ b/packages/jest-watcher/src/types.ts
@@ -64,18 +64,24 @@ export type AllowedConfigOptions = Partial<
   > & {mode: 'watch' | 'watchAll'}
 >;
 
+export type UpdateConfigCallback = (config?: AllowedConfigOptions) => void;
+
 export interface WatchPlugin {
   isInternal?: boolean;
   apply?: (hooks: JestHookSubscriber) => void;
-  getUsageInfo?: (
-    globalConfig: Config.GlobalConfig,
-  ) => UsageData | undefined | null;
+  getUsageInfo?: (globalConfig: Config.GlobalConfig) => UsageData | null;
   onKey?: (value: string) => void;
   run?: (
     globalConfig: Config.GlobalConfig,
-    updateConfigAndRun: (config?: AllowedConfigOptions) => void,
+    updateConfigAndRun: UpdateConfigCallback,
   ) => Promise<void | boolean>;
 }
+export interface WatchPluginClass {
+  new (options: {
+    stdin: NodeJS.ReadStream;
+    stdout: NodeJS.WriteStream;
+  }): WatchPlugin;
+}
 
 export type ScrollOptions = {
   offset: number;
diff --git a/website/versioned_docs/version-23.x/WatchPlugins.md b/website/versioned_docs/version-23.x/WatchPlugins.md
index 6f830989149c..56a2208d2e59 100644
--- a/website/versioned_docs/version-23.x/WatchPlugins.md
+++ b/website/versioned_docs/version-23.x/WatchPlugins.md
@@ -165,6 +165,7 @@ For stability and safety reasons, only part of the global configuration keys can
 - [`notify`](configuration.html#notify-boolean)
 - [`notifyMode`](configuration.html#notifymode-string)
 - [`onlyFailures`](configuration.html#onlyfailures-boolean)
+- [`passWithNoTests`](cli.html#passwithnotests)
 - [`reporters`](configuration.html#reporters-array-modulename-modulename-options)
 - [`testNamePattern`](cli.html#testnamepattern-regex)
 - [`testPathPattern`](cli.html#testpathpattern-regex)
diff --git a/yarn.lock b/yarn.lock
index ea115684f057..d7670b5c202f 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -10102,7 +10102,7 @@ pinkie@^2.0.0:
   resolved "https://registry.yarnpkg.com/pinkie/-/pinkie-2.0.4.tgz#72556b80cfa0d48a974e80e77248e80ed4f7f870"
   integrity sha1-clVrgM+g1IqXToDnckjoDtT3+HA=
 
-pirates@^4.0.0:
+pirates@^4.0.0, pirates@^4.0.1:
   version "4.0.1"
   resolved "https://registry.yarnpkg.com/pirates/-/pirates-4.0.1.tgz#643a92caf894566f91b2b986d2c66950a8e2fb87"
   integrity sha512-WuNqLTbMI3tmfef2TKxlQmAiLHKtFhlsCZnPIpuv2Ow0RDVO8lfy1Opf4NUzlMXLjPl+Men7AuVdX6TA+s+uGA==