diff --git a/CHANGELOG.md b/CHANGELOG.md
index d7c85530b170..d0a22f26256c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,8 @@
 - `[expect]`: Improve report when matcher fails, part 10 ([#7960](https://github.com/facebook/jest/pull/7960))
 - `[pretty-format]` Support `React.memo` ([#7891](https://github.com/facebook/jest/pull/7891))
 - `[jest-config]` Print error information on preset normalization error ([#7935](https://github.com/facebook/jest/pull/7935))
+- `[jest-haste-map]` Add `skipPackageJson` option ([#7778](https://github.com/facebook/jest/pull/7778))
+- `[jest-get-type]` Add `isPrimitive` function ([#7708](https://github.com/facebook/jest/pull/7708))
 
 ### Fixes
 
@@ -22,10 +24,14 @@
 - `[jest-transform]` Normalize config and remove unecessary checks, convert `TestUtils.js` to TypeScript ([#7801](https://github.com/facebook/jest/pull/7801))
 - `[jest-worker]` Fix `jest-worker` when using pre-allocated jobs ([#7934](https://github.com/facebook/jest/pull/7934))
 - `[jest-changed-files]` Fix `getChangedFilesFromRoots` to not return parts of the commit messages as if they were files, when the commit messages contained multiple paragraphs ([#7961](https://github.com/facebook/jest/pull/7961))
+- `[jest-haste-map]` Enforce uniqueness in names (mocks and haste ids) ([#8002](https://github.com/facebook/jest/pull/8002))
 - `[static]` Remove console log '-' on the front page
+- `[jest-jasmine2]`: Throw explicit error when errors happen after test is considered complete ([#8005](https://github.com/facebook/jest/pull/8005))
+- `[jest-circus]`: Throw explicit error when errors happen after test is considered complete ([#8005](https://github.com/facebook/jest/pull/8005))
 
 ### Chore & Maintenance
 
+- `[jest-environment-jsdom]`: Migrate to TypeScript ([#7985](https://github.com/facebook/jest/pull/8003))
 - `[jest-environment-node]`: Migrate to TypeScript ([#7985](https://github.com/facebook/jest/pull/7985))
 - `[*]`: Setup building, linting and testing of TypeScript ([#7808](https://github.com/facebook/jest/pull/7808), [#7855](https://github.com/facebook/jest/pull/7855), [#7951](https://github.com/facebook/jest/pull/7951))
 - `[pretty-format]`: Migrate to TypeScript ([#7809](https://github.com/facebook/jest/pull/7809), [#7809](https://github.com/facebook/jest/pull/7972))
@@ -62,6 +68,7 @@
 - `[jest-runner]`: Migrate to TypeScript ([#7968](https://github.com/facebook/jest/pull/7968))
 - `[jest-runtime]`: Migrate to TypeScript ([#7964](https://github.com/facebook/jest/pull/7964), [#7988](https://github.com/facebook/jest/pull/7988))
 - `[@jest/fake-timers]`: Extract FakeTimers class from `jest-util` into a new separate package ([#7987](https://github.com/facebook/jest/pull/7987))
+- `[jest-repl]`: Migrate to TypeScript ([#8000](https://github.com/facebook/jest/pull/8000))
 - `[@jest/core]`: Migrate to TypeScript ([#7998](https://github.com/facebook/jest/pull/7998))
 
 ### Performance
@@ -93,6 +100,7 @@
 - `[jest-runtime]` Exclude setup/teardown files from coverage report ([#7790](https://github.com/facebook/jest/pull/7790)
 - `[babel-jest]` Throw an error if `babel-jest` tries to transform a file ignored by Babel ([#7797](https://github.com/facebook/jest/pull/7797))
 - `[babel-plugin-jest-hoist]` Ignore TS type references when looking for out-of-scope references ([#7799](https://github.com/facebook/jest/pull/7799)
+- `[expect]` fixed asymmetrical equality of cyclic objects ([#7730](https://github.com/facebook/jest/pull/7730))
 
 ### Chore & Maintenance
 
diff --git a/e2e/__tests__/detectOpenHandles.ts b/e2e/__tests__/detectOpenHandles.ts
index f6b4503e980f..70420b49e21d 100644
--- a/e2e/__tests__/detectOpenHandles.ts
+++ b/e2e/__tests__/detectOpenHandles.ts
@@ -22,7 +22,7 @@ try {
   }
 }
 
-function getTextAfterTest(stderr) {
+function getTextAfterTest(stderr: string) {
   return (stderr.split(/Ran all test suites(.*)\n/)[2] || '').trim();
 }
 
diff --git a/e2e/__tests__/failures.test.ts b/e2e/__tests__/failures.test.ts
index f99bed6a4938..851bb3d1a39b 100644
--- a/e2e/__tests__/failures.test.ts
+++ b/e2e/__tests__/failures.test.ts
@@ -12,9 +12,9 @@ import runJest from '../runJest';
 
 const dir = path.resolve(__dirname, '../failures');
 
-const normalizeDots = text => text.replace(/\.{1,}$/gm, '.');
+const normalizeDots = (text: string) => text.replace(/\.{1,}$/gm, '.');
 
-function cleanStderr(stderr) {
+function cleanStderr(stderr: string) {
   const {rest} = extractSummary(stderr);
   return rest
     .replace(/.*(jest-jasmine2|jest-circus).*\n/g, '')
@@ -182,3 +182,12 @@ test('works with named snapshot failures', () => {
     wrap(result.substring(0, result.indexOf('Snapshot Summary'))),
   ).toMatchSnapshot();
 });
+
+test('errors after test has completed', () => {
+  const {stderr} = runJest(dir, ['errorAfterTestComplete.test.js']);
+
+  expect(stderr).toMatch(
+    /Error: Caught error after test environment was torn down/,
+  );
+  expect(stderr).toMatch(/Failed: "fail async"/);
+});
diff --git a/e2e/failures/__tests__/errorAfterTestComplete.test.js b/e2e/failures/__tests__/errorAfterTestComplete.test.js
new file mode 100644
index 000000000000..6bfb7dc3ae79
--- /dev/null
+++ b/e2e/failures/__tests__/errorAfterTestComplete.test.js
@@ -0,0 +1,14 @@
+/**
+ * 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.
+ *
+ * @emails oncall+jsinfra
+ */
+'use strict';
+
+test('a failing test', done => {
+  setTimeout(() => done('fail async'), 5);
+  done();
+});
diff --git a/packages/expect/src/__tests__/matchers.test.js b/packages/expect/src/__tests__/matchers.test.js
index 4e2cf535b6b3..cff90804df79 100644
--- a/packages/expect/src/__tests__/matchers.test.js
+++ b/packages/expect/src/__tests__/matchers.test.js
@@ -606,6 +606,59 @@ describe('.toEqual()', () => {
     });
     expect(actual).toEqual({x: 3});
   });
+
+  describe('cyclic object equality', () => {
+    test('properties with the same circularity are equal', () => {
+      const a = {};
+      a.x = a;
+      const b = {};
+      b.x = b;
+      expect(a).toEqual(b);
+      expect(b).toEqual(a);
+
+      const c = {};
+      c.x = a;
+      const d = {};
+      d.x = b;
+      expect(c).toEqual(d);
+      expect(d).toEqual(c);
+    });
+
+    test('properties with different circularity are not equal', () => {
+      const a = {};
+      a.x = {y: a};
+      const b = {};
+      const bx = {};
+      b.x = bx;
+      bx.y = bx;
+      expect(a).not.toEqual(b);
+      expect(b).not.toEqual(a);
+
+      const c = {};
+      c.x = a;
+      const d = {};
+      d.x = b;
+      expect(c).not.toEqual(d);
+      expect(d).not.toEqual(c);
+    });
+
+    test('are not equal if circularity is not on the same property', () => {
+      const a = {};
+      const b = {};
+      a.a = a;
+      b.a = {};
+      b.a.a = a;
+      expect(a).not.toEqual(b);
+      expect(b).not.toEqual(a);
+
+      const c = {};
+      c.x = {x: c};
+      const d = {};
+      d.x = d;
+      expect(c).not.toEqual(d);
+      expect(d).not.toEqual(c);
+    });
+  });
 });
 
 describe('.toBeInstanceOf()', () => {
diff --git a/packages/expect/src/jasmineUtils.ts b/packages/expect/src/jasmineUtils.ts
index 11e368d11001..f16bc5aeaa64 100644
--- a/packages/expect/src/jasmineUtils.ts
+++ b/packages/expect/src/jasmineUtils.ts
@@ -64,9 +64,9 @@ function asymmetricMatch(a: any, b: any) {
 function eq(
   a: any,
   b: any,
-  aStack: any,
-  bStack: any,
-  customTesters: any,
+  aStack: Array<unknown>,
+  bStack: Array<unknown>,
+  customTesters: Array<Tester>,
   hasKey: any,
 ): boolean {
   var result = true;
@@ -149,14 +149,17 @@ function eq(
     return false;
   }
 
-  // Assume equality for cyclic structures. The algorithm for detecting cyclic
-  // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`.
+  // Used to detect circular references.
   var length = aStack.length;
   while (length--) {
     // Linear search. Performance is inversely proportional to the number of
     // unique nested structures.
-    if (aStack[length] == a) {
-      return bStack[length] == b;
+    // circular references at same depth are equal
+    // circular reference is not equal to non-circular one
+    if (aStack[length] === a) {
+      return bStack[length] === b;
+    } else if (bStack[length] === b) {
+      return false;
     }
   }
   // Add the first object to the stack of traversed objects.
diff --git a/packages/jest-circus/src/utils.ts b/packages/jest-circus/src/utils.ts
index 7917d1356e9d..fbad7a725c77 100644
--- a/packages/jest-circus/src/utils.ts
+++ b/packages/jest-circus/src/utils.ts
@@ -153,12 +153,17 @@ const _makeTimeoutMessage = (timeout: number, isHook: boolean) =>
 // the original values in the variables before we require any files.
 const {setTimeout, clearTimeout} = global;
 
+function checkIsError(error: any): error is Error {
+  return !!(error && (error as Error).message && (error as Error).stack);
+}
+
 export const callAsyncCircusFn = (
   fn: AsyncFn,
   testContext: TestContext | undefined,
   {isHook, timeout}: {isHook?: boolean | null; timeout: number},
 ): Promise<any> => {
   let timeoutID: NodeJS.Timeout;
+  let completed = false;
 
   return new Promise((resolve, reject) => {
     timeoutID = setTimeout(
@@ -170,15 +175,20 @@ export const callAsyncCircusFn = (
     // soon as `done` called.
     if (fn.length) {
       const done = (reason?: Error | string): void => {
-        const isError =
-          reason && (reason as Error).message && (reason as Error).stack;
-        return reason
-          ? reject(
-              isError
-                ? reason
-                : new Error(`Failed: ${prettyFormat(reason, {maxDepth: 3})}`),
-            )
-          : resolve();
+        const errorAsErrorObject = checkIsError(reason)
+          ? reason
+          : new Error(`Failed: ${prettyFormat(reason, {maxDepth: 3})}`);
+
+        // Consider always throwing, regardless if `reason` is set or not
+        if (completed && reason) {
+          errorAsErrorObject.message =
+            'Caught error after test environment was torn down\n\n' +
+            errorAsErrorObject.message;
+
+          throw errorAsErrorObject;
+        }
+
+        return reason ? reject(errorAsErrorObject) : resolve();
       };
 
       return fn.call(testContext, done);
@@ -221,12 +231,14 @@ export const callAsyncCircusFn = (
     return resolve();
   })
     .then(() => {
+      completed = true;
       // If timeout is not cleared/unrefed the node process won't exit until
       // it's resolved.
       timeoutID.unref && timeoutID.unref();
       clearTimeout(timeoutID);
     })
     .catch(error => {
+      completed = true;
       timeoutID.unref && timeoutID.unref();
       clearTimeout(timeoutID);
       throw error;
diff --git a/packages/jest-config/tsconfig.json b/packages/jest-config/tsconfig.json
index 55f2ed3ff353..16502ade2786 100644
--- a/packages/jest-config/tsconfig.json
+++ b/packages/jest-config/tsconfig.json
@@ -4,10 +4,10 @@
     "rootDir": "src",
     "outDir": "build"
   },
-  // TODO: This is missing `jest-validate`, in addition to
-  // `jest-environment-jsdom` and `jest-jasmine2`, but those are just
-  // `require.resolve`d, so no real use for their types
+  // TODO: This is missing `jest-validate`, in addition to and `jest-jasmine2`,
+  // but those are just `require.resolve`d, so no real use for their types
   "references": [
+    {"path": "../jest-environment-jsdom"},
     {"path": "../jest-environment-node"},
     {"path": "../jest-get-type"},
     {"path": "../jest-regex-util"},
diff --git a/packages/jest-each/src/bind.js b/packages/jest-each/src/bind.js
index b09a0dff20f3..8b8d95aa4f54 100644
--- a/packages/jest-each/src/bind.js
+++ b/packages/jest-each/src/bind.js
@@ -10,7 +10,7 @@
 import util from 'util';
 import chalk from 'chalk';
 import pretty from 'pretty-format';
-import getType from 'jest-get-type';
+import {isPrimitive} from 'jest-get-type';
 import {ErrorWithStack} from 'jest-util';
 
 type Table = Array<Array<any>>;
@@ -24,13 +24,6 @@ const RECEIVED_COLOR = chalk.red;
 const SUPPORTED_PLACEHOLDERS = /%[sdifjoOp%]/g;
 const PRETTY_PLACEHOLDER = '%p';
 const INDEX_PLACEHOLDER = '%#';
-const PRIMITIVES = new Set([
-  'string',
-  'number',
-  'boolean',
-  'null',
-  'undefined',
-]);
 
 export default (cb: Function, supportsDone: boolean = true) => (...args: any) =>
   function eachBind(title: string, test: Function, timeout: number): void {
@@ -203,10 +196,9 @@ const getMatchingKeyPaths = title => (matches, key) =>
 const replaceKeyPathWithValue = data => (title, match) => {
   const keyPath = match.replace('$', '').split('.');
   const value = getPath(data, keyPath);
-  const valueType = getType(value);
 
-  if (PRIMITIVES.has(valueType)) {
-    return title.replace(match, value);
+  if (isPrimitive(value)) {
+    return title.replace(match, String(value));
   }
   return title.replace(match, pretty(value, {maxDepth: 1, min: true}));
 };
diff --git a/packages/jest-environment-jsdom/package.json b/packages/jest-environment-jsdom/package.json
index 65799a5f7909..25c3d65c6a04 100644
--- a/packages/jest-environment-jsdom/package.json
+++ b/packages/jest-environment-jsdom/package.json
@@ -8,13 +8,16 @@
   },
   "license": "MIT",
   "main": "build/index.js",
+  "types": "build/index.d.ts",
   "dependencies": {
+    "@jest/environment": "^24.1.0",
     "@jest/fake-timers": "^24.1.0",
+    "@jest/types": "^24.1.0",
     "jest-mock": "^24.0.0",
     "jest-util": "^24.0.0",
     "jsdom": "^11.5.1"
   },
-  "devDependencies":  {
+  "devDependencies": {
     "@types/jsdom": "^11.12.0"
   },
   "engines": {
diff --git a/packages/jest-environment-jsdom/src/__mocks__/index.js b/packages/jest-environment-jsdom/src/__mocks__/index.ts
similarity index 81%
rename from packages/jest-environment-jsdom/src/__mocks__/index.js
rename to packages/jest-environment-jsdom/src/__mocks__/index.ts
index f2bf9a30476e..b528bc840c64 100644
--- a/packages/jest-environment-jsdom/src/__mocks__/index.js
+++ b/packages/jest-environment-jsdom/src/__mocks__/index.ts
@@ -8,9 +8,10 @@
 
 const vm = jest.requireActual('vm');
 
-const JSDOMEnvironment = jest.genMockFromModule('../index');
+const JSDOMEnvironment = jest.genMockFromModule('../index') as jest.Mock;
 
 JSDOMEnvironment.mockImplementation(function(config) {
+  // @ts-ignore
   this.global = {
     JSON,
     console: {},
@@ -18,14 +19,16 @@ JSDOMEnvironment.mockImplementation(function(config) {
 
   const globalValues = {...config.globals};
   for (const customGlobalKey in globalValues) {
+    // @ts-ignore
     this.global[customGlobalKey] = globalValues[customGlobalKey];
   }
 });
 
 JSDOMEnvironment.prototype.runSourceText.mockImplementation(function(
-  sourceText,
-  filename,
+  sourceText: string,
+  filename: string,
 ) {
+  // @ts-ignore
   return vm.runInNewContext(sourceText, this.global, {
     displayErrors: false,
     filename,
diff --git a/packages/jest-environment-jsdom/src/__tests__/jsdom_environment.test.js b/packages/jest-environment-jsdom/src/__tests__/jsdom_environment.test.ts
similarity index 100%
rename from packages/jest-environment-jsdom/src/__tests__/jsdom_environment.test.js
rename to packages/jest-environment-jsdom/src/__tests__/jsdom_environment.test.ts
diff --git a/packages/jest-environment-jsdom/src/index.js b/packages/jest-environment-jsdom/src/index.ts
similarity index 55%
rename from packages/jest-environment-jsdom/src/index.js
rename to packages/jest-environment-jsdom/src/index.ts
index 56f417ba8188..8d0c33c1df7c 100644
--- a/packages/jest-environment-jsdom/src/index.js
+++ b/packages/jest-environment-jsdom/src/index.ts
@@ -3,28 +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 {Script} from 'vm';
-import type {ProjectConfig} from 'types/Config';
-import type {EnvironmentContext} from 'types/Environment';
-import type {Global} from 'types/Global';
-import type {ModuleMocker} from 'jest-mock';
-
-import {JestFakeTimers as FakeTimers} from '@jest/fake-timers';
+import {Script} from 'vm';
+import {Global, Config} from '@jest/types';
 import {installCommonGlobals} from 'jest-util';
-import mock from 'jest-mock';
+import mock, {ModuleMocker} from 'jest-mock';
+import {JestFakeTimers as FakeTimers} from '@jest/fake-timers';
+import {JestEnvironment, EnvironmentContext} from '@jest/environment';
 import {JSDOM, VirtualConsole} from 'jsdom';
 
-class JSDOMEnvironment {
-  dom: ?Object;
-  fakeTimers: ?FakeTimers<number>;
-  global: ?Global;
-  errorEventListener: ?Function;
-  moduleMocker: ?ModuleMocker;
+// The `Window` interface does not have an `Error.stackTraceLimit` property, but
+// `JSDOMEnvironment` assumes it is there.
+interface Win extends Window {
+  Error: {
+    stackTraceLimit: number;
+  };
+}
+
+function isWin(globals: Win | Global.Global): globals is Win {
+  return (globals as Win).document !== undefined;
+}
+
+// A lot of the globals expected by other APIs are `NodeJS.Global` and not
+// `Window`, so we need to cast here and there
+
+class JSDOMEnvironment implements JestEnvironment {
+  dom: JSDOM | null;
+  fakeTimers: FakeTimers<number> | null;
+  // @ts-ignore
+  global: Global.Global | Win | null;
+  errorEventListener: ((event: Event & {error: Error}) => void) | null;
+  moduleMocker: ModuleMocker | null;
 
-  constructor(config: ProjectConfig, options?: EnvironmentContext = {}) {
+  constructor(config: Config.ProjectConfig, options: EnvironmentContext = {}) {
     this.dom = new JSDOM('<!DOCTYPE html>', {
       pretendToBeVisual: true,
       runScripts: 'dangerously',
@@ -32,11 +44,16 @@ class JSDOMEnvironment {
       virtualConsole: new VirtualConsole().sendTo(options.console || console),
       ...config.testEnvironmentOptions,
     });
-    const global = (this.global = this.dom.window.document.defaultView);
+    const global = (this.global = this.dom.window.document.defaultView as Win);
+
+    if (!global) {
+      throw new Error('JSDOM did not return a Window object');
+    }
+
     // Node's error-message stack size is limited at 10, but it's pretty useful
     // to see more than that when a test fails.
     this.global.Error.stackTraceLimit = 100;
-    installCommonGlobals(global, config.globals);
+    installCommonGlobals(global as any, config.globals);
 
     // Report uncaught errors.
     this.errorEventListener = event => {
@@ -51,20 +68,24 @@ class JSDOMEnvironment {
     const originalAddListener = global.addEventListener;
     const originalRemoveListener = global.removeEventListener;
     let userErrorListenerCount = 0;
-    global.addEventListener = function(name) {
-      if (name === 'error') {
+    global.addEventListener = function(
+      ...args: Parameters<typeof originalAddListener>
+    ) {
+      if (args[0] === 'error') {
         userErrorListenerCount++;
       }
-      return originalAddListener.apply(this, arguments);
+      return originalAddListener.apply(this, args);
     };
-    global.removeEventListener = function(name) {
-      if (name === 'error') {
+    global.removeEventListener = function(
+      ...args: Parameters<typeof originalRemoveListener>
+    ) {
+      if (args[0] === 'error') {
         userErrorListenerCount--;
       }
-      return originalRemoveListener.apply(this, arguments);
+      return originalRemoveListener.apply(this, args);
     };
 
-    this.moduleMocker = new mock.ModuleMocker(global);
+    this.moduleMocker = new mock.ModuleMocker(global as any);
 
     const timerConfig = {
       idToRef: (id: number) => id,
@@ -73,27 +94,29 @@ class JSDOMEnvironment {
 
     this.fakeTimers = new FakeTimers({
       config,
-      global,
+      global: global as any,
       moduleMocker: this.moduleMocker,
       timerConfig,
     });
   }
 
-  setup(): Promise<void> {
+  setup() {
     return Promise.resolve();
   }
 
-  teardown(): Promise<void> {
+  teardown() {
     if (this.fakeTimers) {
       this.fakeTimers.dispose();
     }
     if (this.global) {
-      if (this.errorEventListener) {
+      if (this.errorEventListener && isWin(this.global)) {
         this.global.removeEventListener('error', this.errorEventListener);
       }
       // Dispose "document" to prevent "load" event from triggering.
       Object.defineProperty(this.global, 'document', {value: null});
-      this.global.close();
+      if (isWin(this.global)) {
+        this.global.close();
+      }
     }
     this.errorEventListener = null;
     this.global = null;
@@ -102,12 +125,12 @@ class JSDOMEnvironment {
     return Promise.resolve();
   }
 
-  runScript(script: Script): ?any {
+  runScript(script: Script) {
     if (this.dom) {
-      return this.dom.runVMScript(script);
+      return this.dom.runVMScript(script) as any;
     }
     return null;
   }
 }
 
-module.exports = JSDOMEnvironment;
+export = JSDOMEnvironment;
diff --git a/packages/jest-environment-jsdom/tsconfig.json b/packages/jest-environment-jsdom/tsconfig.json
new file mode 100644
index 000000000000..655d8c8aab7c
--- /dev/null
+++ b/packages/jest-environment-jsdom/tsconfig.json
@@ -0,0 +1,14 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "outDir": "build",
+    "rootDir": "src"
+  },
+  "references": [
+    {"path": "../jest-environment"},
+    {"path": "../jest-fake-timers"},
+    {"path": "../jest-mock"},
+    {"path": "../jest-types"},
+    {"path": "../jest-util"}
+  ]
+}
diff --git a/packages/jest-get-type/src/__tests__/index.test.ts b/packages/jest-get-type/src/__tests__/getType.test.ts
similarity index 97%
rename from packages/jest-get-type/src/__tests__/index.test.ts
rename to packages/jest-get-type/src/__tests__/getType.test.ts
index 8a34a0cb947d..de4bec59d8db 100644
--- a/packages/jest-get-type/src/__tests__/index.test.ts
+++ b/packages/jest-get-type/src/__tests__/getType.test.ts
@@ -6,7 +6,7 @@
  *
  */
 
-import getType from '..';
+import getType from '../';
 
 describe('.getType()', () => {
   test('null', () => expect(getType(null)).toBe('null'));
diff --git a/packages/jest-get-type/src/__tests__/isPrimitive.test.ts b/packages/jest-get-type/src/__tests__/isPrimitive.test.ts
new file mode 100644
index 000000000000..d3e9a7175af5
--- /dev/null
+++ b/packages/jest-get-type/src/__tests__/isPrimitive.test.ts
@@ -0,0 +1,25 @@
+/**
+ * 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 {isPrimitive} from '..';
+
+describe('.isPrimitive()', () => {
+  test.each([null, undefined, 100, 'hello world', true, Symbol.for('a')])(
+    'returns true when given primitive value of: %s',
+    primitive => {
+      expect(isPrimitive(primitive)).toBe(true);
+    },
+  );
+
+  test.each([{}, [], () => {}, /abc/, new Map(), new Set(), new Date()])(
+    'returns false when given non primitive value of: %s',
+    value => {
+      expect(isPrimitive(value)).toBe(false);
+    },
+  );
+});
diff --git a/packages/jest-get-type/src/index.ts b/packages/jest-get-type/src/index.ts
index dd15b71be771..cfea04eaf48a 100644
--- a/packages/jest-get-type/src/index.ts
+++ b/packages/jest-get-type/src/index.ts
@@ -20,9 +20,18 @@ type ValueType =
   | 'symbol'
   | 'undefined';
 
+const PRIMITIVES = new Set<ValueType>([
+  'string',
+  'number',
+  'boolean',
+  'null',
+  'undefined',
+  'symbol',
+]);
+
 // get the type of a value with handling the edge cases like `typeof []`
 // and `typeof null`
-const getType = (value: unknown): ValueType => {
+function getType(value: unknown): ValueType {
   if (value === undefined) {
     return 'undefined';
   } else if (value === null) {
@@ -55,6 +64,8 @@ const getType = (value: unknown): ValueType => {
   }
 
   throw new Error(`value of unknown type: ${value}`);
-};
+}
+
+getType.isPrimitive = (value: unknown) => PRIMITIVES.has(getType(value));
 
 export = getType;
diff --git a/packages/jest-haste-map/src/__tests__/__snapshots__/index.test.js.snap b/packages/jest-haste-map/src/__tests__/__snapshots__/index.test.js.snap
index d86bc28499f3..82841ac1ed01 100644
--- a/packages/jest-haste-map/src/__tests__/__snapshots__/index.test.js.snap
+++ b/packages/jest-haste-map/src/__tests__/__snapshots__/index.test.js.snap
@@ -16,13 +16,7 @@ exports[`HasteMap file system changes processing recovery from duplicate module
 "
 `;
 
-exports[`HasteMap throws on duplicate module ids if "throwOnModuleCollision" is set to true 1`] = `
-[Error: jest-haste-map: Haste module naming collision:
-  Duplicate module name: Strawberry
-  Paths: /project/fruits/another/Strawberry.js collides with /project/fruits/Strawberry.js
-
-This error is caused by \`hasteImpl\` returning the same name for different files.]
-`;
+exports[`HasteMap throws on duplicate module ids if "throwOnModuleCollision" is set to true 1`] = `[Error: Duplicated files or mocks. Please check the console for more info]`;
 
 exports[`HasteMap tries to crawl using node as a fallback 1`] = `
 "jest-haste-map: Watchman crawl failed. Retrying once with node crawler.
@@ -31,23 +25,17 @@ exports[`HasteMap tries to crawl using node as a fallback 1`] = `
 `;
 
 exports[`HasteMap warns on duplicate mock files 1`] = `
-"jest-haste-map: duplicate manual mock found:
-  Module name: subdir/Blueberry
-  Duplicate Mock path: /project/fruits2/__mocks__/subdir/Blueberry.js
-This warning is caused by two manual mock files with the same file name.
-Jest will use the mock file found in: 
-/project/fruits2/__mocks__/subdir/Blueberry.js
- Please delete one of the following two files: 
- /project/fruits1/__mocks__/subdir/Blueberry.js
-/project/fruits2/__mocks__/subdir/Blueberry.js
-
+"jest-haste-map: duplicate manual mock found: subdir/Blueberry
+  The following files share their name; please delete one of them:
+    * <rootDir>/fruits1/__mocks__/subdir/Blueberry.js
+    * <rootDir>/fruits2/__mocks__/subdir/Blueberry.js
 "
 `;
 
 exports[`HasteMap warns on duplicate module ids 1`] = `
-"jest-haste-map: Haste module naming collision:
-  Duplicate module name: Strawberry
-  Paths: /project/fruits/other/Strawberry.js collides with /project/fruits/Strawberry.js
-
-This warning is caused by \`hasteImpl\` returning the same name for different files."
+"jest-haste-map: Haste module naming collision: Strawberry
+  The following files share their name; please adjust your hasteImpl:
+    * <rootDir>/fruits/Strawberry.js
+    * <rootDir>/fruits/other/Strawberry.js
+"
 `;
diff --git a/packages/jest-haste-map/src/__tests__/index.test.js b/packages/jest-haste-map/src/__tests__/index.test.js
index e200fb612b6b..68b3aa4e226b 100644
--- a/packages/jest-haste-map/src/__tests__/index.test.js
+++ b/packages/jest-haste-map/src/__tests__/index.test.js
@@ -128,6 +128,7 @@ const useBuitinsInContext = value => {
 };
 
 let consoleWarn;
+let consoleError;
 let defaultConfig;
 let fs;
 let H;
@@ -180,7 +181,10 @@ describe('HasteMap', () => {
     fs = require('graceful-fs');
 
     consoleWarn = console.warn;
+    consoleError = console.error;
+
     console.warn = jest.fn();
+    console.error = jest.fn();
 
     HasteMap = require('../');
     H = HasteMap.H;
@@ -203,6 +207,7 @@ describe('HasteMap', () => {
 
   afterEach(() => {
     console.warn = consoleWarn;
+    console.error = consoleError;
   });
 
   it('exports constants', () => {
@@ -522,6 +527,8 @@ describe('HasteMap', () => {
   });
 
   it('warns on duplicate mock files', () => {
+    expect.assertions(1);
+
     // Duplicate mock files for blueberry
     mockFs['/project/fruits1/__mocks__/subdir/Blueberry.js'] = `
       // Blueberry
@@ -530,10 +537,14 @@ describe('HasteMap', () => {
       // Blueberry too!
     `;
 
-    return new HasteMap({mocksPattern: '__mocks__', ...defaultConfig})
+    return new HasteMap({
+      mocksPattern: '__mocks__',
+      throwOnModuleCollision: true,
+      ...defaultConfig,
+    })
       .build()
-      .then(({__hasteMapForTest: data}) => {
-        expect(console.warn.mock.calls[0][0]).toMatchSnapshot();
+      .catch(({__hasteMapForTest: data}) => {
+        expect(console.error.mock.calls[0][0]).toMatchSnapshot();
       });
   });
 
diff --git a/packages/jest-haste-map/src/index.ts b/packages/jest-haste-map/src/index.ts
index 3a7d1926539e..88a0aa893d00 100644
--- a/packages/jest-haste-map/src/index.ts
+++ b/packages/jest-haste-map/src/index.ts
@@ -66,6 +66,7 @@ type Options = {
   retainAllFiles: boolean;
   rootDir: string;
   roots: Array<string>;
+  skipPackageJson?: boolean;
   throwOnModuleCollision?: boolean;
   useWatchman?: boolean;
   watch?: boolean;
@@ -89,6 +90,7 @@ type InternalOptions = {
   retainAllFiles: boolean;
   rootDir: string;
   roots: Array<string>;
+  skipPackageJson: boolean;
   throwOnModuleCollision: boolean;
   useWatchman: boolean;
   watch: boolean;
@@ -112,6 +114,7 @@ namespace HasteMap {
 const CHANGE_INTERVAL = 30;
 const MAX_WAIT_TIME = 240000;
 const NODE_MODULES = path.sep + 'node_modules' + path.sep;
+const PACKAGE_JSON = path.sep + 'package.json';
 
 // TypeScript doesn't like us importing from outside `rootDir`, but it doesn't
 // understand `require`.
@@ -260,6 +263,7 @@ class HasteMap extends EventEmitter {
       retainAllFiles: options.retainAllFiles,
       rootDir: options.rootDir,
       roots: Array.from(new Set(options.roots)),
+      skipPackageJson: !!options.skipPackageJson,
       throwOnModuleCollision: !!options.throwOnModuleCollision,
       useWatchman: options.useWatchman == null ? true : options.useWatchman,
       watch: !!options.watch,
@@ -436,27 +440,31 @@ class HasteMap extends EventEmitter {
         H.GENERIC_PLATFORM;
 
       const existingModule = moduleMap[platform];
+
       if (existingModule && existingModule[H.PATH] !== module[H.PATH]) {
-        const message =
-          `jest-haste-map: Haste module naming collision:\n` +
-          `  Duplicate module name: ${id}\n` +
-          `  Paths: ${fastPath.resolve(
-            rootDir,
-            module[H.PATH],
-          )} collides with ` +
-          `${fastPath.resolve(rootDir, existingModule[H.PATH])}\n\nThis ` +
-          `${this._options.throwOnModuleCollision ? 'error' : 'warning'} ` +
-          `is caused by \`hasteImpl\` returning the same name for different` +
-          ` files.`;
+        const method = this._options.throwOnModuleCollision ? 'error' : 'warn';
+
+        this._console[method](
+          [
+            'jest-haste-map: Haste module naming collision: ' + id,
+            '  The following files share their name; please adjust your hasteImpl:',
+            '    * <rootDir>' + path.sep + existingModule[H.PATH],
+            '    * <rootDir>' + path.sep + module[H.PATH],
+            '',
+          ].join('\n'),
+        );
+
         if (this._options.throwOnModuleCollision) {
-          throw new Error(message);
+          throw new DuplicateError(existingModule[H.PATH], module[H.PATH]);
         }
-        this._console.warn(message);
+
         // We do NOT want consumers to use a module that is ambiguous.
         delete moduleMap[platform];
+
         if (Object.keys(moduleMap).length === 1) {
           map.delete(id);
         }
+
         let dupsByPlatform = hasteMap.duplicates.get(id);
         if (dupsByPlatform == null) {
           dupsByPlatform = new Map();
@@ -557,18 +565,26 @@ class HasteMap extends EventEmitter {
     ) {
       const mockPath = getMockName(filePath);
       const existingMockPath = mocks.get(mockPath);
+
       if (existingMockPath) {
-        this._console.warn(
-          `jest-haste-map: duplicate manual mock found:\n` +
-            `  Module name: ${mockPath}\n` +
-            `  Duplicate Mock path: ${filePath}\nThis warning ` +
-            `is caused by two manual mock files with the same file name.\n` +
-            `Jest will use the mock file found in: \n` +
-            `${filePath}\n` +
-            ` Please delete one of the following two files: \n ` +
-            `${path.join(rootDir, existingMockPath)}\n${filePath}\n\n`,
+        const secondMockPath = fastPath.relative(rootDir, filePath);
+        const method = this._options.throwOnModuleCollision ? 'error' : 'warn';
+
+        this._console[method](
+          [
+            'jest-haste-map: duplicate manual mock found: ' + mockPath,
+            '  The following files share their name; please delete one of them:',
+            '    * <rootDir>' + path.sep + existingMockPath,
+            '    * <rootDir>' + path.sep + secondMockPath,
+            '',
+          ].join('\n'),
         );
+
+        if (this._options.throwOnModuleCollision) {
+          throw new DuplicateError(existingMockPath, secondMockPath);
+        }
       }
+
       mocks.set(mockPath, relativeFilePath);
     }
 
@@ -627,6 +643,12 @@ class HasteMap extends EventEmitter {
     }
 
     for (const relativeFilePath of hasteMap.files.keys()) {
+      if (
+        this._options.skipPackageJson &&
+        relativeFilePath.endsWith(PACKAGE_JSON)
+      ) {
+        continue;
+      }
       // SHA-1, if requested, should already be present thanks to the crawler.
       const filePath = fastPath.resolve(
         this._options.rootDir,
@@ -1070,9 +1092,22 @@ class HasteMap extends EventEmitter {
   }
 
   static H: HType;
+  static DuplicateError: typeof DuplicateError;
   static ModuleMap: typeof HasteModuleMap;
 }
 
+class DuplicateError extends Error {
+  mockPath1: string;
+  mockPath2: string;
+
+  constructor(mockPath1: string, mockPath2: string) {
+    super('Duplicated files or mocks. Please check the console for more info');
+
+    this.mockPath1 = mockPath1;
+    this.mockPath2 = mockPath2;
+  }
+}
+
 function copy<T extends Object>(object: T): T {
   return Object.assign(Object.create(null), object);
 }
@@ -1082,6 +1117,7 @@ function copyMap<K, V>(input: Map<K, V>): Map<K, V> {
 }
 
 HasteMap.H = H;
+HasteMap.DuplicateError = DuplicateError;
 HasteMap.ModuleMap = HasteModuleMap;
 
 export = HasteMap;
diff --git a/packages/jest-jasmine2/src/jasmine/Env.js b/packages/jest-jasmine2/src/jasmine/Env.js
index 49e8963980b7..c1e6b70992b0 100644
--- a/packages/jest-jasmine2/src/jasmine/Env.js
+++ b/packages/jest-jasmine2/src/jasmine/Env.js
@@ -586,13 +586,24 @@ export default function(j$) {
         message = check.message;
       }
 
-      currentRunnable().addExpectationResult(false, {
+      const errorAsErrorObject = checkIsError ? error : new Error(message);
+      const runnable = currentRunnable();
+
+      if (!runnable) {
+        errorAsErrorObject.message =
+          'Caught error after test environment was torn down\n\n' +
+          errorAsErrorObject.message;
+
+        throw errorAsErrorObject;
+      }
+
+      runnable.addExpectationResult(false, {
         matcherName: '',
         passed: false,
         expected: '',
         actual: '',
         message,
-        error: checkIsError ? error : new Error(message),
+        error: errorAsErrorObject,
       });
     };
   }
diff --git a/packages/jest-repl/package.json b/packages/jest-repl/package.json
index 8c9abb3ec472..f4bb47655945 100644
--- a/packages/jest-repl/package.json
+++ b/packages/jest-repl/package.json
@@ -8,7 +8,10 @@
   },
   "license": "MIT",
   "main": "build/index.js",
+  "types": "build/index.d.ts",
   "dependencies": {
+    "@jest/transform": "^24.1.0",
+    "@jest/types": "^24.1.0",
     "jest-config": "^24.1.0",
     "jest-runtime": "^24.1.0",
     "jest-validate": "^24.0.0",
diff --git a/packages/jest-repl/src/cli/args.js b/packages/jest-repl/src/cli/args.ts
similarity index 88%
rename from packages/jest-repl/src/cli/args.js
rename to packages/jest-repl/src/cli/args.ts
index c5d29b013765..b0c72fd6e3c4 100644
--- a/packages/jest-repl/src/cli/args.js
+++ b/packages/jest-repl/src/cli/args.ts
@@ -4,15 +4,13 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
  */
 
 import Runtime from 'jest-runtime';
 
 export const usage = 'Usage: $0 [--config=<pathToConfigFile>]';
 
-export const options = {
-  ...Runtime.getCLIOptions(),
+export const options = Object.assign({}, Runtime.getCLIOptions(), {
   replname: {
     alias: 'r',
     description:
@@ -20,4 +18,4 @@ export const options = {
       'transformed. For example, "repl.ts" if using a TypeScript transformer.',
     type: 'string',
   },
-};
+});
diff --git a/packages/jest-repl/src/cli/index.js b/packages/jest-repl/src/cli/index.ts
similarity index 74%
rename from packages/jest-repl/src/cli/index.js
rename to packages/jest-repl/src/cli/index.ts
index b9a0abaf9c3b..5bbf3f975c20 100644
--- a/packages/jest-repl/src/cli/index.js
+++ b/packages/jest-repl/src/cli/index.ts
@@ -5,26 +5,26 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
  */
 
-import path from 'path';
-
 import Runtime from 'jest-runtime';
 import yargs from 'yargs';
+// @ts-ignore: Wait for jest-validate to get migrated
 import {validateCLIOptions} from 'jest-validate';
 import {deprecationEntries} from 'jest-config';
-import {version as VERSION} from '../../package.json';
 import * as args from './args';
 
-const REPL_SCRIPT = path.resolve(__dirname, './repl.js');
+const {version: VERSION} = require('../../package.json');
+
+const REPL_SCRIPT = require.resolve('./repl.js');
 
-module.exports = function() {
+export = function() {
   const argv = yargs.usage(args.usage).options(args.options).argv;
 
   validateCLIOptions(argv, {...args.options, deprecationEntries});
 
   argv._ = [REPL_SCRIPT];
 
+  // @ts-ignore: not the same arguments
   Runtime.runCLI(argv, [`Jest REPL v${VERSION}`]);
 };
diff --git a/packages/jest-repl/src/cli/repl.js b/packages/jest-repl/src/cli/repl.ts
similarity index 70%
rename from packages/jest-repl/src/cli/repl.js
rename to packages/jest-repl/src/cli/repl.ts
index 6a0b8fa5ccea..66f5725ecbed 100644
--- a/packages/jest-repl/src/cli/repl.js
+++ b/packages/jest-repl/src/cli/repl.ts
@@ -5,30 +5,37 @@
  * 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, ProjectConfig} from 'types/Config';
-
-declare var jestGlobalConfig: GlobalConfig;
-declare var jestProjectConfig: ProjectConfig;
-declare var jest: Object;
+declare const jestGlobalConfig: Config.GlobalConfig;
+declare const jestProjectConfig: Config.ProjectConfig;
 
 import path from 'path';
 import repl from 'repl';
 import vm from 'vm';
+import {Transformer} from '@jest/transform';
+import {Config} from '@jest/types';
 
-let transformer;
+let transformer: Transformer;
 
-const evalCommand = (cmd, context, filename, callback, config) => {
+const evalCommand: repl.REPLEval = (
+  cmd: string,
+  _context: any,
+  _filename: string,
+  callback: (e: Error | null, result?: any) => void,
+) => {
   let result;
   try {
     if (transformer) {
-      cmd = transformer.process(
+      const transformResult = transformer.process(
         cmd,
         jestGlobalConfig.replname || 'jest.js',
         jestProjectConfig,
       );
+      cmd =
+        typeof transformResult === 'string'
+          ? transformResult
+          : transformResult.code;
     }
     result = vm.runInThisContext(cmd);
   } catch (e) {
@@ -37,7 +44,7 @@ const evalCommand = (cmd, context, filename, callback, config) => {
   return callback(null, result);
 };
 
-const isRecoverableError = error => {
+const isRecoverableError = (error: Error) => {
   if (error && error.name === 'SyntaxError') {
     return [
       'Unterminated template',
@@ -59,7 +66,6 @@ if (jestProjectConfig.transform) {
     }
   }
   if (transformerPath) {
-    /* $FlowFixMe */
     transformer = require(transformerPath);
     if (typeof transformer.process !== 'function') {
       throw new TypeError(
@@ -69,17 +75,15 @@ if (jestProjectConfig.transform) {
   }
 }
 
-const replInstance = repl.start({
+const replInstance: repl.REPLServer = repl.start({
   eval: evalCommand,
   prompt: '\u203A ',
   useGlobal: true,
 });
 
-// $FlowFixMe: https://github.com/facebook/flow/pull/4713
-replInstance.context.require = moduleName => {
+replInstance.context.require = (moduleName: string) => {
   if (/(\/|\\|\.)/.test(moduleName)) {
     moduleName = path.resolve(process.cwd(), moduleName);
   }
-  /* $FlowFixMe */
   return require(moduleName);
 };
diff --git a/packages/jest-repl/tsconfig.json b/packages/jest-repl/tsconfig.json
new file mode 100644
index 000000000000..98a536c2c508
--- /dev/null
+++ b/packages/jest-repl/tsconfig.json
@@ -0,0 +1,15 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "build"
+  },
+  "references": [
+    {"path": "../jest-config"},
+    {"path": "../jest-runtime"},
+    {"path": "../jest-transform"},
+    {"path": "../jest-types"}
+    // TODO: Wait for this to get migrated
+    // {"path": "../jest-validate"}
+  ]
+}
diff --git a/packages/jest-runtime/src/__tests__/runtime_require_mock.test.js b/packages/jest-runtime/src/__tests__/runtime_require_mock.test.js
index b80ff9e500c5..c63697b44a25 100644
--- a/packages/jest-runtime/src/__tests__/runtime_require_mock.test.js
+++ b/packages/jest-runtime/src/__tests__/runtime_require_mock.test.js
@@ -8,8 +8,6 @@
 
 'use strict';
 
-const path = require('path');
-
 let createRuntime;
 const consoleWarn = console.warn;
 
@@ -137,29 +135,6 @@ describe('Runtime', () => {
         }).toThrow();
       }));
 
-    it('uses the closest manual mock when duplicates exist', () => {
-      console.warn = jest.fn();
-      return createRuntime(__filename, {
-        rootDir: path.resolve(
-          path.dirname(__filename),
-          'test_root_with_dup_mocks',
-        ),
-      }).then(runtime => {
-        expect(console.warn).toBeCalled();
-        const exports1 = runtime.requireMock(
-          runtime.__mockRootPath,
-          './subdir1/my_module',
-        );
-        expect(exports1.modulePath).toEqual('subdir1/__mocks__/my_module.js');
-
-        const exports2 = runtime.requireMock(
-          runtime.__mockRootPath,
-          './subdir2/my_module',
-        );
-        expect(exports2.modulePath).toEqual('subdir2/__mocks__/my_module.js');
-      });
-    });
-
     it('uses manual mocks when using a custom resolver', () =>
       createRuntime(__filename, {
         // using the default resolver as a custom resolver