feat(expect): migrate to ESM (#12344)

.eslintrc.js

@@ -42,8 +42,6 @@ module.exports = {
         '@typescript-eslint/prefer-ts-expect-error': 'error',
         // TS verifies this
         'consistent-return': 'off',
-        // Since we do `export =`. Remove for Jest 27
-        'import/default': 'off',
         'no-dupe-class-members': 'off',
         'no-unused-vars': 'off',
       },

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ### Features
 
+- `[expect]` [**BREAKING**] Migrate to ESM ([#12344](https://github.com/facebook/jest/pull/12344))
 - `[jest-environment-jsdom]` [**BREAKING**] Add default `browser` condition to `exportConditions` for `jsdom` environment ([#11924](https://github.com/facebook/jest/pull/11924))
 - `[jest-environment-jsdom]` [**BREAKING**] Migrate to ESM ([#12340](https://github.com/facebook/jest/pull/12340))
 - `[jest-environment-node]` [**BREAKING**] Add default `node` and `node-addon` conditions to `exportConditions` for `node` environment ([#11924](https://github.com/facebook/jest/pull/11924))

babel.config.js

@@ -17,7 +17,6 @@ module.exports = {
   overrides: [
     {
       plugins: [
-        'babel-plugin-replace-ts-export-assignment',
         require.resolve(
           './scripts/babel-plugin-jest-replace-ts-require-assignment.js',
         ),

package.json

@@ -25,7 +25,6 @@
     "@typescript-eslint/parser": "^4.1.0",
     "ansi-regex": "^5.0.1",
     "ansi-styles": "^5.0.0",
-    "babel-plugin-replace-ts-export-assignment": "^0.0.2",
     "camelcase": "^6.2.0",
     "chalk": "^4.0.0",
     "chokidar": "^3.3.0",

packages/expect/src/__tests__/matchers.test.js

@@ -9,7 +9,7 @@ const chalk = require('chalk');
 const Immutable = require('immutable');
 const {alignedAnsiStyleSerializer} = require('@jest/test-utils');
 const {stringify} = require('jest-matcher-utils');
-const jestExpect = require('../');
+const {expect: jestExpect} = require('../');
 const chalkEnabled = chalk.enabled;
 
 expect.addSnapshotSerializer(alignedAnsiStyleSerializer);

packages/expect/src/index.ts

@@ -41,16 +41,17 @@ import type {
   AsyncExpectationResult,
   Expect,
   ExpectationResult,
-  MatcherState as JestMatcherState,
-  Matchers as MatcherInterface,
+  MatcherState,
   MatchersObject,
   PromiseMatcherFn,
   RawMatcherFn,
   SyncExpectationResult,
   ThrowingMatcherFn,
 } from './types';
 
-class JestAssertionError extends Error {
+export type {Expect, MatcherState, Matchers} from './types';
+
+export class JestAssertionError extends Error {
   matcherResult?: Omit<SyncExpectationResult, 'message'> & {message: string};
 }
 
@@ -63,7 +64,7 @@ const createToThrowErrorMatchingSnapshotMatcher = function (
   matcher: RawMatcherFn,
 ) {
   return function (
-    this: JestMatcherState,
+    this: MatcherState,
     received: any,
     testNameOrInlineSnapshot?: string,
   ) {
@@ -84,7 +85,7 @@ const getPromiseMatcher = (name: string, matcher: any) => {
   return null;
 };
 
-const expect: any = (actual: any, ...rest: Array<any>) => {
+export const expect: Expect = (actual: any, ...rest: Array<any>) => {
   if (rest.length !== 0) {
     throw new Error('Expect takes at most one argument.');
   }
@@ -252,7 +253,7 @@ const makeThrowingMatcher = (
     let throws = true;
     const utils = {...matcherUtils, iterableEquality, subsetEquality};
 
-    const matcherContext: JestMatcherState = {
+    const matcherContext: MatcherState = {
       // When throws is disabled, the matcher will not throw errors during test
       // execution but instead add them to the global matcher state. If a
       // matcher throws, test execution is normally stopped immediately. The
@@ -355,7 +356,7 @@ const makeThrowingMatcher = (
     }
   };
 
-expect.extend = <T extends JestMatcherState = JestMatcherState>(
+expect.extend = <T extends MatcherState = MatcherState>(
   matchers: MatchersObject<T>,
 ): void => setMatchers(matchers, false, expect);
 
@@ -394,7 +395,7 @@ const _validateResult = (result: any) => {
   }
 };
 
-function assertions(expected: number) {
+function assertions(expected: number): void {
   const error = new Error();
   if (Error.captureStackTrace) {
     Error.captureStackTrace(error, assertions);
@@ -405,7 +406,7 @@ function assertions(expected: number) {
     expectedAssertionsNumberError: error,
   });
 }
-function hasAssertions(...args: Array<any>) {
+function hasAssertions(...args: Array<unknown>): void {
   const error = new Error();
   if (Error.captureStackTrace) {
     Error.captureStackTrace(error, hasAssertions);
@@ -419,9 +420,9 @@ function hasAssertions(...args: Array<any>) {
 }
 
 // add default jest matchers
-setMatchers(matchers, true, expect as Expect);
-setMatchers(spyMatchers, true, expect as Expect);
-setMatchers(toThrowMatchers, true, expect as Expect);
+setMatchers(matchers, true, expect);
+setMatchers(spyMatchers, true, expect);
+setMatchers(toThrowMatchers, true, expect);
 
 expect.addSnapshotSerializer = () => void 0;
 expect.assertions = assertions;
@@ -430,11 +431,4 @@ expect.getState = getState;
 expect.setState = setState;
 expect.extractExpectedAssertionsErrors = extractExpectedAssertionsErrors;
 
-const expectExport = expect as Expect;
-
-declare namespace expectExport {
-  export type MatcherState = JestMatcherState;
-  export interface Matchers<R, T = unknown> extends MatcherInterface<R, T> {}
-}
-
-export = expectExport;
+export default expect;

packages/jest-circus/src/legacy-code-todo-rewrite/jestAdapterInit.ts

@@ -15,7 +15,7 @@ import {
   createEmptyTestResult,
 } from '@jest/test-result';
 import type {Circus, Config, Global} from '@jest/types';
-import {extractExpectedAssertionsErrors, getState, setState} from 'expect';
+import {Expect, expect} from 'expect';
 import {bind} from 'jest-each';
 import {formatExecError, formatResultsErrors} from 'jest-message-util';
 import {
@@ -33,7 +33,7 @@ import {
 } from '../state';
 import testCaseReportHandler from '../testCaseReportHandler';
 import {getTestID} from '../utils';
-import createExpect, {Expect} from './jestExpect';
+import createExpect from './jestExpect';
 
 type Process = NodeJS.Process;
 
@@ -162,7 +162,7 @@ export const initialize = async ({
     updateSnapshot,
   });
   // @ts-expect-error: snapshotState is a jest extension of `expect`
-  setState({snapshotState, testPath});
+  expect.setState({snapshotState, testPath});
 
   addEventHandler(handleSnapshotStateAfterRetry(snapshotState));
   if (sendMessageToJest) {
@@ -279,7 +279,7 @@ const handleSnapshotStateAfterRetry =
 const eventHandler = async (event: Circus.Event) => {
   switch (event.name) {
     case 'test_start': {
-      setState({currentTestName: getTestID(event.test)});
+      expect.setState({currentTestName: getTestID(event.test)});
       break;
     }
     case 'test_done': {
@@ -291,7 +291,7 @@ const eventHandler = async (event: Circus.Event) => {
 };
 
 const _addExpectedAssertionErrors = (test: Circus.TestEntry) => {
-  const failures = extractExpectedAssertionsErrors();
+  const failures = expect.extractExpectedAssertionsErrors();
   const errors = failures.map(failure => failure.error);
   test.errors = test.errors.concat(errors);
 };
@@ -300,8 +300,8 @@ const _addExpectedAssertionErrors = (test: Circus.TestEntry) => {
 // test execution and add them to the test result, potentially failing
 // a passing test.
 const _addSuppressedErrors = (test: Circus.TestEntry) => {
-  const {suppressedErrors} = getState();
-  setState({suppressedErrors: []});
+  const {suppressedErrors} = expect.getState();
+  expect.setState({suppressedErrors: []});
   if (suppressedErrors.length) {
     test.errors = test.errors.concat(suppressedErrors);
   }

packages/jest-circus/src/legacy-code-todo-rewrite/jestExpect.ts

@@ -6,7 +6,7 @@
  */
 
 import type {Config} from '@jest/types';
-import expect = require('expect');
+import {Expect, expect} from 'expect';
 import {
   addSerializer,
   toMatchInlineSnapshot,
@@ -15,8 +15,6 @@ import {
   toThrowErrorMatchingSnapshot,
 } from 'jest-snapshot';
 
-export type Expect = typeof expect;
-
 export default function jestExpect(
   config: Pick<Config.GlobalConfig, 'expand'>,
 ): Expect {

packages/jest-circus/src/types.ts

@@ -5,9 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// Used as type
 import type {Circus} from '@jest/types';
-import type expect = require('expect');
+import type {Expect} from 'expect';
 
 export const STATE_SYM = Symbol(
   'JEST_STATE_SYMBOL',
@@ -26,7 +25,7 @@ declare global {
       STATE_SYM_SYMBOL: Circus.State;
       RETRY_TIMES_SYMBOL: string;
       TEST_TIMEOUT_SYMBOL: number;
-      expect: typeof expect;
+      expect: Expect;
     }
   }
 }

packages/jest-globals/src/index.ts

@@ -7,11 +7,11 @@
 
 import type {Jest} from '@jest/environment';
 import type {Global} from '@jest/types';
-import type importedExpect = require('expect');
+import type {Expect} from 'expect';
 
 export declare const jest: Jest;
 
-export declare const expect: typeof importedExpect;
+export declare const expect: Expect;
 
 export declare const it: Global.GlobalAdditions['it'];
 export declare const test: Global.GlobalAdditions['test'];

packages/jest-jasmine2/src/jestExpect.ts

@@ -8,7 +8,7 @@
 /* eslint-disable local/prefer-spread-eventually */
 
 import type {Global} from '@jest/types';
-import expect = require('expect');
+import {MatcherState, expect} from 'expect';
 import {
   addSerializer,
   toMatchInlineSnapshot,
@@ -42,7 +42,7 @@ export default function jestExpect(config: {expand: boolean}): void {
     const jestMatchersObject = Object.create(null);
     Object.keys(jasmineMatchersObject).forEach(name => {
       jestMatchersObject[name] = function (
-        this: expect.MatcherState,
+        this: MatcherState,
         ...args: Array<unknown>
       ): RawMatcherFn {
         // use "expect.extend" if you need to use equality testers (via this.equal)

packages/jest-jasmine2/src/setup_jest_globals.ts

@@ -6,7 +6,7 @@
  */
 
 import type {Config, Global} from '@jest/types';
-import {extractExpectedAssertionsErrors, getState, setState} from 'expect';
+import {expect} from 'expect';
 import {
   SnapshotState,
   addSerializer,
@@ -33,8 +33,8 @@ export type SetupOptions = {
 // test execution and add them to the test result, potentially failing
 // a passing test.
 const addSuppressedErrors = (result: SpecResult) => {
-  const {suppressedErrors} = getState();
-  setState({suppressedErrors: []});
+  const {suppressedErrors} = expect.getState();
+  expect.setState({suppressedErrors: []});
   if (suppressedErrors.length) {
     result.status = 'failed';
 
@@ -52,7 +52,7 @@ const addSuppressedErrors = (result: SpecResult) => {
 };
 
 const addAssertionErrors = (result: SpecResult) => {
-  const assertionErrors = extractExpectedAssertionsErrors();
+  const assertionErrors = expect.extractExpectedAssertionsErrors();
   if (assertionErrors.length) {
     const jasmineErrors = assertionErrors.map(({actual, error, expected}) => ({
       actual,
@@ -77,7 +77,7 @@ const patchJasmine = () => {
         };
         const onStart = attr.onStart;
         attr.onStart = (context: JasmineSpec) => {
-          setState({currentTestName: context.getFullName()});
+          expect.setState({currentTestName: context.getFullName()});
           onStart && onStart.call(attr, context);
         };
         super(attr);
@@ -115,7 +115,7 @@ export default async function setupJestGlobals({
     updateSnapshot,
   });
   // @ts-expect-error: snapshotState is a jest extension of `expect`
-  setState({snapshotState, testPath});
+  expect.setState({snapshotState, testPath});
   // Return it back to the outer scope (test runner outside the VM).
   return snapshotState;
 }

packages/jest-jasmine2/src/types.ts

@@ -7,7 +7,7 @@
 
 import type {AssertionError} from 'assert';
 import type {Config} from '@jest/types';
-import type expect = require('expect');
+import type {Expect} from 'expect';
 import type CallTracker from './jasmine/CallTracker';
 import type Env from './jasmine/Env';
 import type JsApiReporter from './jasmine/JsApiReporter';
@@ -89,13 +89,13 @@ export type Jasmine = {
   version: string;
   testPath: Config.Path;
   addMatchers: (matchers: JasmineMatchersObject) => void;
-} & typeof expect &
+} & Expect &
   typeof globalThis;
 
 declare global {
   namespace NodeJS {
     interface Global {
-      expect: typeof expect;
+      expect: Expect;
     }
   }
 }

yarn.lock

@@ -2621,7 +2621,6 @@ __metadata:
     "@typescript-eslint/parser": ^4.1.0
     ansi-regex: ^5.0.1
     ansi-styles: ^5.0.0
-    babel-plugin-replace-ts-export-assignment: ^0.0.2
     camelcase: ^6.2.0
     chalk: ^4.0.0
     chokidar: ^3.3.0
@@ -6502,13 +6501,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"babel-plugin-replace-ts-export-assignment@npm:^0.0.2":
-  version: 0.0.2
-  resolution: "babel-plugin-replace-ts-export-assignment@npm:0.0.2"
-  checksum: da749130fe0479cd9da73f8b3aafc62e05885b12732ce0e25976a7138dad1688a03366791b12633afdd8a702e2018ec01764c4ddb0ed0dbc3783b7e75b1b148a
-  languageName: node
-  linkType: hard
-
 "babel-plugin-syntax-trailing-function-commas@npm:^7.0.0-beta.0":
   version: 7.0.0-beta.0
   resolution: "babel-plugin-syntax-trailing-function-commas@npm:7.0.0-beta.0"