feat: add async support to babel-jest (#11192)

Author: SimenB

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ### Features
 
+- `[babel-jest]` Add async transformation ([#11192](https://github.com/facebook/jest/pull/11192))
 - `[jest-changed-files]` Use '--' to separate paths from revisions ([#11160](https://github.com/facebook/jest/pull/11160))
 - `[jest-circus]` [**BREAKING**] Fail tests when multiple `done()` calls are made ([#10624](https://github.com/facebook/jest/pull/10624))
 - `[jest-circus, jest-jasmine2]` [**BREAKING**] Fail the test instead of just warning when describe returns a value ([#10947](https://github.com/facebook/jest/pull/10947))

e2e/__tests__/__snapshots__/transform.test.ts.snap

@@ -6,7 +6,7 @@ FAIL __tests__/ignoredFile.test.js
 
     babel-jest: Babel ignores __tests__/ignoredFile.test.js - make sure to include the file in Jest's transformIgnorePatterns as well.
 
-      at loadBabelConfig (../../../packages/babel-jest/build/index.js:195:13)
+      at assertLoadedBabelConfig (../../../packages/babel-jest/build/index.js:130:11)
 `;
 
 exports[`babel-jest instruments only specific files and collects coverage 1`] = `

e2e/__tests__/transform.test.ts

@@ -264,4 +264,21 @@ onNodeVersions('^12.17.0 || >=13.2.0', () => {
       expect(json.numPassedTests).toBe(1);
     });
   });
+
+  describe('babel-jest-async', () => {
+    const dir = path.resolve(__dirname, '../transform/babel-jest-async');
+
+    beforeAll(() => {
+      runYarnInstall(dir);
+    });
+
+    it("should use babel-jest's async transforms", () => {
+      const {json, stderr} = runWithJson(dir, ['--no-cache'], {
+        nodeOptions: '--experimental-vm-modules',
+      });
+      expect(stderr).toMatch(/PASS/);
+      expect(json.success).toBe(true);
+      expect(json.numPassedTests).toBe(1);
+    });
+  });
 });

e2e/transform/babel-jest-async/__tests__/babelJest.test.js

@@ -0,0 +1,12 @@
+/**
+ * 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 nullReturningFunc from '../only-file-to-transform.js';
+
+it('strips flowtypes using babel-jest', () => {
+  expect(nullReturningFunc()).toBe(null);
+});

e2e/transform/babel-jest-async/only-file-to-transform.js

@@ -0,0 +1,10 @@
+/**
+ * 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.
+ */
+
+const someFunction = (): null => null;
+
+export default someFunction;

e2e/transform/babel-jest-async/package.json

@@ -0,0 +1,12 @@
+{
+  "type": "module",
+  "dependencies": {
+    "@babel/preset-flow": "^7.0.0"
+  },
+  "jest": {
+    "testEnvironment": "node",
+    "transform": {
+      "only-file-to-transform\\.js$": "<rootDir>/transformer.js"
+    }
+  }
+}

e2e/transform/babel-jest-async/transformer.js

@@ -0,0 +1,19 @@
+/**
+ * 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 {fileURLToPath} from 'url';
+import babelJest from 'babel-jest';
+
+export default {
+  ...babelJest.default.createTransformer({
+    presets: ['@babel/preset-flow'],
+    root: fileURLToPath(import.meta.url),
+  }),
+  // remove the synchronous functions
+  getCacheKey: undefined,
+  process: undefined,
+};

e2e/transform/babel-jest-async/yarn.lock

@@ -0,0 +1,56 @@
+# This file is generated by running "yarn install" inside your project.
+# Manual changes might be lost - proceed with caution!
+
+__metadata:
+  version: 4
+  cacheKey: 7
+
+"@babel/helper-plugin-utils@npm:^7.12.13, @babel/helper-plugin-utils@npm:^7.13.0":
+  version: 7.13.0
+  resolution: "@babel/helper-plugin-utils@npm:7.13.0"
+  checksum: 229ac1917b43ad38732d2d4a9a826f87d8945719249efe1d6191f3e25ba6027a289af70380d82d62a03fc9e82558a0ea6f12739cbb55b64bb280d6b511b4ca65
+  languageName: node
+  linkType: hard
+
+"@babel/plugin-syntax-flow@npm:^7.12.13":
+  version: 7.12.13
+  resolution: "@babel/plugin-syntax-flow@npm:7.12.13"
+  dependencies:
+    "@babel/helper-plugin-utils": ^7.12.13
+  peerDependencies:
+    "@babel/core": ^7.0.0-0
+  checksum: de8845354dda62b7857a518a54f85bf30809ed1d7cc5ace93ced6da16d095cba78487d18651f1b2277db58d8e749cb910c703f96529af198369226e374df5f73
+  languageName: node
+  linkType: hard
+
+"@babel/plugin-transform-flow-strip-types@npm:^7.12.13":
+  version: 7.13.0
+  resolution: "@babel/plugin-transform-flow-strip-types@npm:7.13.0"
+  dependencies:
+    "@babel/helper-plugin-utils": ^7.13.0
+    "@babel/plugin-syntax-flow": ^7.12.13
+  peerDependencies:
+    "@babel/core": ^7.0.0-0
+  checksum: 60903f5e3619b4f4a19d6d00a4d10c5b97566f5d4c56dd35ccdaa6e621fc955ec4003f12cd73ec99475894a7eca6a34aa4b38f87c7c81e93d5fe03d006aae77b
+  languageName: node
+  linkType: hard
+
+"@babel/preset-flow@npm:^7.0.0":
+  version: 7.12.13
+  resolution: "@babel/preset-flow@npm:7.12.13"
+  dependencies:
+    "@babel/helper-plugin-utils": ^7.12.13
+    "@babel/plugin-transform-flow-strip-types": ^7.12.13
+  peerDependencies:
+    "@babel/core": ^7.0.0-0
+  checksum: 47fe1001194a57fbdb33250adcb4c3aa9ff551cfb4eea1a16b123ff5fe78730a7ebfb839bacbe18390fc50fa4bf67fdd5293703b859876de45d52f50d4da0d44
+  languageName: node
+  linkType: hard
+
+"root-workspace-0b6124@workspace:.":
+  version: 0.0.0-use.local
+  resolution: "root-workspace-0b6124@workspace:."
+  dependencies:
+    "@babel/preset-flow": ^7.0.0
+  languageName: unknown
+  linkType: soft

packages/babel-jest/package.json

@@ -30,7 +30,7 @@
     "@types/graceful-fs": "^4.1.3"
   },
   "peerDependencies": {
-    "@babel/core": "^7.0.0"
+    "@babel/core": "^7.8.0"
   },
   "engines": {
     "node": "^10.13.0 || ^12.13.0 || ^14.15.0 || >=15.0.0"

packages/babel-jest/src/__tests__/index.ts

@@ -14,6 +14,9 @@ jest.mock('../loadBabelConfig', () => {
 
   return {
     loadPartialConfig: jest.fn((...args) => actual.loadPartialConfig(...args)),
+    loadPartialConfigAsync: jest.fn((...args) =>
+      actual.loadPartialConfigAsync(...args),
+    ),
   };
 });
 
@@ -49,6 +52,25 @@ test('Returns source string with inline maps when no transformOptions is passed'
   expect(JSON.stringify(result.map!.sourcesContent)).toMatch('customMultiply');
 });
 
+test('Returns source string with inline maps when no transformOptions is passed async', async () => {
+  const result: any = await babelJest.processAsync!(
+    sourceString,
+    'dummy_path.js',
+    {
+      config: makeProjectConfig(),
+      configString: JSON.stringify(makeProjectConfig()),
+      instrument: false,
+    },
+  );
+  expect(typeof result).toBe('object');
+  expect(result.code).toBeDefined();
+  expect(result.map).toBeDefined();
+  expect(result.code).toMatch('//# sourceMappingURL');
+  expect(result.code).toMatch('customMultiply');
+  expect(result.map!.sources).toEqual(['dummy_path.js']);
+  expect(JSON.stringify(result.map!.sourcesContent)).toMatch('customMultiply');
+});
+
 describe('caller option correctly merges from defaults and options', () => {
   test.each([
     [