chore: migrate @jest/transform to TypeScript

CHANGELOG.md

@@ -43,6 +43,7 @@
 - `[@jest/transform]`: New package extracted from `jest-runtime` ([#7915](https://github.com/facebook/jest/pull/7915))
 - `[babel-plugin-jest-hoist]`: Migrate to TypeScript ([#7898](https://github.com/facebook/jest/pull/7898))
 - `[@jest/core]` Create new package, which is `jest-cli` minus `yargs` and `prompts` ([#7696](https://github.com/facebook/jest/pull/7696))
+- `[@jest/transform]`: Migrate to TypeScript ([#7918](https://github.com/facebook/jest/pull/7918))
 
 ### Performance
 

packages/babel-jest/package.json

@@ -11,15 +11,16 @@
   "main": "build/index.js",
   "types": "build/index.d.ts",
   "dependencies": {
+    "@jest/transform": "^24.1.0",
     "@jest/types": "^24.1.0",
+    "@types/babel__core": "^7.0.4",
     "babel-plugin-istanbul": "^5.1.0",
     "babel-preset-jest": "^24.1.0",
     "chalk": "^2.4.2",
     "slash": "^2.0.0"
   },
   "devDependencies": {
     "@babel/core": "^7.1.0",
-    "@types/babel__core": "^7.0.4",
     "@types/slash": "^2.0.0"
   },
   "peerDependencies": {

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

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {Config, Transform} from '@jest/types';
+import {Config} from '@jest/types';
 import babelJest from '../index';
 
 //Mock data for all the tests
@@ -30,14 +30,12 @@ test(`Returns source string with inline maps when no transformOptions is passed`
     sourceString,
     'dummy_path.js',
     (mockConfig as unknown) as Config.ProjectConfig,
-  ) as Transform.TransformedSource;
+  ) as any;
   expect(typeof result).toBe('object');
   expect(result.code).toBeDefined();
   expect(result.map).toBeDefined();
   expect(result.code).toMatch('//# sourceMappingURL');
   expect(result.code).toMatch('customMultiply');
-  // @ts-ignore: it's fine if we get wrong types, the tests will fail then
   expect(result.map.sources).toEqual(['dummy_path.js']);
-  // @ts-ignore: it's fine if we get wrong types, the tests will fail then
   expect(JSON.stringify(result.map.sourcesContent)).toMatch('customMultiply');
 });

packages/babel-jest/src/index.ts

@@ -8,12 +8,13 @@
 import crypto from 'crypto';
 import fs from 'fs';
 import path from 'path';
-import {Config, Transform} from '@jest/types';
+import {Transformer} from '@jest/transform';
+import {Config} from '@jest/types';
 import {
-  transformSync as babelTransform,
   loadPartialConfig,
-  TransformOptions,
   PartialConfig,
+  TransformOptions,
+  transformSync as babelTransform,
 } from '@babel/core';
 import chalk from 'chalk';
 import slash from 'slash';
@@ -22,12 +23,18 @@ const THIS_FILE = fs.readFileSync(__filename);
 const jestPresetPath = require.resolve('babel-preset-jest');
 const babelIstanbulPlugin = require.resolve('babel-plugin-istanbul');
 
+// Narrow down the types
+interface BabelJestTransformer extends Transformer {
+  canInstrument: true;
+  createTransformer: (options?: TransformOptions) => BabelJestTransformer;
+}
+
 const createTransformer = (
   options: TransformOptions = {},
-): Transform.Transformer => {
+): BabelJestTransformer => {
   options = {
     ...options,
-    // @ts-ignore: https://github.com/DefinitelyTyped/DefinitelyTyped/pull/32955
+    // @ts-ignore: https://github.com/DefinitelyTyped/DefinitelyTyped/pull/33118
     caller: {
       name: 'babel-jest',
       supportsStaticESM: false,
@@ -58,18 +65,15 @@ const createTransformer = (
     return babelConfig;
   }
 
-  return {
+  const transformer: BabelJestTransformer = {
     canInstrument: true,
+    createTransformer,
     getCacheKey(
-      fileData: string,
-      filename: Config.Path,
-      configString: string,
-      {
-        config,
-        instrument,
-        rootDir,
-      }: {config: Config.ProjectConfig} & Transform.CacheKeyOptions,
-    ): string {
+      fileData,
+      filename,
+      configString,
+      {config, instrument, rootDir},
+    ) {
       const babelOptions = loadBabelConfig(config.cwd, filename);
       const configPath = [
         babelOptions.config || '',
@@ -97,12 +101,7 @@ const createTransformer = (
         .update(process.env.BABEL_ENV || '')
         .digest('hex');
     },
-    process(
-      src: string,
-      filename: Config.Path,
-      config: Config.ProjectConfig,
-      transformOptions?: Transform.TransformOptions,
-    ): string | Transform.TransformedSource {
+    process(src, filename, config, transformOptions) {
       const babelOptions = {...loadBabelConfig(config.cwd, filename).options};
 
       if (transformOptions && transformOptions.instrument) {
@@ -132,13 +131,8 @@ const createTransformer = (
       return src;
     },
   };
-};
 
-const transformer = createTransformer();
-
-// FIXME: This is not part of the exported TS types. When fixed, remember to
-// move @types/babel__core to `dependencies` instead of `devDependencies`
-// (one fix is to use ESM, maybe for Jest 25?)
-transformer.createTransformer = createTransformer;
+  return transformer;
+};
 
-export = transformer;
+export = createTransformer();

packages/babel-jest/tsconfig.json

@@ -6,6 +6,7 @@
   },
   // TODO: include `babel-preset-jest` if it's ever in TS even though we don't care about its types
   "references": [
+    {"path": "../jest-transform"},
     {"path": "../jest-types"}
   ]
 }

packages/jest-transform/package.json

@@ -10,6 +10,7 @@
   "main": "build/index.js",
   "dependencies": {
     "@babel/core": "^7.1.0",
+    "@jest/types": "^24.1.0",
     "babel-plugin-istanbul": "^5.1.0",
     "chalk": "^2.0.1",
     "convert-source-map": "^1.4.0",
@@ -21,11 +22,13 @@
     "micromatch": "^3.1.10",
     "realpath-native": "^1.1.0",
     "slash": "^2.0.0",
+    "source-map": "^0.6.1",
     "write-file-atomic": "2.4.1"
   },
   "devDependencies": {
     "@types/babel__core": "^7.0.4",
     "@types/convert-source-map": "^1.5.1",
+    "@types/fast-json-stable-stringify": "^2.0.0",
     "@types/graceful-fs": "^4.1.2",
     "@types/micromatch": "^3.1.0",
     "@types/write-file-atomic": "^2.1.1"