feat(jest-config):Support loading TS config files via docblock loader

CHANGELOG.md

@@ -14,6 +14,7 @@
 - `[jest-config]` Allow loading `jest.config.cts` files ([#14070](https://github.com/facebook/jest/pull/14070))
 - `[jest-config]` Added an option to disable `ts-node` typechecking ([#15161](https://github.com/jestjs/jest/pull/15161))
 - `[jest-config]` Show `rootDir` in error message when a `preset` fails to load ([#15194](https://github.com/jestjs/jest/pull/15194))
+- `[jest-config]` Support loading TS config files using `esbuild-register` via docblock loader ([#15190](https://github.com/jestjs/jest/pull/15190))
 - `[@jest/core]` Group together open handles with the same stack trace ([#13417](https://github.com/jestjs/jest/pull/13417), & [#14789](https://github.com/jestjs/jest/pull/14789))
 - `[@jest/core]` Add `perfStats` to surface test setup overhead ([#14622](https://github.com/jestjs/jest/pull/14622))
 - `[@jest/core]` [**BREAKING**] Changed `--filter` to accept an object with shape `{ filtered: Array<string> }` to match [documentation](https://jestjs.io/docs/cli#--filterfile) ([#13319](https://github.com/jestjs/jest/pull/13319))

docs/Configuration.md

@@ -57,9 +57,23 @@ export default async (): Promise<Config> => {
 
 :::tip
 
-To read TypeScript configuration files Jest requires [`ts-node`](https://npmjs.com/package/ts-node). Make sure it is installed in your project.
+To read TypeScript configuration files Jest by default requires [`ts-node`](https://npmjs.com/package/ts-node). You can override this behavior by adding a `@jest-config-loader` docblock at the top of the file. Currently, [`ts-node`](https://npmjs.com/package/ts-node) and [`esbuild-register`](https://npmjs.com/package/esbuild-register) is supported. Make sure `ts-node` or the loader you specify is installed.
 
-To read configuration files without typechecking, You can set `JEST_CONFIG_TRANSPILE_ONLY` environment variable to `true` (case insensitive).
+```ts title="jest.config.ts"
+/** @jest-config-loader ts-node */
+// or
+/** @jest-config-loader esbuild-register */
+
+import type {Config} from 'jest';
+
+const config: Config = {
+  verbose: true,
+};
+
+export default config;
+```
+
+If you are using `ts-node`, you can set `JEST_CONFIG_TRANSPILE_ONLY` environment variable to `true` (case insensitive) to read configuration files without typechecking.
 
 :::
 

e2e/__tests__/multipleConfigs.ts

@@ -34,3 +34,16 @@ test('multiple configs error can be suppressed by using --config', () => {
   );
   expect(exitCode).toBe(0);
 });
+
+test('should works correctly when using different loaders in different projects', () => {
+  const {exitCode, stdout, stderr} = runJest(
+    'multi-project-multiple-configs',
+    ['--projects', 'prj-1', 'prj-2'],
+    {
+      skipPkgJsonCheck: true,
+    },
+  );
+  expect(exitCode).toBe(0);
+  console.log(stdout);
+  console.log(stderr);
+});

e2e/__tests__/readInitialOptions.test.ts

@@ -46,60 +46,27 @@ describe('readInitialOptions', () => {
     expect(config).toEqual({jestConfig: 'jest.config.js', rootDir});
     expect(configPath).toEqual(configFile);
   });
-  test('should read a jest.config.js file', async () => {
-    const configFile = resolveFixture('js-config', 'jest.config.js');
-    const rootDir = resolveFixture('js-config');
-    const {config, configPath} = await proxyReadInitialOptions(undefined, {
-      cwd: rootDir,
-    });
-    expect(config).toEqual({jestConfig: 'jest.config.js', rootDir});
-    expect(configPath).toEqual(configFile);
-  });
-  test('should read a package.json file', async () => {
-    const configFile = resolveFixture('pkg-config', 'package.json');
-    const rootDir = resolveFixture('pkg-config');
-    const {config, configPath} = await proxyReadInitialOptions(undefined, {
-      cwd: rootDir,
-    });
-    expect(config).toEqual({jestConfig: 'package.json', rootDir});
-    expect(configPath).toEqual(configFile);
-  });
-  test('should read a jest.config.ts file', async () => {
-    const configFile = resolveFixture('ts-config', 'jest.config.ts');
-    const rootDir = resolveFixture('ts-config');
-    const {config, configPath} = await proxyReadInitialOptions(undefined, {
-      cwd: rootDir,
-    });
-    expect(config).toEqual({jestConfig: 'jest.config.ts', rootDir});
-    expect(configPath).toEqual(configFile);
-  });
-  test('should read a jest.config.mjs file', async () => {
-    const configFile = resolveFixture('mjs-config', 'jest.config.mjs');
-    const rootDir = resolveFixture('mjs-config');
-    const {config, configPath} = await proxyReadInitialOptions(undefined, {
-      cwd: rootDir,
-    });
-    expect(config).toEqual({jestConfig: 'jest.config.mjs', rootDir});
-    expect(configPath).toEqual(configFile);
-  });
-  test('should read a jest.config.json file', async () => {
-    const configFile = resolveFixture('json-config', 'jest.config.json');
-    const rootDir = resolveFixture('json-config');
-    const {config, configPath} = await proxyReadInitialOptions(undefined, {
-      cwd: rootDir,
-    });
-    expect(config).toEqual({jestConfig: 'jest.config.json', rootDir});
-    expect(configPath).toEqual(configFile);
-  });
-  test('should read a jest config exporting an async function', async () => {
-    const configFile = resolveFixture('async-config', 'jest.config.js');
-    const rootDir = resolveFixture('async-config');
-    const {config, configPath} = await proxyReadInitialOptions(undefined, {
-      cwd: rootDir,
-    });
-    expect(config).toEqual({jestConfig: 'async-config', rootDir});
-    expect(configPath).toEqual(configFile);
-  });
+
+  test.each([
+    ['js-config', 'jest.config.js', 'jest.config.js'],
+    ['pkg-config', 'package.json', 'package.json'],
+    ['ts-node-config', 'jest.config.ts', 'jest.config.ts'],
+    ['ts-esbuild-register-config', 'jest.config.ts', 'jest.config.ts'],
+    ['mjs-config', 'jest.config.mjs', 'jest.config.mjs'],
+    ['json-config', 'jest.config.json', 'jest.config.json'],
+    ['async-config', 'jest.config.js', 'async-config'],
+  ])(
+    'should read %s/%s file',
+    async (directory: string, filename: string, configString: string) => {
+      const configFile = resolveFixture(directory, filename);
+      const rootDir = resolveFixture(directory);
+      const {config, configPath} = await proxyReadInitialOptions(undefined, {
+        cwd: rootDir,
+      });
+      expect(config).toEqual({jestConfig: configString, rootDir});
+      expect(configPath).toEqual(configFile);
+    },
+  );
 
   test('should be able to skip config reading, instead read from cwd', async () => {
     const expectedConfigFile = resolveFixture(
@@ -121,6 +88,16 @@ describe('readInitialOptions', () => {
     expect(configPath).toEqual(expectedConfigFile);
   });
 
+  test('should give an error when using unsupported loader', async () => {
+    const cwd = resolveFixture('ts-loader-config');
+    const error: Error = await proxyReadInitialOptions(undefined, {cwd}).catch(
+      error => error,
+    );
+    expect(error.message).toContain(
+      "Jest: 'ts-loader' is not a valid TypeScript configuration loader.",
+    );
+  });
+
   test('should give an error when there are multiple config files', async () => {
     const cwd = resolveFixture('multiple-config-files');
     const error: Error = await proxyReadInitialOptions(undefined, {cwd}).catch(

e2e/read-initial-options/ts-config/jest.config.ts → e2e/multi-project-multiple-configs/prj-1/__tests__/test.js

@@ -4,6 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  */
-export default {
-  jestConfig: 'jest.config.ts',
-};
+
+test('dummy test', () => {
+  expect(1).toBe(1);
+});

e2e/multi-project-multiple-configs/prj-1/jest.config.ts

@@ -0,0 +1,16 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @jest-config-loader esbuild-register
+ */
+
+import type {Config} from 'jest';
+
+const config: Config = {
+  displayName: 'PROJECT 1',
+};
+
+export default config;

e2e/multi-project-multiple-configs/prj-2/__tests__/test.js

@@ -0,0 +1,10 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+test('dummy test', () => {
+  expect(2).toBe(2);
+});

e2e/multi-project-multiple-configs/prj-2/jest.config.ts

@@ -0,0 +1,16 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @jest-config-loader ts-node
+ */
+
+import type {Config} from 'jest';
+
+const config: Config = {
+  displayName: 'PROJECT 2',
+};
+
+export default config;

e2e/read-initial-options/ts-esbuild-register-config/jest.config.ts

@@ -0,0 +1,16 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @jest-config-loader esbuild-register
+ */
+
+interface Config {
+  jestConfig: string;
+}
+
+export default {
+  jestConfig: 'jest.config.ts',
+} as Config;

e2e/read-initial-options/ts-loader-config/jest.config.ts

@@ -0,0 +1,16 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @jest-config-loader ts-loader
+ */
+
+interface Config {
+  jestConfig: string;
+}
+
+export default {
+  jestConfig: 'jest.config.ts',
+} as Config;

e2e/read-initial-options/ts-node-config/jest.config.ts

@@ -0,0 +1,16 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @jest-config-loader ts-node
+ */
+
+interface Config {
+  jestConfig: string;
+}
+
+export default {
+  jestConfig: 'jest.config.ts',
+} as Config;

packages/jest-config/package.json

@@ -20,12 +20,16 @@
   },
   "peerDependencies": {
     "@types/node": "*",
+    "esbuild-register": ">=3.4.0",
     "ts-node": ">=9.0.0"
   },
   "peerDependenciesMeta": {
     "@types/node": {
       "optional": true
     },
+    "esbuild-register": {
+      "optional": true
+    },
     "ts-node": {
       "optional": true
     }
@@ -42,6 +46,7 @@
     "glob": "^10.3.10",
     "graceful-fs": "^4.2.9",
     "jest-circus": "workspace:*",
+    "jest-docblock": "workspace:*",
     "jest-environment-node": "workspace:*",
     "jest-get-type": "workspace:*",
     "jest-regex-util": "workspace:*",
@@ -59,6 +64,8 @@
     "@types/graceful-fs": "^4.1.3",
     "@types/micromatch": "^4.0.7",
     "@types/parse-json": "^4.0.0",
+    "esbuild": "^0.23.0",
+    "esbuild-register": "^3.4.0",
     "semver": "^7.5.3",
     "ts-node": "^10.5.0",
     "typescript": "^5.0.4"