feat: added an option to disable ts-node (#15161)

.github/workflows/nodejs.yml

@@ -53,6 +53,8 @@ jobs:
         run: yarn verify-old-ts
       - name: run ESLint with type info
         run: yarn lint-ts-files
+      - name: Run tests depending on type information
+        run: yarn test-with-type-info
 
   typecheck:
     name: Typecheck Examples and Tests

CHANGELOG.md

@@ -11,6 +11,7 @@
 - `[jest-config]` [**BREAKING**] Update `testMatch` and `testRegex` default option for supporting `mjs`, `cjs`, `mts`, and `cts` ([#14584](https://github.com/jestjs/jest/pull/14584))
 - `[jest-config]` Loads config file from provided path in `package.json` ([#14044](https://github.com/facebook/jest/pull/14044))
 - `[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/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

@@ -59,6 +59,8 @@ export default async (): Promise<Config> => {
 
 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 configuration files without typechecking, You can set `JEST_CONFIG_TRANSPILE_ONLY` environment variable to `true` (case insensitive).
+
 :::
 
 The configuration also can be stored in a JSON file as a plain object:

e2e/__tests__/jest.config.ts.test.ts

@@ -6,6 +6,7 @@
  */
 
 import * as path from 'path';
+import * as fs from 'graceful-fs';
 import {cleanup, extractSummary, writeFiles} from '../Utils';
 import runJest from '../runJest';
 
@@ -73,17 +74,44 @@ test('traverses directory tree up until it finds jest.config', () => {
   expect(summary).toMatchSnapshot();
 });
 
-test('it does type check the config', () => {
-  writeFiles(DIR, {
-    '__tests__/a-giraffe.js': "test('giraffe', () => expect(1).toBe(1));",
-    'jest.config.ts': 'export default { testTimeout: "10000" }',
-    'package.json': '{}',
-  });
+const jestPath = require.resolve('jest');
+const jestTypesPath = jestPath.replace(/\.js$/, '.d.ts');
+const jestTypesExists = fs.existsSync(jestTypesPath);
 
-  const {stderr, exitCode} = runJest(DIR, ['-w=1', '--ci=false']);
-  expect(stderr).toMatch('must be of type');
-  expect(exitCode).toBe(1);
-});
+(jestTypesExists ? test : test.skip).each([true, false])(
+  'check the config disabled (skip type check: %p)',
+  skipTypeCheck => {
+    writeFiles(DIR, {
+      '__tests__/a-giraffe.js': "test('giraffe', () => expect(1).toBe(1));",
+      'jest.config.ts': `
+      import {Config} from 'jest';
+      const config: Config = { testTimeout: "10000" };
+      export default config;
+    `,
+      'package.json': '{}',
+    });
+
+    const typeErrorString =
+      "TS2322: Type 'string' is not assignable to type 'number'.";
+    const runtimeErrorString = 'Option "testTimeout" must be of type:';
+
+    const {stderr, exitCode} = runJest(DIR, ['-w=1', '--ci=false'], {
+      env: {
+        JEST_CONFIG_TRANSPILE_ONLY: skipTypeCheck ? 'true' : undefined,
+      },
+    });
+
+    if (skipTypeCheck) {
+      expect(stderr).not.toMatch(typeErrorString);
+      expect(stderr).toMatch(runtimeErrorString);
+    } else {
+      expect(stderr).toMatch(typeErrorString);
+      expect(stderr).not.toMatch(runtimeErrorString);
+    }
+
+    expect(exitCode).toBe(1);
+  },
+);
 
 test('invalid JS in jest.config.ts', () => {
   writeFiles(DIR, {

package.json

@@ -111,6 +111,7 @@
     "test-leak": "yarn jest -i --detectLeaks --color jest-mock jest-diff jest-repl pretty-format",
     "test-ts": "yarn jest --config jest.config.ts.mjs",
     "test-types": "yarn tstyche",
+    "test-with-type-info": "yarn jest e2e/__tests__/jest.config.ts.test.ts",
     "test": "yarn lint && yarn jest",
     "typecheck": "yarn typecheck:examples && yarn typecheck:tests",
     "typecheck:examples": "tsc -p examples/expect-extend && tsc -p examples/typescript",

packages/jest-config/src/readConfigFileAndSetRootDir.ts

@@ -6,6 +6,7 @@
  */
 
 import * as path from 'path';
+import {isNativeError} from 'util/types';
 import * as fs from 'graceful-fs';
 import parseJson = require('parse-json');
 import stripJsonComments = require('strip-json-comments');
@@ -124,9 +125,14 @@ async function registerTsNode(): Promise<Service> {
       moduleTypes: {
         '**': 'cjs',
       },
+      transpileOnly:
+        process.env.JEST_CONFIG_TRANSPILE_ONLY?.toLowerCase() === 'true',
     });
-  } catch (error: any) {
-    if (error.code === 'ERR_MODULE_NOT_FOUND') {
+  } catch (error) {
+    if (
+      isNativeError(error) &&
+      (error as NodeJS.ErrnoException).code === 'ERR_MODULE_NOT_FOUND'
+    ) {
       throw new Error(
         `Jest: 'ts-node' is required for the TypeScript configuration files. Make sure it is installed\nError: ${error.message}`,
       );