Support outputFile option for listTests option

CHANGELOG.md

@@ -12,6 +12,7 @@
 - `[@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))
+- `[@jest/core]` Support `--outputFile` option for [`--listTests`](https://jestjs.io/docs/cli#--listtests) ([#14980](https://github.com/jestjs/jest/pull/14980))
 - `[@jest/core, @jest/test-sequencer]` [**BREAKING**] Exposes `globalConfig` & `contexts` to `TestSequencer` ([#14535](https://github.com/jestjs/jest/pull/14535), & [#14543](https://github.com/jestjs/jest/pull/14543))
 - `[jest-environment-jsdom]` [**BREAKING**] Upgrade JSDOM to v22 ([#13825](https://github.com/jestjs/jest/pull/13825))
 - `[@jest/environment-jsdom-abstract]` Introduce new package which abstracts over the `jsdom` environment, allowing usage of custom versions of JSDOM ([#14717](https://github.com/jestjs/jest/pull/14717))

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

@@ -1,5 +1,12 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`--listTests flag --outputFile flag causes tests to be saved in the file as JSON 1`] = `"["/MOCK_ABSOLUTE_PATH/e2e/list-tests/__tests__/dummy.test.js","/MOCK_ABSOLUTE_PATH/e2e/list-tests/__tests__/other.test.js"]"`;
+
+exports[`--listTests flag --outputFile flag causes tests to be saved in the file in different lines 1`] = `
+"/MOCK_ABSOLUTE_PATH/e2e/list-tests/__tests__/dummy.test.js
+/MOCK_ABSOLUTE_PATH/e2e/list-tests/__tests__/other.test.js"
+`;
+
 exports[`--listTests flag causes tests to be printed in different lines 1`] = `
 "/MOCK_ABSOLUTE_PATH/e2e/list-tests/__tests__/dummy.test.js
 /MOCK_ABSOLUTE_PATH/e2e/list-tests/__tests__/other.test.js"

e2e/__tests__/listTests.test.ts

@@ -6,6 +6,7 @@
  */
 
 import * as path from 'path';
+import * as fs from 'graceful-fs';
 import runJest from '../runJest';
 
 const testRootDir = path.resolve(__dirname, '..', '..');
@@ -36,4 +37,51 @@ describe('--listTests flag', () => {
       JSON.stringify(JSON.parse(stdout).map(normalizePaths).sort()),
     ).toMatchSnapshot();
   });
+
+  describe('--outputFile flag', () => {
+    const outputFilePath = path.resolve('.', 'test-lists.json');
+    afterAll(() => {
+      fs.unlinkSync(outputFilePath);
+    });
+    it('causes tests to be saved in the file as JSON', () => {
+      const {exitCode, stdout} = runJest('list-tests', [
+        '--listTests',
+        '--json',
+        '--outputFile',
+        outputFilePath,
+      ]);
+
+      expect(exitCode).toBe(0);
+      expect(stdout).toBe('');
+
+      const outputFileExists = fs.existsSync(outputFilePath);
+      expect(outputFileExists).toBe(true);
+
+      const outputFileContent = fs.readFileSync(outputFilePath, 'utf8');
+      expect(() => JSON.parse(outputFileContent)).not.toThrow();
+      expect(
+        JSON.stringify(
+          JSON.parse(outputFileContent).map(normalizePaths).sort(),
+        ),
+      ).toMatchSnapshot();
+    });
+    it('causes tests to be saved in the file in different lines', () => {
+      const {exitCode, stdout} = runJest('list-tests', [
+        '--listTests',
+        '--outputFile',
+        outputFilePath,
+      ]);
+
+      expect(exitCode).toBe(0);
+      expect(stdout).toBe('');
+
+      const outputFileExists = fs.existsSync(outputFilePath);
+      expect(outputFileExists).toBe(true);
+
+      const outputFileContent = fs.readFileSync(outputFilePath, 'utf8');
+      expect(
+        normalizePaths(outputFileContent).split('\n').sort().join('\n'),
+      ).toMatchSnapshot();
+    });
+  });
 });

packages/jest-core/src/runJest.ts

@@ -214,13 +214,21 @@ export default async function runJest({
 
   if (globalConfig.listTests) {
     const testsPaths = [...new Set(allTests.map(test => test.path))];
-    /* eslint-disable no-console */
+    let testsListOutput;
+
     if (globalConfig.json) {
-      console.log(JSON.stringify(testsPaths));
+      testsListOutput = JSON.stringify(testsPaths);
+    } else {
+      testsListOutput = testsPaths.join('\n');
+    }
+
+    if (globalConfig.outputFile) {
+      const outputFile = path.resolve(process.cwd(), globalConfig.outputFile);
+      fs.writeFileSync(outputFile, testsListOutput, 'utf8');
     } else {
-      console.log(testsPaths.join('\n'));
+      // eslint-disable-next-line no-console
+      console.log(testsListOutput);
     }
-    /* eslint-enable */
 
     onComplete && onComplete(makeEmptyAggregatedTestResult());
     return;