Add --listTests flag

docs/en/CLI.md

@@ -133,6 +133,10 @@ Write test results to a file when the `--json` option is also specified.
 
 Will run all tests affected by file changes in the last commit made.
 
+### `--listTests`
+
+Lists all tests Jest will run given the other arguments, and exits.
+
 ### `--logHeapUsage`
 
 Logs the heap usage after every test. Useful to debug memory leaks. Use together with `--runInBand` and `--expose-gc` in node.

integration_tests/__tests__/list_tests-test.js

@@ -0,0 +1,21 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @emails oncall+jsinfra
+ */
+'use strict';
+
+const runJest = require('../runJest');
+
+describe('--listTests flag', () => {
+ it('causes tests to be printed out as JSON', () => {
+ const {status, stdout} = runJest('list_tests', ['--listTests']);
+
+ expect(status).toBe(0);
+ expect(() => JSON.parse(stdout)).not.toThrow();
+ });
+});

integration_tests/list_tests/__tests__/dummy-test.js

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+'use strict';
+
+it("isn't actually run", () => {
+ // (because it is only used for --listTests)
+ expect(true).toBe(false);
+});

integration_tests/list_tests/package.json

@@ -0,0 +1,5 @@
+{
+ "jest": {
+ "testEnvironment": "node"
+ }
+}

packages/jest-cli/src/cli/args.js

@@ -196,6 +196,11 @@ const options = {
  'commit made.',
  type: 'boolean',
  },
+ listTests: {
+ default: false,
+ description: 'Lists all tests Jest will run given the arguments and exits.',
+ type: 'boolean',
+ },
  logHeapUsage: {
  default: undefined,
  description: 'Logs the heap usage after every test. Useful to debug ' +

packages/jest-cli/src/runJest.js

@@ -175,6 +175,14 @@ const runJest = async (
  );
 
  allTests = sequencer.sort(allTests);
+
+ // With --listTests, simply print the test info as JSON and exit.
+ if (globalConfig.listTests) {
+ const testsJson = JSON.stringify(allTests, null, ' ');
+ new Console(pipe, pipe).log(testsJson);
+ process.exit(0);
+ }
+
  if (!allTests.length) {
  new Console(pipe, pipe).log(getNoTestsFoundMessage(testRunData, pattern));
  } else if (

packages/jest-config/src/index.js

@@ -69,6 +69,7 @@ const getConfigs = (
  coverageThreshold: options.coverageThreshold,
  expand: options.expand,
  forceExit: options.forceExit,
+ listTests: options.listTests,
  logHeapUsage: options.logHeapUsage,
  mapCoverage: options.mapCoverage,
  noStackTrace: options.noStackTrace,

packages/jest-config/src/normalize.js

@@ -376,6 +376,7 @@ function normalize(options: InitialOptions, argv: Object = {}) {
  case 'coverageThreshold':
  case 'expand':
  case 'globals':
+ case 'listTests':
  case 'logHeapUsage':
  case 'mapCoverage':
  case 'moduleDirectories':

packages/jest-config/src/validConfig.js

@@ -43,6 +43,7 @@ module.exports = ({
  haste: {
  providesModuleNodeModules: ['react', 'react-native'],
  },
+ listTests: false,
  logHeapUsage: true,
  mapCoverage: false,
  moduleDirectories: ['node_modules'],

packages/jest-validate/src/__tests__/fixtures/jestConfig.js

@@ -85,6 +85,7 @@ const validConfig = {
  haste: {
  providesModuleNodeModules: ['react', 'react-native'],
  },
+ listTests: true,
  logHeapUsage: true,
  moduleDirectories: ['node_modules'],
  moduleFileExtensions: ['js', 'json', 'jsx', 'node'],

types/Config.js

@@ -134,6 +134,7 @@ export type GlobalConfig = {|
  coverageThreshold: {global: {[key: string]: number}},
  expand: boolean,
  forceExit: boolean,
+ listTests: boolean,
  logHeapUsage: boolean,
  mapCoverage: boolean,
  noStackTrace: boolean,