add message

e2e/__tests__/runProjects.test.ts

@@ -7,54 +7,82 @@
 
 import {resolve} from 'path';
 
-import {json as runWithJson} from '../runJest';
+import {RunJestJsonResult, json as runWithJson} from '../runJest';
 
 const dir = resolve(__dirname, '..', 'run-projects');
 
-test('run first project when runProjects is [first-project]', () => {
-  const {json} = runWithJson('run-projects', [
-    `--runProjects`,
-    'first-project',
-  ]);
-  expect(json.success).toBe(true);
-  expect(json.numTotalTests).toBe(1);
-  expect(json.testResults.map(({name}) => name)).toEqual([
-    resolve(dir, '__tests__/first-project.test.js'),
-  ]);
+describe('when Jest is started with `--runProjects first-project`', () => {
+  let result: RunJestJsonResult;
+  beforeAll(() => {
+    result = runWithJson('run-projects', [`--runProjects`, 'first-project']);
+  });
+  it('runs the tests in the first project only', () => {
+    expect(result.json.success).toBe(true);
+    expect(result.json.numTotalTests).toBe(1);
+    expect(result.json.testResults.map(({name}) => name)).toEqual([
+      resolve(dir, '__tests__/first-project.test.js'),
+    ]);
+  });
+  it('prints that only first-project will run', () => {
+    expect(result.stderr).toMatch(/^Will run one project: first-project/);
+  });
 });
 
-test('run second project when runProjects is [second-project]', () => {
-  const {json} = runWithJson('run-projects', [
-    '--runProjects',
-    'second-project',
-  ]);
-  expect(json.success).toBe(true);
-  expect(json.numTotalTests).toBe(1);
-  expect(json.testResults.map(({name}) => name)).toEqual([
-    resolve(dir, '__tests__/second-project.test.js'),
-  ]);
+describe('when Jest is started with `--runProjects second-project`', () => {
+  let result: RunJestJsonResult;
+  beforeAll(() => {
+    result = runWithJson('run-projects', [`--runProjects`, 'second-project']);
+  });
+  it('runs the tests in the second project only', () => {
+    expect(result.json.success).toBe(true);
+    expect(result.json.numTotalTests).toBe(1);
+    expect(result.json.testResults.map(({name}) => name)).toEqual([
+      resolve(dir, '__tests__/second-project.test.js'),
+    ]);
+  });
+  it('prints that only second-project will run', () => {
+    expect(result.stderr).toMatch(/^Will run one project: second-project/);
+  });
 });
 
-test('run first and second project when runProjects is [first-project, second-project]', () => {
-  const {json} = runWithJson('run-projects', [
-    '--runProjects',
-    'first-project',
-    'second-project',
-  ]);
-  expect(json.success).toBe(true);
-  expect(json.numTotalTests).toBe(2);
-  expect(json.testResults.map(({name}) => name).sort()).toEqual([
-    resolve(dir, '__tests__/first-project.test.js'),
-    resolve(dir, '__tests__/second-project.test.js'),
-  ]);
+describe('when Jest is started with `--runProjects first-project second-project`', () => {
+  let result: RunJestJsonResult;
+  beforeAll(() => {
+    result = runWithJson('run-projects', [
+      `--runProjects`,
+      'first-project',
+      'second-project',
+    ]);
+  });
+  it('runs the tests in the first and second projects', () => {
+    expect(result.json.success).toBe(true);
+    expect(result.json.numTotalTests).toBe(2);
+    expect(result.json.testResults.map(({name}) => name).sort()).toEqual([
+      resolve(dir, '__tests__/first-project.test.js'),
+      resolve(dir, '__tests__/second-project.test.js'),
+    ]);
+  });
+  it('prints that both first-project and second-project will run', () => {
+    expect(result.stderr).toMatch(
+      /^Will run 2 projects:\n- first-project\n- second-project/,
+    );
+  });
 });
 
-test('run first and second project when runProjects is not specified', () => {
-  const {json} = runWithJson('run-projects', []);
-  expect(json.success).toBe(true);
-  expect(json.numTotalTests).toBe(2);
-  expect(json.testResults.map(({name}) => name).sort()).toEqual([
-    resolve(dir, '__tests__/first-project.test.js'),
-    resolve(dir, '__tests__/second-project.test.js'),
-  ]);
+describe('when Jest is started without providing `--runProjects`', () => {
+  let result: RunJestJsonResult;
+  beforeAll(() => {
+    result = runWithJson('run-projects', []);
+  });
+  it('runs the tests in the first and second projects', () => {
+    expect(result.json.success).toBe(true);
+    expect(result.json.numTotalTests).toBe(2);
+    expect(result.json.testResults.map(({name}) => name).sort()).toEqual([
+      resolve(dir, '__tests__/first-project.test.js'),
+      resolve(dir, '__tests__/second-project.test.js'),
+    ]);
+  });
+  it('does not print which projects are run', () => {
+    expect(result.stderr).not.toMatch(/^Will run/);
+  });
 });

packages/jest-core/src/cli/index.ts

@@ -19,14 +19,15 @@ import exit = require('exit');
 import {Filter} from '../types';
 import createContext from '../lib/create_context';
 import getChangedFilesPromise from '../getChangedFilesPromise';
-import getConfigsOfProjectsToRun from '../getConfigsOfProjectsToRun';
 import {formatHandleErrors} from '../collectHandles';
 import handleDeprecationWarnings from '../lib/handle_deprecation_warnings';
 import runJest from '../runJest';
 import TestWatcher from '../TestWatcher';
 import watch from '../watch';
 import pluralize from '../pluralize';
 import logDebugMessages from '../lib/log_debug_messages';
+import getConfigsOfProjectsToRun from '../getConfigsOfProjectsToRun';
+import getProjectsRunningMessage from '../getProjectsRunningMessage';
 
 const {print: preRunMessagePrint} = preRunMessage;
 
@@ -74,6 +75,10 @@ export const runCLI = async (
   }
 
   const configsOfProjectsToRun = getConfigsOfProjectsToRun(argv, configs);
+  if (argv.runProjects) {
+    const projectNames = configsOfProjectsToRun.map(config => config.name);
+    outputStream.write(getProjectsRunningMessage(projectNames) + '\n');
+  }
 
   await _run(
     globalConfig,

packages/jest-core/src/getProjectsRunningMessage.ts

@@ -0,0 +1,23 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+export default function getProjectsRunningMessage(
+  projectNames: Array<string>,
+): string {
+  if (projectNames.length === 0) {
+    return 'No project to run';
+  }
+  if (projectNames.length === 1) {
+    return `Will run one project: ${projectNames[0]}`;
+  }
+  const projectsList = projectNames.map(getListElement).join('\n');
+  return `Will run ${projectNames.length} projects:\n` + projectsList;
+}
+
+function getListElement(content: string): string {
+  return `- ${content}`;
+}