add init option

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## master
 
+### Features
+
+- `[jest-cli]` Add `jest --init` option that generates a basic configuration file with a short description for each option ([#6442](https://github.com/facebook/jest/pull/6442))
+
 ### Fixes
 
 - `[jest-config]` Add missing options to the `defaults` object ([#6428](https://github.com/facebook/jest/pull/6428))

docs/CLI.md

@@ -169,6 +169,10 @@ Force Jest to exit after all tests have completed running. This is useful when r
 
 Show the help information, similar to this page.
 
+### `--init`
+
+Generate a basic configuration file. Based on your project, Jest will ask you a few questions that will help to generate a `jest.config.js` file with a short description for each option.
+
 ### `--json`
 
 Prints the test results in JSON. This mode will send all other test output and user messages to stderr.

docs/GettingStarted.md

@@ -69,6 +69,14 @@ If you'd like to learn more about running `jest` through the command line, take
 
 ## Additional Configuration
 
+### Generate a basic configuration file
+
+Based on your project, Jest will ask you a few questions and will create a basic configuration file with a short description for each option:
+
+```bash
+jest --init
+```
+
 ### Using Babel
 
 To use [Babel](http://babeljs.io/), install the `babel-jest` and `regenerator-runtime` packages:

package.json

@@ -147,6 +147,7 @@
       "/packages/.*/src/__tests__/expect_util.js",
       "/packages/jest-cli/src/__tests__/test_root",
       "/packages/jest-cli/src/__tests__/__fixtures__/",
+      "/packages/jest-cli/src/lib/__tests__/fixtures/",
       "/packages/jest-haste-map/src/__tests__/haste_impl.js",
       "/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/",
       "/packages/jest-runtime/src/__tests__/defaultResolver.js",

packages/jest-cli/package.json

@@ -32,6 +32,7 @@
     "jest-worker": "^23.0.1",
     "micromatch": "^2.3.11",
     "node-notifier": "^5.2.1",
+    "prompts": "^0.1.9",
     "realpath-native": "^1.0.0",
     "rimraf": "^2.5.4",
     "slash": "^1.0.0",

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

@@ -294,6 +294,10 @@ export const options = {
       'A JSON string with map of variables for the haste module system',
     type: 'string',
   },
+  init: {
+    description: 'Generate a basic configuration file',
+    type: 'boolean',
+  },
   json: {
     default: undefined,
     description:

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

@@ -32,10 +32,17 @@ import pluralize from '../pluralize';
 import yargs from 'yargs';
 import rimraf from 'rimraf';
 import {sync as realpath} from 'realpath-native';
+import init from '../lib/init';
 
 export async function run(maybeArgv?: Argv, project?: Path) {
   try {
     const argv: Argv = buildArgv(maybeArgv, project);
+
+    if (argv.init) {
+      await init();
+      return;
+    }
+
     const projects = getProjectListFromCLIArgs(argv, project);
 
     const {results, globalConfig} = await runCLI(argv, projects);

packages/jest-cli/src/constants.js

@@ -16,3 +16,5 @@ export const ICONS = {
   pending: '\u25CB',
   success: isWindows ? '\u221A' : '\u2713',
 };
+export const PACKAGE_JSON = 'package.json';
+export const JEST_CONFIG = 'jest.config.js';

packages/jest-cli/src/lib/__tests__/__snapshots__/init.test.js.snap

@@ -0,0 +1,252 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`init has jest config in package.json should ask the user whether to override config or not 1`] = `
+Object {
+  "initial": true,
+  "message": "It seems that you already have a jest configuration, do you want to override it?",
+  "name": "continue",
+  "type": "confirm",
+}
+`;
+
+exports[`init has-jest-config-file ask the user whether to override config or not user answered with "Yes" 1`] = `
+Object {
+  "initial": true,
+  "message": "It seems that you already have a jest configuration, do you want to override it?",
+  "name": "continue",
+  "type": "confirm",
+}
+`;
+
+exports[`init project with package.json and no jest config all questions answered with answer: "No" should return the default configuration (an empty config) 1`] = `
+"// For a detailed explanation regarding each configuration property, visit:
+// https://facebook.github.io/jest/docs/en/configuration.html
+
+module.exports = {
+  // All imported modules in your tests should be mocked automatically
+  // automock: false,
+
+  // Stop running tests after the first failure
+  // bail: false,
+
+  // Respect \\"browser\\" field in package.json when resolving modules
+  // browser: false,
+
+  // The directory where Jest should store its cached dependency information
+  // cacheDirectory: \\"/tmp/jest\\",
+
+  // Automatically clear mock calls and instances between every test
+  // clearMocks: false,
+
+  // Indicates whether the coverage information should be collected while executing the test
+  // collectCoverage: false,
+
+  // An array of glob patterns indicating a set of files for which coverage information should be collected
+  // collectCoverageFrom: null,
+
+  // The directory where Jest should output its coverage files
+  // coverageDirectory: null,
+
+  // An array of regexp pattern strings used to skip coverage collection
+  // coveragePathIgnorePatterns: [
+  //   \\"/node_modules/\\"
+  // ],
+
+  // A list of reporter names that Jest uses when writing coverage reports
+  // coverageReporters: [
+  //   \\"json\\",
+  //   \\"text\\",
+  //   \\"lcov\\",
+  //   \\"clover\\"
+  // ],
+
+  // An object that configures minimum threshold enforcement for coverage results
+  // coverageThreshold: null,
+
+  // Make calling deprecated APIs throw helpful error messages
+  // errorOnDeprecated: false,
+
+  // Force coverage collection from ignored files usin a array of glob patterns
+  // forceCoverageMatch: [],
+
+  // A path to a module which exports an async function that is triggered once before all test suites
+  // globalSetup: null,
+
+  // A path to a module which exports an async function that is triggered once after all test suites
+  // globalTeardown: null,
+
+  // A set of global variables that need to be available in all test environments
+  // globals: {},
+
+  // An array of directory names to be searched recursively up from the requiring module's location
+  // moduleDirectories: [
+  //   \\"node_modules\\"
+  // ],
+
+  // An array of file extensions your modules use
+  // moduleFileExtensions: [
+  //   \\"js\\",
+  //   \\"json\\",
+  //   \\"jsx\\",
+  //   \\"node\\"
+  // ],
+
+  // A map from regular expressions to module names that allow to stub out resources with a single module
+  // moduleNameMapper: {},
+
+  // An array of regexp pattern strings, matched against all module paths before considered 'visible' to the module loader
+  // modulePathIgnorePatterns: [],
+
+  // Activates notifications for test results
+  // notify: false,
+
+  // An enum that specifies notification mode. Requires { notify: true }
+  // notifyMode: \\"always\\",
+
+  // A preset that is used as a base for Jest's configuration
+  // preset: null,
+
+  // Run tests from one or more projects
+  // projects: null,
+
+  // Use this configuration option to add custom reporters to Jest
+  // reporters: undefined,
+
+  // Automatically reset mock state between every test
+  // resetMocks: false,
+
+  // Reset the module registry before running each individual test
+  // resetModules: false,
+
+  // A path to a custom resolver
+  // resolver: null,
+
+  // Automatically restore mock state between every test
+  // restoreMocks: false,
+
+  // The root directory that Jest should scan for tests and modules within
+  // rootDir: null,
+
+  // A list of paths to directories that Jest should use to search for files in
+  // roots: [
+  //   \\"<rootDir>\\"
+  // ],
+
+  // Allows you to use a custom runner instead of Jest's default test runner
+  // runner: \\"jest-runner\\",
+
+  // The paths to modules that run some code to configure or set up the testing environment before each test
+  // setupFiles: [],
+
+  // The path to a module that runs some code to configure or set up the testing framework before each test
+  // setupTestFrameworkScriptFile: null,
+
+  // A list of paths to snapshot serializer modules Jest should use for snapshot testing
+  // snapshotSerializers: [],
+
+  // The test environment that will be used for testing
+  // testEnvironment: \\"jest-environment-jsdom\\",
+
+  // Options that will be passed to the testEnvironment
+  // testEnvironmentOptions: {},
+
+  // Adds a location field to test results
+  // testLocationInResults: false,
+
+  // The glob patterns Jest uses to detect test files
+  // testMatch: [
+  //   \\"**/__tests__/**/*.js?(x)\\",
+  //   \\"**/?(*.)+(spec|test).js?(x)\\"
+  // ],
+
+  // An array of regexp pattern strings that are matched against all test paths, matched tests are skipped
+  // testPathIgnorePatterns: [
+  //   \\"/node_modules/\\"
+  // ],
+
+  // The regexp pattern Jest uses to detect test files
+  // testRegex: \\"\\",
+
+  // This option allows the use of a custom results processor
+  // testResultsProcessor: null,
+
+  // This option allows use of a custom test runner
+  // testRunner: \\"jasmine2\\",
+
+  // This option sets the URL for the jsdom environment. It is reflected in properties such as location.href
+  // testURL: \\"about:blank\\",
+
+  // Setting this value to \\"fake\\" allows the use of fake timers for functions such as \\"setTimeout\\"
+  // timers: \\"real\\",
+
+  // A map from regular expressions to paths to transformers
+  // transform: null,
+
+  // An array of regexp pattern strings that are matched against all source file paths, matched files will skip transformation
+  // transformIgnorePatterns: [
+  //   \\"/node_modules/\\"
+  // ],
+
+  // An array of regexp pattern strings that are matched against all modules before the module loader will automatically return a mock for them
+  // unmockedModulePathPatterns: undefined,
+
+  // Indicates whether each individual test should be reported during the run
+  // verbose: null,
+
+  // An array of regexp patterns that are matched against all source file paths before re-running tests in watch mode
+  // watchPathIgnorePatterns: [],
+
+  // Whether to use watchman for file crawling
+  // watchman: true,
+};
+"
+`;
+
+exports[`init project with package.json and no jest config some questions answered with answer: "Yes" should create package.json with configured test command when {scripts: true} 1`] = `
+"{
+  \\"name\\": \\"only_package_json\\",
+  \\"scripts\\": {
+    \\"test\\": \\"jest\\"
+  }
+}
+"
+`;
+
+exports[`init typescript project should ask "typescript question" when has typescript in dependencies 1`] = `
+Object {
+  "initial": true,
+  "message": "Typescript detected, would you like to setup Jest for Typescript?",
+  "name": "typescript",
+  "type": "confirm",
+}
+`;
+
+exports[`init typescript project should ask "typescript question" when has typescript in devDependencies 1`] = `
+Object {
+  "initial": true,
+  "message": "Typescript detected, would you like to setup Jest for Typescript?",
+  "name": "typescript",
+  "type": "confirm",
+}
+`;
+
+exports[`init typescript project should create configuration for {typescript: true} 1`] = `
+Object {
+  "globals": Object {
+    "ts-jest": Object {
+      "tsConfigFile": "tsconfig.json",
+    },
+  },
+  "moduleFileExtensions": Array [
+    "ts",
+    "tsx",
+    "js",
+  ],
+  "testMatch": Array [
+    "**/__tests__/*.+(ts|tsx|js)",
+  ],
+  "transform": Object {
+    "^.+\\\\.(ts|tsx)$": "ts-jest",
+  },
+}
+`;

packages/jest-cli/src/lib/__tests__/__snapshots__/modify_package_json.test.js.snap

@@ -0,0 +1,34 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`should add test script when there are no scripts 1`] = `
+"{
+  \\"scripts\\": {
+    \\"test\\": \\"jest\\"
+  }
+}
+"
+`;
+
+exports[`should add test script when there are scripts 1`] = `
+"{
+  \\"scripts\\": {
+    \\"lint\\": \\"eslint .\\",
+    \\"test\\": \\"jest\\"
+  }
+}
+"
+`;
+
+exports[`should not add test script when { shouldModifyScripts: false } 1`] = `
+"{}
+"
+`;
+
+exports[`should remove jest config if exists 1`] = `
+"{
+  \\"scripts\\": {
+    \\"test\\": \\"jest\\"
+  }
+}
+"
+`;

packages/jest-cli/src/lib/__tests__/fixtures/has_jest_config_file/jest.config.js

@@ -0,0 +1 @@
+module.exports = {};

packages/jest-cli/src/lib/__tests__/fixtures/has_jest_config_file/package.json

@@ -0,0 +1 @@
+{}

packages/jest-cli/src/lib/__tests__/fixtures/has_jest_config_in_package_json/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "has_jest_config_in_package_json",
+  "jest": {
+    "coverage": true
+  }
+}

packages/jest-cli/src/lib/__tests__/fixtures/only_package_json/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "only_package_json",
+  "scripts": {
+    "test": "different-test-runner"
+  }
+}

packages/jest-cli/src/lib/__tests__/fixtures/test_script_configured/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "test_script_configured",
+  "scripts": {
+    "test": "jest"
+  }
+}