feat(jest-config): Throw an error instead of showing a warning if multiple configs are used

CHANGELOG.md

@@ -11,6 +11,7 @@
 - `[jest-config, @jest/types]` Add `ci` to `GlobalConfig` ([#12378](https://github.com/facebook/jest/pull/12378))
 - `[jest-config]` [**BREAKING**] Rename `moduleLoader` to `runtime` ([#10817](https://github.com/facebook/jest/pull/10817))
 - `[jest-config]` [**BREAKING**] Rename `extraGlobals` to `sandboxInjectedGlobals` ([#10817](https://github.com/facebook/jest/pull/10817))
+- `[jest-config]` [**BREAKING**] Throw an error instead of showing a warning if multiple configs are used ([#12510](https://github.com/facebook/jest/pull/12510))
 - `[jest-core]` Pass project config to `globalSetup`/`globalTeardown` function as second argument ([#12440](https://github.com/facebook/jest/pull/12440))
 - `[jest-environment-jsdom]` [**BREAKING**] Upgrade jsdom to 19.0.0 ([#12290](https://github.com/facebook/jest/pull/12290))
 - `[jest-environment-jsdom]` [**BREAKING**] Add default `browser` condition to `exportConditions` for `jsdom` environment ([#11924](https://github.com/facebook/jest/pull/11924))

e2e/__tests__/__snapshots__/multipleConfigs.ts.snap

@@ -1,7 +1,8 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`multiple configs will warn 1`] = `
+exports[`multiple configs will throw error 1`] = `
 "● Multiple configurations found:
+
     * <rootDir>/e2e/multiple-configs/jest.config.js
     * <rootDir>/e2e/multiple-configs/jest.config.json
     * \`jest\` key in <rootDir>/e2e/multiple-configs/package.json
@@ -10,16 +11,6 @@ exports[`multiple configs will warn 1`] = `
   Either remove unused config files or select one explicitly with \`--config\`.
 
   Configuration Documentation:
-  https://jestjs.io/docs/configuration.html
-
-PASS Config from js file __tests__/test.js
-  ✓ dummy test"
-`;
-
-exports[`multiple configs will warn 2`] = `
-"Test Suites: 1 passed, 1 total
-Tests:       1 passed, 1 total
-Snapshots:   0 total
-Time:        <<REPLACED>>
-Ran all test suites."
+  https://jestjs.io/docs/configuration
+"
 `;

e2e/__tests__/multipleConfigs.ts

@@ -7,36 +7,30 @@
 
 import * as path from 'path';
 import slash = require('slash');
-import {extractSummary} from '../Utils';
 import runJest from '../runJest';
 
 const MULTIPLE_CONFIGS_WARNING_TEXT = 'Multiple configurations found';
 
-test('multiple configs will warn', () => {
+test('multiple configs will throw error', () => {
   const rootDir = slash(path.resolve(__dirname, '../..'));
   const {exitCode, stderr} = runJest('multiple-configs', [], {
     skipPkgJsonCheck: true,
   });
 
-  expect(exitCode).toBe(0);
+  expect(exitCode).toBe(1);
   expect(stderr).toContain(MULTIPLE_CONFIGS_WARNING_TEXT);
 
   const cleanStdErr = stderr.replace(new RegExp(rootDir, 'g'), '<rootDir>');
-  const {rest, summary} = extractSummary(cleanStdErr);
-
-  expect(rest).toMatchSnapshot();
-  expect(summary).toMatchSnapshot();
+  expect(cleanStdErr).toMatchSnapshot();
 });
 
-test('multiple configs warning can be suppressed by using --config', () => {
-  const {exitCode, stderr} = runJest(
+test('multiple configs error can be suppressed by using --config', () => {
+  const {exitCode} = runJest(
     'multiple-configs',
     ['--config', 'jest.config.json'],
     {
       skipPkgJsonCheck: true,
     },
   );
-
   expect(exitCode).toBe(0);
-  expect(stderr).not.toContain(MULTIPLE_CONFIGS_WARNING_TEXT);
 });

packages/jest-config/src/__tests__/resolveConfigPath.test.ts

@@ -16,16 +16,6 @@ const ERROR_PATTERN = /Could not find a config file based on provided values/;
 const NO_ROOT_DIR_ERROR_PATTERN = /Can't find a root directory/;
 const MULTIPLE_CONFIGS_ERROR_PATTERN = /Multiple configurations found/;
 
-const mockConsoleWarn = () => {
-  jest.spyOn(console, 'warn');
-  const mockedConsoleWarn = console.warn as jest.Mock<void, Array<any>>;
-
-  // We will mock console.warn because it would produce a lot of noise in the tests
-  mockedConsoleWarn.mockImplementation(() => {});
-
-  return mockedConsoleWarn;
-};
-
 beforeEach(() => cleanup(DIR));
 afterEach(() => cleanup(DIR));
 
@@ -56,8 +46,6 @@ describe.each(JEST_CONFIG_EXT_ORDER.slice(0))(
     });
 
     test(`directory path with "${extension}"`, () => {
-      const mockedConsoleWarn = mockConsoleWarn();
-
       const relativePackageJsonPath = 'a/b/c/package.json';
       const absolutePackageJsonPath = path.resolve(
         DIR,
@@ -81,7 +69,6 @@ describe.each(JEST_CONFIG_EXT_ORDER.slice(0))(
 
       writeFiles(DIR, {[relativePackageJsonPath]: ''});
 
-      mockedConsoleWarn.mockClear();
       // absolute
       expect(
         resolveConfigPath(path.dirname(absolutePackageJsonPath), DIR),
@@ -91,12 +78,10 @@ describe.each(JEST_CONFIG_EXT_ORDER.slice(0))(
       expect(
         resolveConfigPath(path.dirname(relativePackageJsonPath), DIR),
       ).toBe(absolutePackageJsonPath);
-      expect(mockedConsoleWarn).not.toBeCalled();
 
       // jest.config.js takes precedence
       writeFiles(DIR, {[relativeJestConfigPath]: ''});
 
-      mockedConsoleWarn.mockClear();
       // absolute
       expect(
         resolveConfigPath(path.dirname(absolutePackageJsonPath), DIR),
@@ -106,30 +91,19 @@ describe.each(JEST_CONFIG_EXT_ORDER.slice(0))(
       expect(
         resolveConfigPath(path.dirname(relativePackageJsonPath), DIR),
       ).toBe(absoluteJestConfigPath);
-      expect(mockedConsoleWarn).not.toBeCalled();
 
       // jest.config.js and package.json with 'jest' cannot be used together
       writeFiles(DIR, {[relativePackageJsonPath]: JSON.stringify({jest: {}})});
 
       // absolute
-      mockedConsoleWarn.mockClear();
-      expect(
+      expect(() =>
         resolveConfigPath(path.dirname(absolutePackageJsonPath), DIR),
-      ).toBe(absoluteJestConfigPath);
-      expect(mockedConsoleWarn).toBeCalledTimes(1);
-      expect(mockedConsoleWarn.mock.calls[0].join()).toMatch(
-        MULTIPLE_CONFIGS_ERROR_PATTERN,
-      );
+      ).toThrowError(MULTIPLE_CONFIGS_ERROR_PATTERN);
 
       // relative
-      mockedConsoleWarn.mockClear();
-      expect(
+      expect(() =>
         resolveConfigPath(path.dirname(relativePackageJsonPath), DIR),
-      ).toBe(absoluteJestConfigPath);
-      expect(mockedConsoleWarn).toBeCalledTimes(1);
-      expect(mockedConsoleWarn.mock.calls[0].join()).toMatch(
-        MULTIPLE_CONFIGS_ERROR_PATTERN,
-      );
+      ).toThrowError(MULTIPLE_CONFIGS_ERROR_PATTERN);
 
       expect(() => {
         resolveConfigPath(
@@ -146,8 +120,7 @@ const pickPairsWithSameOrder = <T>(array: ReadonlyArray<T>) =>
     .map((value1, idx, arr) =>
       arr.slice(idx + 1).map(value2 => [value1, value2]),
     )
-    // TODO: use .flat() when we drop Node 10
-    .reduce((acc, val) => acc.concat(val), []);
+    .flat();
 
 test('pickPairsWithSameOrder', () => {
   expect(pickPairsWithSameOrder([1, 2, 3])).toStrictEqual([
@@ -158,11 +131,9 @@ test('pickPairsWithSameOrder', () => {
 });
 
 describe.each(pickPairsWithSameOrder(JEST_CONFIG_EXT_ORDER))(
-  'Using multiple configs shows warning',
+  'Using multiple configs shows error',
   (extension1, extension2) => {
-    test(`Using jest.config${extension1} and jest.config${extension2} shows warning`, () => {
-      const mockedConsoleWarn = mockConsoleWarn();
-
+    test(`Using jest.config${extension1} and jest.config${extension2} shows error`, () => {
       const relativeJestConfigPaths = [
         `a/b/c/jest.config${extension1}`,
         `a/b/c/jest.config${extension2}`,
@@ -173,15 +144,9 @@ describe.each(pickPairsWithSameOrder(JEST_CONFIG_EXT_ORDER))(
         [relativeJestConfigPaths[1]]: '',
       });
 
-      // multiple configs here, should print warning
-      mockedConsoleWarn.mockClear();
-      expect(
+      expect(() =>
         resolveConfigPath(path.dirname(relativeJestConfigPaths[0]), DIR),
-      ).toBe(path.resolve(DIR, relativeJestConfigPaths[0]));
-      expect(mockedConsoleWarn).toBeCalledTimes(1);
-      expect(mockedConsoleWarn.mock.calls[0].join()).toMatch(
-        MULTIPLE_CONFIGS_ERROR_PATTERN,
-      );
+      ).toThrowError(MULTIPLE_CONFIGS_ERROR_PATTERN);
     });
   },
 );

packages/jest-config/src/index.ts

@@ -41,7 +41,7 @@ export async function readConfig(
   skipArgvConfigOption?: boolean,
   parentConfigDirname?: string | null,
   projectIndex = Infinity,
-  skipMultipleConfigWarning = false,
+  skipMultipleConfigError = false,
 ): Promise<ReadConfig> {
   let rawOptions: Config.InitialOptions;
   let configPath = null;
@@ -78,15 +78,15 @@ export async function readConfig(
     configPath = resolveConfigPath(
       argv.config,
       process.cwd(),
-      skipMultipleConfigWarning,
+      skipMultipleConfigError,
     );
     rawOptions = await readConfigFileAndSetRootDir(configPath);
   } else {
     // Otherwise just try to find config in the current rootDir.
     configPath = resolveConfigPath(
       packageRootOrConfig,
       process.cwd(),
-      skipMultipleConfigWarning,
+      skipMultipleConfigError,
     );
     rawOptions = await readConfigFileAndSetRootDir(configPath);
   }

packages/jest-config/src/resolveConfigPath.ts

@@ -9,11 +9,13 @@ import * as path from 'path';
 import chalk = require('chalk');
 import * as fs from 'graceful-fs';
 import slash = require('slash');
+import {ValidationError} from 'jest-validate';
 import {
   JEST_CONFIG_BASE_NAME,
   JEST_CONFIG_EXT_ORDER,
   PACKAGE_JSON,
 } from './constants';
+import {BULLET, DOCUMENTATION_NOTE} from './utils';
 
 const isFile = (filePath: string) =>
   fs.existsSync(filePath) && !fs.lstatSync(filePath).isDirectory();
@@ -23,7 +25,7 @@ const getConfigFilename = (ext: string) => JEST_CONFIG_BASE_NAME + ext;
 export default function resolveConfigPath(
   pathToResolve: string,
   cwd: string,
-  skipMultipleConfigWarning = false,
+  skipMultipleConfigError = false,
 ): string {
   if (!path.isAbsolute(cwd)) {
     throw new Error(`"cwd" must be an absolute path. cwd: ${cwd}`);
@@ -58,15 +60,15 @@ export default function resolveConfigPath(
     absolutePath,
     pathToResolve,
     cwd,
-    skipMultipleConfigWarning,
+    skipMultipleConfigError,
   );
 }
 
 const resolveConfigPathByTraversing = (
   pathToResolve: string,
   initialPath: string,
   cwd: string,
-  skipMultipleConfigWarning: boolean,
+  skipMultipleConfigError: boolean,
 ): string => {
   const configFiles = JEST_CONFIG_EXT_ORDER.map(ext =>
     path.resolve(pathToResolve, getConfigFilename(ext)),
@@ -77,8 +79,8 @@ const resolveConfigPathByTraversing = (
     configFiles.push(packageJson);
   }
 
-  if (!skipMultipleConfigWarning && configFiles.length > 1) {
-    console.warn(makeMultipleConfigsWarning(configFiles));
+  if (!skipMultipleConfigError && configFiles.length > 1) {
+    throw new ValidationError(...makeMultipleConfigsErrorMessage(configFiles));
   }
 
   if (configFiles.length > 0 || packageJson) {
@@ -96,7 +98,7 @@ const resolveConfigPathByTraversing = (
     path.dirname(pathToResolve),
     initialPath,
     cwd,
-    skipMultipleConfigWarning,
+    skipMultipleConfigError,
   );
 };
 
@@ -137,20 +139,18 @@ function extraIfPackageJson(configPath: string) {
   return '';
 }
 
-const makeMultipleConfigsWarning = (configPaths: Array<string>) =>
-  chalk.yellow(
-    [
-      chalk.bold('\u25cf Multiple configurations found:'),
-      ...configPaths.map(
-        configPath =>
-          `    * ${extraIfPackageJson(configPath)}${slash(configPath)}`,
-      ),
-      '',
-      '  Implicit config resolution does not allow multiple configuration files.',
-      '  Either remove unused config files or select one explicitly with `--config`.',
-      '',
-      '  Configuration Documentation:',
-      '  https://jestjs.io/docs/configuration.html',
-      '',
-    ].join('\n'),
-  );
+const makeMultipleConfigsErrorMessage = (
+  configPaths: Array<string>,
+): [string, string, string] => [
+  `${BULLET}${chalk.bold('Multiple configurations found')}`,
+  [
+    ...configPaths.map(
+      configPath =>
+        `    * ${extraIfPackageJson(configPath)}${slash(configPath)}`,
+    ),
+    '',
+    '  Implicit config resolution does not allow multiple configuration files.',
+    '  Either remove unused config files or select one explicitly with `--config`.',
+  ].join('\n'),
+  DOCUMENTATION_NOTE,
+];