feat: warn when there are multiple configs (#11922)

Author: jankaifer

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ### Features
 
+- `[jest-config]` Warn when multiple Jest configs are located ([#11922](https://github.com/facebook/jest/pull/11922))
+
 ### Fixes
 
 - `[expect]` Pass matcher context to asymmetric matchers ([#11926](https://github.com/facebook/jest/pull/11926) & [#11930](https://github.com/facebook/jest/pull/11930))

e2e/Utils.ts

@@ -176,20 +176,23 @@ interface JestPackageJson extends PackageJson {
 }
 
 const DEFAULT_PACKAGE_JSON: JestPackageJson = {
-  description: 'THIS IS AN AUTOGENERATED FILE AND SHOULD NOT BE ADDED TO GIT',
   jest: {
     testEnvironment: 'node',
   },
 };
 
 export const createEmptyPackage = (
   directory: Config.Path,
-  packageJson = DEFAULT_PACKAGE_JSON,
+  packageJson: PackageJson = DEFAULT_PACKAGE_JSON,
 ) => {
+  const packageJsonWithDefaults = {
+    ...packageJson,
+    description: 'THIS IS AN AUTOGENERATED FILE AND SHOULD NOT BE ADDED TO GIT',
+  };
   fs.mkdirSync(directory, {recursive: true});
   fs.writeFileSync(
     path.resolve(directory, 'package.json'),
-    JSON.stringify(packageJson, null, 2),
+    JSON.stringify(packageJsonWithDefaults, null, 2),
   );
 };
 

e2e/__tests__/__snapshots__/multipleConfigs.ts.snap

@@ -0,0 +1,25 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`multiple configs will warn 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
+
+  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
+
+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.
+`;

e2e/__tests__/configOverride.test.ts

@@ -0,0 +1,24 @@
+/**
+ * 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.
+ */
+
+import {getConfig} from '../runJest';
+
+test('reads config from cjs file', () => {
+  const {configs} = getConfig(
+    'config-override',
+    ['--config', 'different-config.json'],
+    {
+      skipPkgJsonCheck: true,
+    },
+  );
+
+  expect(configs).toHaveLength(1);
+  expect(configs[0].displayName).toEqual({
+    color: 'white',
+    name: 'Config from different-config.json file',
+  });
+});

e2e/__tests__/dependencyClash.test.ts

@@ -18,7 +18,7 @@ const hasteImplModulePath = path
 
 beforeEach(() => {
   cleanup(tempDir);
-  createEmptyPackage(tempDir);
+  createEmptyPackage(tempDir, {});
 });
 
 // This test case is checking that when having both

e2e/__tests__/multipleConfigs.ts

@@ -0,0 +1,43 @@
+/**
+ * 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.
+ */
+
+import * as path from 'path';
+import {wrap} from 'jest-snapshot-serializer-raw';
+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', () => {
+  const rootDir = slash(path.resolve(__dirname, '../..'));
+  const {exitCode, stderr} = runJest('multiple-configs', [], {
+    skipPkgJsonCheck: true,
+  });
+
+  expect(exitCode).toBe(0);
+  expect(stderr).toContain(MULTIPLE_CONFIGS_WARNING_TEXT);
+
+  const cleanStdErr = stderr.replace(new RegExp(rootDir, 'g'), '<rootDir>');
+  const {rest, summary} = extractSummary(cleanStdErr);
+
+  expect(wrap(rest)).toMatchSnapshot();
+  expect(wrap(summary)).toMatchSnapshot();
+});
+
+test('multiple configs warning can be suppressed by using --config', () => {
+  const {exitCode, stderr} = runJest(
+    'multiple-configs',
+    ['--config', 'jest.config.json'],
+    {
+      skipPkgJsonCheck: true,
+    },
+  );
+
+  expect(exitCode).toBe(0);
+  expect(stderr).not.toContain(MULTIPLE_CONFIGS_WARNING_TEXT);
+});

e2e/config-override/__tests__/test.js

@@ -0,0 +1,10 @@
+/**
+ * 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.
+ */
+
+test('dummy test', () => {
+  expect(1).toBe(1);
+});

e2e/config-override/different-config.json

@@ -0,0 +1,3 @@
+{
+  "displayName": "Config from different-config.json file"
+}

e2e/config-override/jest.config.json

@@ -0,0 +1,3 @@
+{
+  "displayName": "Config from json file"
+}

e2e/config-override/package.json

@@ -0,0 +1,3 @@
+{
+  "name": "config-override"
+}