adds freezeCoreModules configuration option to mitigate memory leaks

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ### Features
 
+- `[jest-config]` Add `freezeCoreModules` configuration option to mitigate memory leaks described in the following issues: [#6399](https://github.com/facebook/jest/issues/6399), [#6814](https://github.com/facebook/jest/issues/6814) ([#8331](https://github.com/facebook/jest/pull/8331))
 - `[babel-plugin-jest-hoist]` Show codeframe on static hoisting issues ([#8865](https://github.com/facebook/jest/pull/8865))
 - `[babel-plugin-jest-hoist]` Add `BigInt` to `WHITELISTED_IDENTIFIERS` ([#8382](https://github.com/facebook/jest/pull/8382))
 - `[babel-preset-jest]` Add `@babel/plugin-syntax-bigint` ([#8382](https://github.com/facebook/jest/pull/8382))

TestUtils.ts

@@ -81,6 +81,8 @@ const DEFAULT_PROJECT_CONFIG: Config.ProjectConfig = {
   extraGlobals: [],
   filter: null,
   forceCoverageMatch: [],
+  freezeCoreModules: false,
+  freezeCoreModulesWhitelist: ['crypto'],
   globalSetup: null,
   globalTeardown: null,
   globals: {},
@@ -120,6 +122,7 @@ const DEFAULT_PROJECT_CONFIG: Config.ProjectConfig = {
   transform: [],
   transformIgnorePatterns: [],
   unmockedModulePathPatterns: null,
+  verbose: false,
   watchPathIgnorePatterns: [],
 };
 

docs/Configuration.md

@@ -367,6 +367,22 @@ You can collect coverage from those files with setting `forceCoverageMatch`.
 }
 ```
 
+### `freezeCoreModules` [boolean]
+
+Default: `false`
+
+Prevents overriding node's core module methods so to prevent memory leaks.
+
+Attempt to override such a property will fail silently.
+
+Running with [`verbose`](#verbose-boolean) flag will enable informative print outs.
+
+### `freezeCoreModulesWhitelist` [Array<string>]
+
+Default: `['crypto']`
+
+Array of node core modules which will not be frozen.
+
 ### `globals` [object]
 
 Default: `{}`

e2e/__tests__/__snapshots__/showConfig.test.ts.snap

@@ -19,6 +19,10 @@ exports[`--showConfig outputs config info and exits 1`] = `
       "errorOnDeprecated": false,
       "filter": null,
       "forceCoverageMatch": [],
+      "freezeCoreModules": false,
+      "freezeCoreModulesWhitelist": [
+        "crypto"
+      ],
       "globalSetup": null,
       "globalTeardown": null,
       "globals": {},
@@ -78,6 +82,7 @@ exports[`--showConfig outputs config info and exits 1`] = `
       "transformIgnorePatterns": [
         "/node_modules/"
       ],
+      "verbose": null,
       "watchPathIgnorePatterns": []
     }
   ],

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

@@ -72,6 +72,14 @@ module.exports = {
   // Force coverage collection from ignored files using an array of glob patterns
   // forceCoverageMatch: [],
 
+  // Prevents overriding node's core module methods so to prevent memory leaks
+  // freezeCoreModules: false,
+
+  // Array of node core modules which will not be frozen
+  // freezeCoreModulesWhitelist: [
+  //   \\"crypto\\"
+  // ],
+
   // A path to a module which exports an async function that is triggered once before all test suites
   // globalSetup: null,
 

packages/jest-config/src/Defaults.ts

@@ -31,6 +31,8 @@ const defaultOptions: Config.DefaultOptions = {
   expand: false,
   filter: null,
   forceCoverageMatch: [],
+  freezeCoreModules: false,
+  freezeCoreModulesWhitelist: ['crypto'],
   globalSetup: null,
   globalTeardown: null,
   globals: {},

packages/jest-config/src/Descriptions.ts

@@ -31,6 +31,10 @@ const descriptions: {[key in keyof Config.InitialOptions]: string} = {
     'Make calling deprecated APIs throw helpful error messages',
   forceCoverageMatch:
     'Force coverage collection from ignored files using an array of glob patterns',
+  freezeCoreModules:
+    "Prevents overriding node's core module methods so to prevent memory leaks",
+  freezeCoreModulesWhitelist:
+    'Array of node core modules which will not be frozen',
   globalSetup:
     'A path to a module which exports an async function that is triggered once before all test suites',
   globalTeardown:

packages/jest-config/src/ValidConfig.ts

@@ -48,6 +48,8 @@ const initialOptions: Config.InitialOptions = {
   filter: '<rootDir>/filter.js',
   forceCoverageMatch: ['**/*.t.js'],
   forceExit: false,
+  freezeCoreModules: false,
+  freezeCoreModulesWhitelist: ['crypto'],
   globalSetup: 'setup.js',
   globalTeardown: 'teardown.js',
   globals: {__DEV__: true},

packages/jest-config/src/index.ts

@@ -174,6 +174,8 @@ const groupOptions = (
     extraGlobals: options.extraGlobals,
     filter: options.filter,
     forceCoverageMatch: options.forceCoverageMatch,
+    freezeCoreModules: options.freezeCoreModules,
+    freezeCoreModulesWhitelist: options.freezeCoreModulesWhitelist,
     globalSetup: options.globalSetup,
     globalTeardown: options.globalTeardown,
     globals: options.globals,
@@ -211,6 +213,7 @@ const groupOptions = (
     transform: options.transform,
     transformIgnorePatterns: options.transformIgnorePatterns,
     unmockedModulePathPatterns: options.unmockedModulePathPatterns,
+    verbose: options.verbose,
     watchPathIgnorePatterns: options.watchPathIgnorePatterns,
   }),
 });

packages/jest-config/src/normalize.ts

@@ -852,6 +852,8 @@ export default function normalize(
       case 'findRelatedTests':
       case 'forceCoverageMatch':
       case 'forceExit':
+      case 'freezeCoreModules':
+      case 'freezeCoreModulesWhitelist':
       case 'lastCommit':
       case 'listTests':
       case 'logHeapUsage':

packages/jest-core/src/lib/__tests__/__snapshots__/log_debug_messages.test.ts.snap

@@ -16,6 +16,10 @@ exports[`prints the config object 1`] = `
     "extraGlobals": [],
     "filter": null,
     "forceCoverageMatch": [],
+    "freezeCoreModules": false,
+    "freezeCoreModulesWhitelist": [
+      "crypto"
+    ],
     "globalSetup": null,
     "globalTeardown": null,
     "globals": {},
@@ -61,6 +65,7 @@ exports[`prints the config object 1`] = `
     "transform": [],
     "transformIgnorePatterns": [],
     "unmockedModulePathPatterns": null,
+    "verbose": false,
     "watchPathIgnorePatterns": []
   },
   "globalConfig": {

packages/jest-runtime/src/__tests__/runtime_require_module.test.js

@@ -184,6 +184,54 @@ describe('Runtime requireModule', () => {
       }).not.toThrow();
     }));
 
+  it('prevents overriding core module methods when `config.freezeCoreModules` is set', () =>
+    createRuntime(__filename, {freezeCoreModules: true}).then(runtime => {
+      const fs = runtime.requireModule(runtime.__mockRootPath, 'fs');
+      const originalFsClose = fs.close;
+
+      fs.close = () => {};
+
+      expect(fs.close).toBe(originalFsClose);
+    }));
+
+  it('allows mocking core module methods when `config.freezeCoreModules` is set', () =>
+    createRuntime(__filename, {freezeCoreModules: true}).then(runtime => {
+      const root = runtime.requireModule(runtime.__mockRootPath);
+      const fs = runtime.requireModule(runtime.__mockRootPath, 'fs');
+      let mockImplementationCalled = false;
+      const spy = root.jest.spyOn(fs, 'close').mockImplementation(() => {
+        mockImplementationCalled = true;
+      });
+
+      fs.close();
+
+      expect(mockImplementationCalled).toBe(true);
+      expect(spy).toHaveBeenCalled();
+    }));
+
+  it('allows overriding `crypto` core module methods by default', () =>
+    createRuntime(__filename, {freezeCoreModules: true}).then(runtime => {
+      const crypto = runtime.requireModule(runtime.__mockRootPath, 'crypto');
+      const cryptoRandomBytesOverride = () => {};
+
+      crypto.randomBytes = cryptoRandomBytesOverride;
+
+      expect(crypto.randomBytes).toBe(cryptoRandomBytesOverride);
+    }));
+
+  it('allows overriding core module methods when module is in `config.freezeCoreModulesWhitelist`', () =>
+    createRuntime(__filename, {
+      freezeCoreModules: true,
+      freezeCoreModulesWhitelist: ['fs'],
+    }).then(runtime => {
+      const fs = runtime.requireModule(runtime.__mockRootPath, 'fs');
+      const fsCloseOverride = () => {};
+
+      fs.close = fsCloseOverride;
+
+      expect(fs.close).toBe(fsCloseOverride);
+    }));
+
   it('finds and loads JSON files without file extension', () =>
     createRuntime(__filename).then(runtime => {
       const exports = runtime.requireModule(

packages/jest-runtime/src/index.ts

@@ -18,7 +18,7 @@ import jestMock = require('jest-mock');
 import HasteMap = require('jest-haste-map');
 import {formatStackTrace, separateMessageFromStack} from 'jest-message-util';
 import Resolver = require('jest-resolve');
-import {createDirectory, deepCyclicCopy} from 'jest-util';
+import {ErrorWithStack, createDirectory, deepCyclicCopy} from 'jest-util';
 import {escapePathForRegex} from 'jest-regex-util';
 import Snapshot = require('jest-snapshot');
 import {
@@ -84,6 +84,7 @@ class Runtime {
 
   private _cacheFS: CacheFS;
   private _config: Config.ProjectConfig;
+  private _coreModulesProxyCache: {[moduleName: string]: any};
   private _coverageOptions: ShouldInstrumentOptions;
   private _currentlyExecutingModulePath: string;
   private _environment: JestEnvironment;
@@ -125,6 +126,7 @@ class Runtime {
       collectCoverageFrom: [],
       collectCoverageOnlyFrom: null,
     };
+    this._coreModulesProxyCache = Object.create(null);
     this._currentlyExecutingModulePath = '';
     this._environment = environment;
     this._explicitShouldMock = Object.create(null);
@@ -776,7 +778,46 @@ class Runtime {
       return this._environment.global.process;
     }
 
-    return require(moduleName);
+    const module = require(moduleName);
+
+    if (
+      !this._config.freezeCoreModules ||
+      this._config.freezeCoreModulesWhitelist.includes(moduleName)
+    ) {
+      return module;
+    }
+
+    if (this._coreModulesProxyCache[moduleName]) {
+      return this._coreModulesProxyCache[moduleName];
+    }
+
+    const set = (
+      target: object,
+      property: PropertyKey,
+      value: any,
+      receiver: any,
+    ) => {
+      if (typeof value !== 'function' || value._isMockFunction) {
+        return Reflect.set(target, property, value, receiver);
+      }
+
+      if (this._config.verbose) {
+        console.warn(
+          new ErrorWithStack(
+            `Trying to override method '${property.toString()}' of a frozen core module '${moduleName}'`,
+            set,
+          ),
+        );
+      }
+
+      return true;
+    };
+
+    const proxy = new Proxy(module, {set});
+
+    this._coreModulesProxyCache[moduleName] = proxy;
+
+    return proxy;
   }
 
   private _generateMock(from: Config.Path, moduleName: string) {

packages/jest-transform/src/__tests__/__snapshots__/script_transformer.test.js.snap

@@ -17,6 +17,10 @@ Object {
     "extraGlobals": Array [],
     "filter": null,
     "forceCoverageMatch": Array [],
+    "freezeCoreModules": false,
+    "freezeCoreModulesWhitelist": Array [
+      "crypto",
+    ],
     "globalSetup": null,
     "globalTeardown": null,
     "globals": Object {},
@@ -67,6 +71,7 @@ Object {
       "/node_modules/",
     ],
     "unmockedModulePathPatterns": null,
+    "verbose": false,
     "watchPathIgnorePatterns": Array [],
   },
   "instrument": true,
@@ -218,7 +223,7 @@ exports[`ScriptTransformer uses multiple preprocessors 1`] = `
           const TRANSFORMED = {
             filename: '/fruits/banana.js',
             script: 'module.exports = \\"banana\\";',
-            config: '{\\"automock\\":false,\\"browser\\":false,\\"cache\\":true,\\"cacheDirectory\\":\\"/cache/\\",\\"clearMocks\\":false,\\"coveragePathIgnorePatterns\\":[],\\"cwd\\":\\"/test_root_dir/\\",\\"detectLeaks\\":false,\\"detectOpenHandles\\":false,\\"errorOnDeprecated\\":false,\\"extraGlobals\\":[],\\"filter\\":null,\\"forceCoverageMatch\\":[],\\"globalSetup\\":null,\\"globalTeardown\\":null,\\"globals\\":{},\\"haste\\":{\\"providesModuleNodeModules\\":[]},\\"moduleDirectories\\":[],\\"moduleFileExtensions\\":[\\"js\\"],\\"moduleLoader\\":\\"/test_module_loader_path\\",\\"moduleNameMapper\\":[],\\"modulePathIgnorePatterns\\":[],\\"modulePaths\\":[],\\"name\\":\\"test\\",\\"prettierPath\\":\\"prettier\\",\\"resetMocks\\":false,\\"resetModules\\":false,\\"resolver\\":null,\\"restoreMocks\\":false,\\"rootDir\\":\\"/\\",\\"roots\\":[],\\"runner\\":\\"jest-runner\\",\\"setupFiles\\":[],\\"setupFilesAfterEnv\\":[],\\"skipFilter\\":false,\\"skipNodeResolution\\":false,\\"snapshotResolver\\":null,\\"snapshotSerializers\\":[],\\"testEnvironment\\":\\"node\\",\\"testEnvironmentOptions\\":{},\\"testLocationInResults\\":false,\\"testMatch\\":[],\\"testPathIgnorePatterns\\":[],\\"testRegex\\":[\\"\\\\\\\\.test\\\\\\\\.js$\\"],\\"testRunner\\":\\"jest-jasmine2\\",\\"testURL\\":\\"http://localhost\\",\\"timers\\":\\"real\\",\\"transform\\":[[\\"^.+\\\\\\\\.js$\\",\\"test_preprocessor\\"],[\\"^.+\\\\\\\\.css$\\",\\"css-preprocessor\\"]],\\"transformIgnorePatterns\\":[\\"/node_modules/\\"],\\"unmockedModulePathPatterns\\":null,\\"watchPathIgnorePatterns\\":[]}',
+            config: '{\\"automock\\":false,\\"browser\\":false,\\"cache\\":true,\\"cacheDirectory\\":\\"/cache/\\",\\"clearMocks\\":false,\\"coveragePathIgnorePatterns\\":[],\\"cwd\\":\\"/test_root_dir/\\",\\"detectLeaks\\":false,\\"detectOpenHandles\\":false,\\"errorOnDeprecated\\":false,\\"extraGlobals\\":[],\\"filter\\":null,\\"forceCoverageMatch\\":[],\\"freezeCoreModules\\":false,\\"freezeCoreModulesWhitelist\\":[\\"crypto\\"],\\"globalSetup\\":null,\\"globalTeardown\\":null,\\"globals\\":{},\\"haste\\":{\\"providesModuleNodeModules\\":[]},\\"moduleDirectories\\":[],\\"moduleFileExtensions\\":[\\"js\\"],\\"moduleLoader\\":\\"/test_module_loader_path\\",\\"moduleNameMapper\\":[],\\"modulePathIgnorePatterns\\":[],\\"modulePaths\\":[],\\"name\\":\\"test\\",\\"prettierPath\\":\\"prettier\\",\\"resetMocks\\":false,\\"resetModules\\":false,\\"resolver\\":null,\\"restoreMocks\\":false,\\"rootDir\\":\\"/\\",\\"roots\\":[],\\"runner\\":\\"jest-runner\\",\\"setupFiles\\":[],\\"setupFilesAfterEnv\\":[],\\"skipFilter\\":false,\\"skipNodeResolution\\":false,\\"snapshotResolver\\":null,\\"snapshotSerializers\\":[],\\"testEnvironment\\":\\"node\\",\\"testEnvironmentOptions\\":{},\\"testLocationInResults\\":false,\\"testMatch\\":[],\\"testPathIgnorePatterns\\":[],\\"testRegex\\":[\\"\\\\\\\\.test\\\\\\\\.js$\\"],\\"testRunner\\":\\"jest-jasmine2\\",\\"testURL\\":\\"http://localhost\\",\\"timers\\":\\"real\\",\\"transform\\":[[\\"^.+\\\\\\\\.js$\\",\\"test_preprocessor\\"],[\\"^.+\\\\\\\\.css$\\",\\"css-preprocessor\\"]],\\"transformIgnorePatterns\\":[\\"/node_modules/\\"],\\"unmockedModulePathPatterns\\":null,\\"verbose\\":false,\\"watchPathIgnorePatterns\\":[]}',
           };
         
 }});"
@@ -244,7 +249,7 @@ exports[`ScriptTransformer uses the supplied preprocessor 1`] = `
           const TRANSFORMED = {
             filename: '/fruits/banana.js',
             script: 'module.exports = \\"banana\\";',
-            config: '{\\"automock\\":false,\\"browser\\":false,\\"cache\\":true,\\"cacheDirectory\\":\\"/cache/\\",\\"clearMocks\\":false,\\"coveragePathIgnorePatterns\\":[],\\"cwd\\":\\"/test_root_dir/\\",\\"detectLeaks\\":false,\\"detectOpenHandles\\":false,\\"errorOnDeprecated\\":false,\\"extraGlobals\\":[],\\"filter\\":null,\\"forceCoverageMatch\\":[],\\"globalSetup\\":null,\\"globalTeardown\\":null,\\"globals\\":{},\\"haste\\":{\\"providesModuleNodeModules\\":[]},\\"moduleDirectories\\":[],\\"moduleFileExtensions\\":[\\"js\\"],\\"moduleLoader\\":\\"/test_module_loader_path\\",\\"moduleNameMapper\\":[],\\"modulePathIgnorePatterns\\":[],\\"modulePaths\\":[],\\"name\\":\\"test\\",\\"prettierPath\\":\\"prettier\\",\\"resetMocks\\":false,\\"resetModules\\":false,\\"resolver\\":null,\\"restoreMocks\\":false,\\"rootDir\\":\\"/\\",\\"roots\\":[],\\"runner\\":\\"jest-runner\\",\\"setupFiles\\":[],\\"setupFilesAfterEnv\\":[],\\"skipFilter\\":false,\\"skipNodeResolution\\":false,\\"snapshotResolver\\":null,\\"snapshotSerializers\\":[],\\"testEnvironment\\":\\"node\\",\\"testEnvironmentOptions\\":{},\\"testLocationInResults\\":false,\\"testMatch\\":[],\\"testPathIgnorePatterns\\":[],\\"testRegex\\":[\\"\\\\\\\\.test\\\\\\\\.js$\\"],\\"testRunner\\":\\"jest-jasmine2\\",\\"testURL\\":\\"http://localhost\\",\\"timers\\":\\"real\\",\\"transform\\":[[\\"^.+\\\\\\\\.js$\\",\\"test_preprocessor\\"]],\\"transformIgnorePatterns\\":[\\"/node_modules/\\"],\\"unmockedModulePathPatterns\\":null,\\"watchPathIgnorePatterns\\":[]}',
+            config: '{\\"automock\\":false,\\"browser\\":false,\\"cache\\":true,\\"cacheDirectory\\":\\"/cache/\\",\\"clearMocks\\":false,\\"coveragePathIgnorePatterns\\":[],\\"cwd\\":\\"/test_root_dir/\\",\\"detectLeaks\\":false,\\"detectOpenHandles\\":false,\\"errorOnDeprecated\\":false,\\"extraGlobals\\":[],\\"filter\\":null,\\"forceCoverageMatch\\":[],\\"freezeCoreModules\\":false,\\"freezeCoreModulesWhitelist\\":[\\"crypto\\"],\\"globalSetup\\":null,\\"globalTeardown\\":null,\\"globals\\":{},\\"haste\\":{\\"providesModuleNodeModules\\":[]},\\"moduleDirectories\\":[],\\"moduleFileExtensions\\":[\\"js\\"],\\"moduleLoader\\":\\"/test_module_loader_path\\",\\"moduleNameMapper\\":[],\\"modulePathIgnorePatterns\\":[],\\"modulePaths\\":[],\\"name\\":\\"test\\",\\"prettierPath\\":\\"prettier\\",\\"resetMocks\\":false,\\"resetModules\\":false,\\"resolver\\":null,\\"restoreMocks\\":false,\\"rootDir\\":\\"/\\",\\"roots\\":[],\\"runner\\":\\"jest-runner\\",\\"setupFiles\\":[],\\"setupFilesAfterEnv\\":[],\\"skipFilter\\":false,\\"skipNodeResolution\\":false,\\"snapshotResolver\\":null,\\"snapshotSerializers\\":[],\\"testEnvironment\\":\\"node\\",\\"testEnvironmentOptions\\":{},\\"testLocationInResults\\":false,\\"testMatch\\":[],\\"testPathIgnorePatterns\\":[],\\"testRegex\\":[\\"\\\\\\\\.test\\\\\\\\.js$\\"],\\"testRunner\\":\\"jest-jasmine2\\",\\"testURL\\":\\"http://localhost\\",\\"timers\\":\\"real\\",\\"transform\\":[[\\"^.+\\\\\\\\.js$\\",\\"test_preprocessor\\"]],\\"transformIgnorePatterns\\":[\\"/node_modules/\\"],\\"unmockedModulePathPatterns\\":null,\\"verbose\\":false,\\"watchPathIgnorePatterns\\":[]}',
           };
         
 }});"

packages/jest-types/src/Config.ts

@@ -52,6 +52,8 @@ export type DefaultOptions = {
   expand: boolean;
   filter: Path | null | undefined;
   forceCoverageMatch: Array<Glob>;
+  freezeCoreModules: boolean;
+  freezeCoreModulesWhitelist: Array<string>;
   globals: ConfigGlobals;
   globalSetup: string | null | undefined;
   globalTeardown: string | null | undefined;
@@ -150,6 +152,8 @@ export type InitialOptions = Partial<{
   findRelatedTests: boolean;
   forceCoverageMatch: Array<Glob>;
   forceExit: boolean;
+  freezeCoreModules?: boolean;
+  freezeCoreModulesWhitelist?: Array<string>;
   json: boolean;
   globals: ConfigGlobals;
   globalSetup: string | null | undefined;
@@ -386,6 +390,8 @@ export type ProjectConfig = {
   extraGlobals: Array<keyof NodeJS.Global>;
   filter: Path | null | undefined;
   forceCoverageMatch: Array<Glob>;
+  freezeCoreModules: boolean;
+  freezeCoreModulesWhitelist: Array<string>;
   globalSetup: string | null | undefined;
   globalTeardown: string | null | undefined;
   globals: ConfigGlobals;
@@ -424,6 +430,7 @@ export type ProjectConfig = {
   transformIgnorePatterns: Array<Glob>;
   watchPathIgnorePatterns: Array<string>;
   unmockedModulePathPatterns: Array<string> | null | undefined;
+  verbose: boolean | null | undefined;
 };
 
 export type Argv = Arguments<