fix(jest-runtime): make sure a module can never be its own parent

CHANGELOG.md

@@ -2,7 +2,8 @@
 
 ### Fixes
 
-* `[jest-cli]` Treat dumb terminals as noninteractive ([#5237](https://github.com/facebook/jest/pull/5237))
+* `[jest-cli]` Treat dumb terminals as noninteractive
+  ([#5237](https://github.com/facebook/jest/pull/5237))
 * `[jest-cli]` `jest --onlyChanged --changedFilesWithAncestor` now also works
   with git. ([#5189](https://github.com/facebook/jest/pull/5189))
 * `[jest-config]` fix unexpected condition to avoid infinite recursion in
@@ -11,6 +12,8 @@
   ([#5230](https://github.com/facebook/jest/pull/5230))
 * `[expect]` Do not override `Error` stack (with `Error.captureStackTrace`) for
   custom matchers. ([#5162](https://github.com/facebook/jest/pull/5162))
+* `[jest-runtime]` Make sure a module cannot be its own parent.
+  ([#5241](https://github.com/facebook/jest/pull/5241))
 
 ### Features
 
@@ -29,14 +32,15 @@
 * `[jest-runner]` test environments are now passed a new `options` parameter.
   Currently this only has the `console` which is the test console that Jest will
   expose to tests. ([#5223](https://github.com/facebook/jest/issues/5223))
-* `[jest-environment-jsdom]` pass the `options.console` to a custom
-  instance of `virtualConsole` so jsdom is using the same console as the
-  test. ([#5223](https://github.com/facebook/jest/issues/5223))
+* `[jest-environment-jsdom]` pass the `options.console` to a custom instance of
+  `virtualConsole` so jsdom is using the same console as the test.
+  ([#5223](https://github.com/facebook/jest/issues/5223))
 
 ### Chore & Maintenance
 
 * `[docs]` Describe the order of execution of describe and test blocks.
-  ([#5217](https://github.com/facebook/jest/pull/5217), [#5238](https://github.com/facebook/jest/pull/5238))
+  ([#5217](https://github.com/facebook/jest/pull/5217),
+  [#5238](https://github.com/facebook/jest/pull/5238))
 
 ## jest 22.0.4
 

integration_tests/__tests__/module_parent_null_in_test.js

@@ -0,0 +1,17 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc. 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.
+ *
+ * @flow
+ */
+'use strict';
+
+const runJest = require('../runJest');
+
+test('module.parent should be null in test files', () => {
+  const {status} = runJest('module_parent_null_in_test');
+
+  expect(status).toBe(0);
+});

integration_tests/module_parent_null_in_test/__tests__/index.js

@@ -0,0 +1,13 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc. 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.
+ */
+
+'use strict';
+
+test('moduleNameMapping wrong configuration', () => {
+  expect(module).not.toBe(module.parent);
+  expect(module.parent).toBeNull();
+});

integration_tests/module_parent_null_in_test/package.json

@@ -0,0 +1,4 @@
+{
+  "jest": {
+  }
+}

integration_tests/runtime-internal-module-registry/__tests__/runtime_internal_module_registry.test.js

@@ -13,7 +13,7 @@ describe('Runtime internal module registry', () => {
   it('behaves correctly when requiring a module that is used by jest internals', () => {
     const fs = require('fs');
 
-    // We require from this crazy path so that we can mimick Jest (and it's
+    // We require from this crazy path so that we can mimick Jest (and its
     // transitive deps) being installed along side a projects deps (e.g. with an
     // NPM3 flat dep tree)
     const jestUtil = require('../../../packages/jest-util');

packages/jest-runtime/src/index.js

@@ -509,6 +509,10 @@ class Runtime {
       ({
         enumerable: true,
         get() {
+          if (localModule.filename === from) {
+            return null;
+          }
+
           return moduleRegistry[from] || null;
         },
       }: Object),