From a919713a2a0fa13958319bbe07cc17d1396d1062 Mon Sep 17 00:00:00 2001
From: Simen Bekkhus <sbekkhus91@gmail.com>
Date: Sat, 6 Jan 2018 12:17:26 +0100
Subject: [PATCH] fix(jest-runtime): make sure a module can never be its own
 parent

Fixes #5235
---
 .../__tests__/module_parent_null_in_test.js     | 17 +++++++++++++++++
 .../__tests__/index.js                          | 13 +++++++++++++
 .../module_parent_null_in_test/package.json     |  4 ++++
 .../runtime_internal_module_registry.test.js    |  2 +-
 packages/jest-runtime/src/index.js              |  4 ++++
 5 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100644 integration_tests/__tests__/module_parent_null_in_test.js
 create mode 100644 integration_tests/module_parent_null_in_test/__tests__/index.js
 create mode 100644 integration_tests/module_parent_null_in_test/package.json

diff --git a/integration_tests/__tests__/module_parent_null_in_test.js b/integration_tests/__tests__/module_parent_null_in_test.js
new file mode 100644
index 000000000000..0b188ff36950
--- /dev/null
+++ b/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);
+});
diff --git a/integration_tests/module_parent_null_in_test/__tests__/index.js b/integration_tests/module_parent_null_in_test/__tests__/index.js
new file mode 100644
index 000000000000..27bbab9627b4
--- /dev/null
+++ b/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();
+});
diff --git a/integration_tests/module_parent_null_in_test/package.json b/integration_tests/module_parent_null_in_test/package.json
new file mode 100644
index 000000000000..0b6365577734
--- /dev/null
+++ b/integration_tests/module_parent_null_in_test/package.json
@@ -0,0 +1,4 @@
+{
+  "jest": {
+  }
+}
diff --git a/integration_tests/runtime-internal-module-registry/__tests__/runtime_internal_module_registry.test.js b/integration_tests/runtime-internal-module-registry/__tests__/runtime_internal_module_registry.test.js
index 4d7fb144e05c..d9af77223a99 100644
--- a/integration_tests/runtime-internal-module-registry/__tests__/runtime_internal_module_registry.test.js
+++ b/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');
diff --git a/packages/jest-runtime/src/index.js b/packages/jest-runtime/src/index.js
index 9a322f6fc32d..1f9e17bab900 100644
--- a/packages/jest-runtime/src/index.js
+++ b/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),