Add support for NODE_PRESERVE_SYMLINKS and --preserve-symlinks behavior

.gitignore

@@ -6,6 +6,7 @@
 /examples/*/node_modules/
 /examples/mongodb/globalConfig.json
 
+/e2e/preserve-symlinks/*
 /e2e/*/node_modules
 /e2e/*/.pnp
 /e2e/*/.pnp.js

CHANGELOG.md

@@ -32,6 +32,7 @@
 - `[jest-config]` Support config files exporting (`async`) `function`s ([#10001](https://github.com/facebook/jest/pull/10001))
 - `[jest-cli, jest-core]` Add `--selectProjects` CLI argument to filter test suites by project name ([#8612](https://github.com/facebook/jest/pull/8612))
 - `[jest-cli, jest-init]` Add `coverageProvider` to `jest --init` prompts ([#10044](https://github.com/facebook/jest/pull/10044))
+- `[*]` Add support for NODE_PRESERVE_SYMLINKS and --preserve-symlinks behavior
 
 ### Fixes
 

e2e/__tests__/preserveSymlinks.ts

@@ -0,0 +1,95 @@
+/**
+ * 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 {join, resolve} from 'path';
+import {
+  existsSync,
+  mkdirSync,
+  rmdirSync,
+  symlinkSync,
+  unlinkSync,
+} from 'graceful-fs';
+
+import runJest from '../runJest';
+import {extractSummary} from '../Utils';
+
+const destRoot = resolve(__dirname, '../preserve-symlinks');
+const srcRoot = resolve(__dirname, '../symlinked-source-dir');
+
+const files = [
+  'package.json',
+  'a.js',
+  'b.js',
+  'ab.js',
+  '__tests__/a.test.js',
+  '__tests__/b.test.js',
+  '__tests__/ab.test.js',
+];
+
+function cleanup() {
+  files
+    .map(f => join(destRoot, f))
+    .filter(f => existsSync(f))
+    .forEach(f => {
+      unlinkSync(f);
+    });
+  if (existsSync(join(destRoot, '__tests__'))) {
+    rmdirSync(join(destRoot, '__tests__'));
+  }
+  if (existsSync(destRoot)) {
+    rmdirSync(destRoot);
+  }
+}
+
+beforeAll(() => {
+  cleanup();
+  mkdirSync(destRoot);
+  mkdirSync(join(destRoot, '__tests__'));
+  files.forEach(f => {
+    symlinkSync(join(srcRoot, f), join(destRoot, f));
+  });
+});
+
+afterAll(() => {
+  cleanup();
+});
+
+test('preserving symlinks with environment variable', () => {
+  const {stderr, exitCode} = runJest('preserve-symlinks', ['--no-watchman'], {
+    preserveSymlinks: '1',
+  });
+  const {summary, rest} = extractSummary(stderr);
+  expect(exitCode).toEqual(0);
+  expect(rest.split('\n').length).toEqual(3);
+  expect(rest).toMatch('PASS __tests__/ab.test.js');
+  expect(rest).toMatch('PASS __tests__/a.test.js');
+  expect(rest).toMatch('PASS __tests__/b.test.js');
+  expect(summary).toMatch('Test Suites: 3 passed, 3 total');
+  expect(summary).toMatch('Tests:       3 passed, 3 total');
+  expect(summary).toMatch('Snapshots:   0 total');
+});
+
+test('preserving symlinks with --preserve-symlinks node flag', () => {
+  const {stderr, exitCode} = runJest('preserve-symlinks', ['--no-watchman'], {
+    nodeFlags: ['--preserve-symlinks'],
+  });
+  const {summary, rest} = extractSummary(stderr);
+  expect(exitCode).toEqual(0);
+  expect(rest.split('\n').length).toEqual(3);
+  expect(rest).toMatch('PASS __tests__/ab.test.js');
+  expect(rest).toMatch('PASS __tests__/a.test.js');
+  expect(rest).toMatch('PASS __tests__/b.test.js');
+  expect(summary).toMatch('Test Suites: 3 passed, 3 total');
+  expect(summary).toMatch('Tests:       3 passed, 3 total');
+  expect(summary).toMatch('Snapshots:   0 total');
+});
+
+test('no preserve symlinks configuration', () => {
+  const {exitCode, stdout} = runJest('preserve-symlinks', ['--no-watchman']);
+  expect(exitCode).toEqual(1);
+  expect(stdout).toMatch('No tests found, exiting with code 1');
+});

e2e/runJest.ts

@@ -18,6 +18,8 @@ import {normalizeIcons} from './Utils';
 const JEST_PATH = path.resolve(__dirname, '../packages/jest-cli/bin/jest.js');
 
 type RunJestOptions = {
+  preserveSymlinks?: string;
+  nodeFlags?: Array<string>;
   nodeOptions?: string;
   nodePath?: string;
   skipPkgJsonCheck?: boolean; // don't complain if can't find package.json
@@ -78,8 +80,13 @@ function spawnJest(
 
   if (options.nodeOptions) env['NODE_OPTIONS'] = options.nodeOptions;
   if (options.nodePath) env['NODE_PATH'] = options.nodePath;
+  if (options.preserveSymlinks)
+    env['NODE_PRESERVE_SYMLINKS'] = options.preserveSymlinks;
 
   const spawnArgs = [JEST_PATH, ...args];
+  if (options.nodeFlags) {
+    spawnArgs.unshift(...options.nodeFlags);
+  }
   const spawnOptions = {
     cwd: dir,
     env,

e2e/symlinked-source-dir/__tests__/a.test.js

@@ -0,0 +1,12 @@
+/**
+ * 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.
+ *
+ */
+const a = require('../a');
+
+test('a', () => {
+  expect(a()).toEqual('a');
+});

e2e/symlinked-source-dir/__tests__/ab.test.js

@@ -0,0 +1,12 @@
+/**
+ * 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.
+ *
+ */
+const ab = require('../ab');
+
+test('ab', () => {
+  expect(ab()).toEqual('ab');
+});

e2e/symlinked-source-dir/__tests__/b.test.js

@@ -0,0 +1,12 @@
+/**
+ * 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.
+ *
+ */
+const b = require('../b');
+
+test('b', () => {
+  expect(b()).toEqual('b');
+});

e2e/symlinked-source-dir/a.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.
+ *
+ */
+module.exports = function a() {
+  return 'a';
+};

e2e/symlinked-source-dir/ab.js

@@ -0,0 +1,13 @@
+/**
+ * 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.
+ *
+ */
+const a = require('./a');
+const b = require('./b');
+
+module.exports = function ab() {
+  return a() + b();
+};

e2e/symlinked-source-dir/b.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.
+ *
+ */
+module.exports = function b() {
+  return 'b';
+};

e2e/symlinked-source-dir/package.json

@@ -0,0 +1,5 @@
+{
+  "jest": {
+    "testEnvironment": "node"
+  }
+}

packages/jest-config/src/Defaults.ts

@@ -7,6 +7,7 @@
 
 import type {Config} from '@jest/types';
 import {replacePathSepForRegex} from 'jest-regex-util';
+import {shouldPreserveSymlinks} from 'jest-util';
 import {NODE_MODULES} from './constants';
 import getCacheDirectory from './getCacheDirectory';
 
@@ -66,7 +67,7 @@ const defaultOptions: Config.DefaultOptions = {
   useStderr: false,
   watch: false,
   watchPathIgnorePatterns: [],
-  watchman: true,
+  watchman: !shouldPreserveSymlinks(),
 };
 
 export default defaultOptions;

packages/jest-haste-map/src/crawlers/node.ts

@@ -8,6 +8,7 @@
 import * as path from 'path';
 import {spawn} from 'child_process';
 import * as fs from 'graceful-fs';
+import {shouldPreserveSymlinks} from 'jest-util';
 import H from '../constants';
 import * as fastPath from '../lib/fast_path';
 import type {
@@ -17,6 +18,8 @@ import type {
   InternalHasteMap,
 } from '../types';
 
+const preserveSymlinks = shouldPreserveSymlinks();
+
 type Result = Array<[/* id */ string, /* mtime */ number, /* size */ number]>;
 
 type Callback = (result: Result) => void;
@@ -75,7 +78,7 @@ function find(
         }
 
         if (typeof entry !== 'string') {
-          if (entry.isSymbolicLink()) {
+          if (!preserveSymlinks && entry.isSymbolicLink()) {
             return;
           }
 
@@ -92,7 +95,7 @@ function find(
 
           // This logic is unnecessary for node > v10.10, but leaving it in
           // since we need it for backwards-compatibility still.
-          if (!err && stat && !stat.isSymbolicLink()) {
+          if (!err && stat && (preserveSymlinks || !stat.isSymbolicLink())) {
             if (stat.isDirectory()) {
               search(file);
             } else {
@@ -129,7 +132,13 @@ function findNative(
   callback: Callback,
 ): void {
   const args = Array.from(roots);
-  args.push('-type', 'f');
+  if (preserveSymlinks) {
+    // follow symlinks to determine file type
+    args.unshift('-L');
+    args.push('( -not -type d )');
+  } else {
+    args.push('-type', 'f');
+  }
   if (extensions.length) {
     args.push('(');
   }

packages/jest-util/src/index.ts

@@ -23,5 +23,6 @@ import * as preRunMessage from './preRunMessage';
 export {default as pluralize} from './pluralize';
 export {default as formatTime} from './formatTime';
 export {default as tryRealpath} from './tryRealpath';
+export {default as shouldPreserveSymlinks} from './shouldPreserveSymlinks';
 
 export {preRunMessage, specialChars};

packages/jest-util/src/shouldPreserveSymlinks.ts

@@ -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.
+ */
+
+export default (): boolean =>
+  Boolean(process.env.NODE_PRESERVE_SYMLINKS) ||
+  process.execArgv.includes('--preserve-symlinks');

packages/jest-util/src/tryRealpath.ts

@@ -7,8 +7,14 @@
 
 import {realpathSync} from 'graceful-fs';
 import type {Config} from '@jest/types';
+import shouldPreserveSymlinks from './shouldPreserveSymlinks';
+
+const preserveSymlinks = shouldPreserveSymlinks();
 
 export default function tryRealpath(path: Config.Path): Config.Path {
+  if (preserveSymlinks) {
+    return path;
+  }
   try {
     path = realpathSync.native(path);
   } catch (error) {