feat(jest-haste-map): Enable crawling for symlink test files

CHANGELOG.md

@@ -26,6 +26,7 @@
 - `[jest-environment-node]` Implement `compileFunction` ([#9140](https://github.com/facebook/jest/pull/9140))
 - `[@jest/fake-timers]` Add Lolex as implementation of fake timers ([#8897](https://github.com/facebook/jest/pull/8897))
 - `[jest-get-type]` Add `BigInt` support. ([#8382](https://github.com/facebook/jest/pull/8382))
+- `[jest-haste-map]` Enable crawling for symlinked test files ([#9350](https://github.com/facebook/jest/issues/9350))
 - `[jest-matcher-utils]` Add `BigInt` support to `ensureNumbers` `ensureActualIsNumber`, `ensureExpectedIsNumber` ([#8382](https://github.com/facebook/jest/pull/8382))
 - `[jest-reporters]` Export utils for path formatting ([#9162](https://github.com/facebook/jest/pull/9162))
 - `[jest-runner]` Warn if a worker had to be force exited ([#8206](https://github.com/facebook/jest/pull/8206))

e2e/Utils.ts

@@ -90,6 +90,25 @@ export const writeFiles = (
   });
 };
 
+export const writeSymlinks = (
+  directory: string,
+  symlinks: {[existingFile: string]: string},
+) => {
+  createDirectory(directory);
+  Object.keys(symlinks).forEach(fileOrPath => {
+    const symLinkPath = symlinks[fileOrPath];
+    const dirname = path.dirname(symLinkPath);
+
+    if (dirname !== '/') {
+      createDirectory(path.join(directory, dirname));
+    }
+    fs.symlinkSync(
+      path.resolve(directory, ...fileOrPath.split('/')),
+      path.resolve(directory, ...symLinkPath.split('/')),
+    );
+  });
+};
+
 const NUMBER_OF_TESTS_TO_FORCE_USING_WORKERS = 25;
 /**
  * Forces Jest to use workers by generating many test files to run.

e2e/__tests__/crawlSymlinks.test.ts

@@ -0,0 +1,34 @@
+import runJest from '../runJest';
+import {tmpdir} from 'os';
+import * as path from 'path';
+import {writeFiles, writeSymlinks} from '../Utils';
+import * as fs from 'fs';
+const DIR = path.resolve(tmpdir(), 'crawl-symlinks-test');
+
+test('Node crawler picks up symlinked files', () => {
+  fs.rmdirSync(DIR, {recursive: true});
+
+  writeFiles(DIR, {
+    'package.json': `
+            {
+              "jest": {
+                "testMatch": ["<rootDir>/test-files/test.js"]
+              }
+            }
+          `,
+    'symlinked-files/test.js': `
+            test('1+1', () => {
+              expect(1).toBe(1);
+            });
+          `,
+  });
+
+  writeSymlinks(DIR, {
+    'symlinked-files/test.js': 'test-files/test.js',
+  });
+
+  const {stdout, stderr, exitCode} = runJest(DIR, ['--no-watchman']);
+  expect(stderr).toContain('Test Suites: 1 passed, 1 total');
+  expect(stdout).toEqual('');
+  expect(exitCode).toEqual(0);
+});

packages/jest-haste-map/src/crawlers/__tests__/node.test.js

@@ -118,8 +118,13 @@ describe('node crawler', () => {
       expect(childProcess.spawn).lastCalledWith('find', [
         '/project/fruits',
         '/project/vegtables',
+        '(',
         '-type',
         'f',
+        '-o',
+        '-type',
+        'l',
+        ')',
         '(',
         '-iname',
         '*.js',

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

@@ -84,7 +84,8 @@ function findNative(
   callback: Callback,
 ): void {
   const args = Array.from(roots);
-  args.push('-type', 'f');
+  args.push('(', '-type', 'f', '-o', '-type', 'l', ')');
+
   if (extensions.length) {
     args.push('(');
   }
@@ -121,7 +122,8 @@ function findNative(
     } else {
       lines.forEach(path => {
         fs.stat(path, (err, stat) => {
-          if (!err && stat) {
+          // Filter out symlinks that describe directories
+          if (!err && stat && !stat.isDirectory()) {
             result.push([path, stat.mtime.getTime(), stat.size]);
           }
           if (--count === 0) {