Lock the fixture directory itself, so workers with their own TMPDIR share the lock

src/Testing/PHPUnit/AbstractRectorTestCase.php

@@ -298,37 +298,23 @@ private function lockFixtureDirectory(string $directory): void
         // a test can call doTestFile() more than once; a second lock from this process would wait for the first
         $this->unlockFixtureDirectory();
 
-        $lockFilePath = $this->createFixtureDirectoryLockFilePath($directory);
+        // PHP cannot open a directory on Windows
+        if ($this->isWindows()) {
+            return;
+        }
 
-        $fixtureDirectoryLock = fopen($lockFilePath, 'c');
+        // lock the directory itself: a lock file in sys_get_temp_dir() is not shared by test runners
+        // that give each worker its own TMPDIR, like fast-unit
+        $fixtureDirectoryLock = fopen($directory, 'r');
 
         if ($fixtureDirectoryLock === false) {
-            throw new ShouldNotHappenException('Cannot open the lock file ' . $lockFilePath);
+            throw new ShouldNotHappenException('Cannot open the fixture directory ' . $directory);
         }
 
         flock($fixtureDirectoryLock, LOCK_EX);
         $this->fixtureDirectoryLock = $fixtureDirectoryLock;
     }
 
-    /**
-     * The lock file lives in a directory in the system temp directory, so a project that tests its own rules gets no file in its fixture directories.
-     * The lock file is never deleted: a process waiting on a deleted file would hold a lock no other process sees.
-     */
-    private function createFixtureDirectoryLockFilePath(string $directory): string
-    {
-        $realDirectory = realpath($directory);
-
-        if ($realDirectory === false) {
-            $realDirectory = $directory;
-        }
-
-        $lockDirectory = sys_get_temp_dir() . '/rector_fixture_lock';
-
-        FileSystem::createDir($lockDirectory);
-
-        return $lockDirectory . '/' . sha1($realDirectory) . '.lock';
-    }
-
     private function unlockFixtureDirectory(): void
     {
         if (! is_resource($this->fixtureDirectoryLock)) {

tests/Testing/FixtureDirectoryLock/FixtureDirectoryLockTest.php

@@ -15,6 +15,23 @@ public function testDoesNotWriteLockFileIntoFixtureDirectory(): void
         $this->assertFileDoesNotExist(__DIR__ . '/Fixture/.fixture.lock');
     }
 
+    public function testLocksFixtureDirectoryWhateverTheTempDirectory(): void
+    {
+        if ($this->isWindows()) {
+            $this->markTestSkipped('PHP cannot open a directory on Windows');
+        }
+
+        $this->doTestFile(__DIR__ . '/Fixture/some_function.php.inc');
+
+        // a worker with its own TMPDIR opens the same directory, so it must see the lock
+        $otherProcessHandle = fopen(__DIR__ . '/Fixture', 'r');
+        $this->assertNotFalse($otherProcessHandle);
+
+        $this->assertFalse(flock($otherProcessHandle, LOCK_EX | LOCK_NB));
+
+        fclose($otherProcessHandle);
+    }
+
     public function provideConfigFilePath(): string
     {
         return __DIR__ . '/config/configured_rule.php';