POC: Speed optimize class-loading for levels tests

.github/workflows/tests-levels-matrix.php

@@ -0,0 +1,33 @@
+<?php
+
+$testList = shell_exec('php vendor/bin/phpunit --list-tests');
+
+if (!is_string($testList)) {
+	throw new RuntimeException('Error while listing tests');
+}
+
+$testFilters = [];
+foreach(explode("\n", $testList) as $line) {
+	$cleanedLine = trim($line, ' -');
+
+	if ($cleanedLine === '') {
+		continue;
+	}
+
+	if (
+		!str_contains($cleanedLine, 'PHPStan\Generics\GenericsIntegrationTest') &&
+		!str_contains($cleanedLine, 'PHPStan\Levels\LevelsIntegrationTest')
+	) {
+		continue;
+	}
+
+	$cleanedLine = str_replace('\\', '\\\\', $cleanedLine);
+
+	$testFilters[] = $cleanedLine;
+}
+
+if ($testFilters === []) {
+	throw new RuntimeException('No tests found');
+}
+
+echo json_encode($testFilters);

.github/workflows/tests.yml

@@ -98,11 +98,45 @@ jobs:
       - name: "Tests"
         run: "make tests-integration"
 
+  tests-levels-matrix:
+    name: "Determine levels tests matrix"
+    runs-on: ubuntu-latest
+    timeout-minutes: 60
+
+    steps:
+      - name: "Checkout"
+        uses: actions/checkout@v3
+
+      - name: "Install PHP"
+        uses: "shivammathur/setup-php@v2"
+        with:
+          coverage: "none"
+          php-version: "8.1"
+          tools: pecl
+          extensions: ds,mbstring
+          ini-file: development
+          ini-values: memory_limit=1G
+
+      - name: "Install dependencies"
+        run: "composer install --no-interaction --no-progress"
+
+      - id: set-matrix
+        run: echo "matrix=$(php .github/workflows/tests-levels-matrix.php)" >> $GITHUB_OUTPUT
+
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.matrix }}
+
   tests-levels:
+    needs: tests-levels-matrix
+
     name: "Levels tests"
     runs-on: ubuntu-latest
     timeout-minutes: 60
 
+    strategy:
+      matrix:
+        test-filter: "${{fromJson(needs.tests-levels-matrix.outputs.matrix)}}"
+
     steps:
       - name: "Checkout"
         uses: actions/checkout@v3
@@ -121,7 +155,7 @@ jobs:
         run: "composer install --no-interaction --no-progress"
 
       - name: "Tests"
-        run: "make tests-levels"
+        run: "php vendor/bin/phpunit --filter '${{ matrix.test-filter }}' --group levels"
 
   tests-old-phpunit:
     name: "Tests with old PHPUnit"

src/Reflection/BetterReflection/SourceLocator/ComposerJsonAndInstalledJsonSourceLocatorMaker.php

@@ -112,6 +112,7 @@ public function create(string $projectInstallationPath): ?SourceLocator
 		foreach ($classMapPaths as $classMapPath) {
 			if (is_dir($classMapPath)) {
 				$locators[] = $this->optimizedDirectorySourceLocatorRepository->getOrCreate($classMapPath);
+				continue;
 			}
 			if (!is_file($classMapPath)) {
 				continue;