Issue #3328234: Improve test DX *and* confidence: assert VFS state

package_manager/tests/src/Kernel/ComposerJsonExistsValidatorTest.php

@@ -36,7 +36,7 @@ class ComposerJsonExistsValidatorTest extends PackageManagerKernelTestBase {
    */
   public function testComposerRequirementDuringPreApply(): void {
     $result = ValidationResult::createError([
-      'No composer.json file can be found at vfs://root/active',
+      'No composer.json file can be found at ' . $this->container->get('package_manager.path_locator')->getProjectRoot(),
     ]);
     $this->addEventTestListener(function (): void {
       unlink($this->container->get('package_manager.path_locator')