Issue #3344127: Composer validate all fixture manipulation changes

package_manager/tests/modules/fixture_manipulator/src/FixtureManipulator.php

@@ -45,8 +45,9 @@ class FixtureManipulator {
    * Validate the fixtures still passes `composer validate`.
    */
   private function validateComposer(): void {
-    $process = new Process([
-      'composer',
+    /** @var \PhpTuf\ComposerStager\Domain\Service\ProcessRunner\ComposerRunnerInterface $runner */
+    $runner = \Drupal::service('PhpTuf\ComposerStager\Domain\Service\ProcessRunner\ComposerRunnerInterface');
+    $runner->run([
       'validate',
       // @todo Check the lock file in https://drupal.org/i/3343827.
       '--no-check-lock',
@@ -55,8 +56,8 @@ class FixtureManipulator {
       '--no-interaction',
       '--ansi',
       '--no-cache',
-    ], $this->dir);
-    $process->mustRun();
+      '--working-dir=' . $this->dir,
+    ]);
   }
 
   /**