Issue #3279064: Consolidate logic around test stages

package_manager/tests/src/Kernel/PackageManagerKernelTestBase.php

@@ -34,11 +34,11 @@ abstract class PackageManagerKernelTestBase extends KernelTestBase {
   /**
    * The test staging root.
    *
-   * This value must be set before create an test stage instance.
+   * This value must be set before creating a test stage instance.
    *
    * @var string
    *
-   * @see \Drupal\Tests\package_manager\Kernel\TestStageTrait::setStagingRoot()
+   * @see \Drupal\Tests\package_manager\Kernel\TestStageTrait::__construct()
    */
   public static $testStagingRoot;
 
@@ -257,13 +257,6 @@ trait TestStageTrait {
    */
   public function __construct(...$arguments) {
     parent::__construct(...$arguments);
-    $this->setStagingRoot();
-  }
-
-  /**
-   * Sets the staging root.
-   */
-  protected function setStagingRoot(): void {
     $mirror = new \ReflectionClass(Stage::class);
     $this->tempStore->set($mirror->getConstant('TEMPSTORE_STAGING_ROOT_KEY'), PackageManagerKernelTestBase::$testStagingRoot);
   }