Issue #3262359: Don't catalog event subscribers as a way of determining the validity of stored results

tests/src/Kernel/ReadinessValidation/ReadinessValidationManagerTest.php

@@ -59,9 +59,9 @@ class ReadinessValidationManagerTest extends AutomaticUpdatesKernelTestBase {
     // Rebuild the container to trigger the service to be altered.
     $kernel = $this->container->get('kernel');
     $this->container = $kernel->rebuildContainer();
-    // Confirm that results will be NULL if the run() is not called again
-    // because the readiness checker services order has been altered.
-    $this->assertNull($this->getResultsFromManager());
+    // The stored results should be returned, even though the validators' order
+    // has been changed and the container has been rebuilt.
+    $this->assertValidationResultsEqual($expected_results_all, $this->getResultsFromManager());
     // Confirm that after calling run() the expected results order has changed.
     $expected_results_all_reversed = array_reverse($expected_results_all);
     $this->assertCheckerResultsFromManager($expected_results_all_reversed, TRUE);