diff -u b/core/modules/system/tests/src/FunctionalJavascript/ModuleFilterTest.php b/core/modules/system/tests/src/FunctionalJavascript/ModuleFilterTest.php
--- b/core/modules/system/tests/src/FunctionalJavascript/ModuleFilterTest.php
+++ b/core/modules/system/tests/src/FunctionalJavascript/ModuleFilterTest.php
@@ -30,9 +30,11 @@
 
     // Find the module filter field.
     $this->drupalGet('admin/modules');
-    $session = $this->assertSession();
-    $session->statusCodeEquals(200);
-    $page = $this->getSession()->getPage();
+    $assertSession = $this->assertSession();
+    $assertSession->statusCodeEquals(200);
+    $session = $this->getSession();
+    $page = $session->getPage();
+
     $filter = $page->findField('edit-text');
 
     // Get all module rows, for assertions later.
@@ -40,28 +42,31 @@
 
     // Test module filter reduces the number of visible rows.
     $filter->setValue('test');
-    $this->getSession()->wait(1000);
+    $session->wait(1000, 'jQuery("#module-node:visible").length == 0');
     $visible_rows = $this->filterVisibleElements($module_rows);
     self::assertNotEquals(count($module_rows), count($visible_rows));
 
     // Test Drupal.announce() message when multiple matches are expected.
     $expected_message = count($visible_rows) . ' modules are available in the modified list.';
-    $this->assertSession()->elementTextContains('css', '#drupal-live-announce', $expected_message);
+    $assertSession->elementTextContains('css', '#drupal-live-announce', $expected_message);
 
     // Test Drupal.announce() message only one match is expected.
     // Using a very specific module name, we expect only one row.
     $filter->setValue('System dependency test');
-    $this->getSession()->wait(1000);
+    $session->wait(1000, 'jQuery("#module-node:visible").length == 0');
     $visible_rows = $this->filterVisibleElements($module_rows);
+    self::assertEquals(1, count($visible_rows));
     $expected_message = '1 module is available in the modified list.';
-    $this->assertSession()->elementTextContains('css', '#drupal-live-announce', $expected_message);
+    $assertSession->elementTextContains('css', '#drupal-live-announce', $expected_message);
 
     // Test Drupal.announce() message when no matches are expected.
     $filter->setValue('Pan-Galactic Gargle Blaster');
-    $this->getSession()->wait(1000);
+    $session->wait(1000, 'jQuery("#module-node:visible").length == 0');
     $visible_rows = $this->filterVisibleElements($module_rows);
+    self::assertEquals(0, count($visible_rows));
+
     $expected_message = '0 modules are available in the modified list.';
-    $this->assertSession()->elementTextContains('css', '#drupal-live-announce', $expected_message);
+    $assertSession->elementTextContains('css', '#drupal-live-announce', $expected_message);
   }
 
   /**