diff --git a/tests/src/FunctionalJavascript/SiteAlertCacheWorkaroundTest.php b/tests/src/FunctionalJavascript/SiteAlertCacheWorkaroundTest.php
index 545dba8..52b95e2 100644
--- a/tests/src/FunctionalJavascript/SiteAlertCacheWorkaroundTest.php
+++ b/tests/src/FunctionalJavascript/SiteAlertCacheWorkaroundTest.php
@@ -60,8 +60,14 @@ class SiteAlertCacheWorkaroundTest extends SiteAlertWebDriverTestBase {
     // responsible for refreshing the alerts should be loaded in the page.
     $this->assertJavaScriptPresent();
 
-    // Check that the alert appears within a few seconds. Thanks to the
-    // workaround this will work regardless of the fact that the page is cached.
+    // The automatic refreshing has been disabled by setting the 'timeout' to 0,
+    // so the scheduled alert should not appear until we reload the page.
+    $this->assertSiteAlertNotAppears('Scheduled alert', 3000);
+
+    // Reload the page. Thanks to the workaround the site alert should now
+    // appear regardless of the fact that the page was cached at a moment when
+    // no alert was visible.
+    $this->drupalGet('<front>');
     $this->assertSiteAlertAppears('Scheduled alert');
 
     // Disable the alert. Now there are no more scheduled alerts, so the
diff --git a/tests/src/FunctionalJavascript/SiteAlertWebDriverTestBase.php b/tests/src/FunctionalJavascript/SiteAlertWebDriverTestBase.php
index fa19ff1..225b5f1 100644
--- a/tests/src/FunctionalJavascript/SiteAlertWebDriverTestBase.php
+++ b/tests/src/FunctionalJavascript/SiteAlertWebDriverTestBase.php
@@ -3,6 +3,7 @@
 namespace Drupal\Tests\site_alert\FunctionalJavascript;
 
 use Drupal\FunctionalJavascriptTests\WebDriverTestBase;
+use PHPUnit\Framework\AssertionFailedError;
 
 /**
  * Base class for functional JS tests for the Site Alerts module.
@@ -44,6 +45,27 @@ abstract class SiteAlertWebDriverTestBase extends WebDriverTestBase {
     $this->assertJsCondition($condition);
   }
 
+  /**
+   * Checks that the alert with the given message does not appear on the page.
+   *
+   * @param string $message
+   *   The message contained in the alert that is expected to appear.
+   * @param int $timeout
+   *   (Optional) Timeout in milliseconds, defaults to 10000.
+   */
+  protected function assertSiteAlertNotAppears($message, $timeout = 10000) {
+    $condition = 'jQuery(\'.site-alert div.text:contains("' . $message . '")\').length > 0;';
+    try {
+      $this->assertJsCondition($condition, $timeout);
+    }
+    catch (AssertionFailedError $e) {
+      // The alert has not appeared, the test has passed.
+      return;
+    }
+    // The alert has unexpectedly appeared, the test has failed.
+    $this->fail();
+  }
+
   /**
    * Checks that the alert with the given message disappears from the page.
    *