diff --git a/core/modules/page_cache/src/Tests/PageCacheTest.php b/core/modules/page_cache/src/Tests/PageCacheTest.php
index a00416c..b21a4b1 100644
--- a/core/modules/page_cache/src/Tests/PageCacheTest.php
+++ b/core/modules/page_cache/src/Tests/PageCacheTest.php
@@ -254,34 +254,19 @@ public function testPageCacheWithoutVaryCookie() {
    * Test the setting of forms to be immutable.
    */
   public function testFormImmutability() {
-    // Install the module that provide sthe test form.
+    // Install the module that provides the test form.
     $this->container->get('module_installer')
       ->install(['page_cache_form_test']);
 
-    $verify_immutable_flag = function ($request_method, $immutable_flag_exists) {
-      // Mock a request.
-      $request = Request::create($this->buildUrl(''));
-      $request->setMethod($request_method);
-      $this->container->get('request_stack')->push($request);
+    $this->drupalGet('page_cache_form_test_immutability');
 
-      // Build a form while the page_cache module is enabled, , the
-      $form_state = new FormState();
-      \Drupal::formBuilder()
-        ->buildForm('\Drupal\page_cache_form_test\Form\TestForm', $form_state);
+    $this->assertText("Immutable: TRUE", "Form is immutable.");
 
-      $this->assertIdentical($immutable_flag_exists, array_key_exists('immutable', $form_state->getBuildInfo()));
-      if ($immutable_flag_exists) {
-        $this->assertIdentical($form_state->getBuildInfo()['immutable'], TRUE);
-      }
-    };
+    // Uninstall the page_cache module, verify the flag is not set.
+    $this->container->get('module_installer')->uninstall(['page_cache']);
 
-    // Verify the immutable flag is being set on cacheable requests.
-    $verify_immutable_flag('POST', FALSE);
-    $verify_immutable_flag('GET', TRUE);
+    $this->drupalGet('page_cache_form_test_immutability');
 
-    // Uninstall the page_cache module, verify the flag is never set.
-    $this->container->get('module_installer')->uninstall(['page_cache']);
-    $verify_immutable_flag('POST', FALSE);
-    $verify_immutable_flag('GET', FALSE);
+    $this->assertText("Immutable: FALSE", "Form is not immutable,");
   }
 }
diff --git a/core/modules/page_cache/tests/modules/page_cache_form_test.module b/core/modules/page_cache/tests/modules/page_cache_form_test.module
new file mode 100644
index 0000000..5cd2b15
--- /dev/null
+++ b/core/modules/page_cache/tests/modules/page_cache_form_test.module
@@ -0,0 +1,20 @@
+<?php
+
+/**
+ * @file
+ * Provides functionality for testing form caching
+ */
+
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+* Implements hook_form_FORM_ID_alter().
+*/
+function page_cache_form_test_form_page_cache_form_test_alter(&$form, FormStateInterface $form_state, $form_id) {
+  if (isset($form_state->getBuildInfo()['immutable']) && $form_state->getBuildInfo()['immutable']) {
+    $form['#suffix'] = 'Immutable: TRUE';
+  }
+  else {
+    $form['#suffix'] = 'Immutable: FALSE';
+  }
+}
\ No newline at end of file
diff --git a/core/modules/page_cache/tests/modules/page_cache_form_test.routing.yml b/core/modules/page_cache/tests/modules/page_cache_form_test.routing.yml
new file mode 100644
index 0000000..d28f166
--- /dev/null
+++ b/core/modules/page_cache/tests/modules/page_cache_form_test.routing.yml
@@ -0,0 +1,6 @@
+page_cache_form_test.test_immutability:
+  path: '/page_cache_form_test_immutability'
+  defaults:
+    _form: '\Drupal\page_cache_form_test\Form\TestForm'
+  requirements:
+    _access: 'TRUE'
\ No newline at end of file