--- /dev/null
+<?php
+
+namespace Drupal\system\Tests\Form;
+
+use Drupal\simpletest\WebTestBase;
+
+/**
+ * Tests form storage from cached pages.
+ *
+ * @group Form
+ */
+class FormStoragePageCacheTest extends WebTestBase {
+
+ /**
+ * @var array
+ */
+ public static $modules = ['form_test'];
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function setUp() {
+ parent::setUp();
+
+ $config = $this->config('system.performance');
+ $config->set('cache.page.max_age', 300);
+ $config->save();
+ }
+
+ /**
+ * Return the build id of the current form.
+ */
+ protected function getFormBuildId() {
+ $build_id_fields = $this->xpath('//input[@name="form_build_id"]');
+ $this->assertEqual(count($build_id_fields), 1, 'One form build id field on the page');
+ return (string) $build_id_fields[0]['value'];
+ }
+
+ /**
+ * Build-id is regenerated when validating cached form.
+ */
+ public function testValidateFormStorageOnCachedPage() {
+ $this->drupalGet('form-test/form-storage-page-cache');
+ $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'MISS', 'Page was not cached.');
+ $this->assertText('No old build id', 'No old build id on the page');
+ $build_id_initial = $this->getFormBuildId();
+
+ // Trigger validation error by submitting an empty title.
+ $edit = ['title' => ''];
+ $this->drupalPostForm(NULL, $edit, 'Save');
+ $this->assertText('No old build id', 'No old build id on the page');
+ $build_id_first_validation = $this->getFormBuildId();
+ $this->assertNotEqual($build_id_initial, $build_id_first_validation, 'Build id changes when form validation fails');
+
+ // Trigger validation error by again submitting an empty title.
+ $edit = ['title' => ''];
+ $this->drupalPostForm(NULL, $edit, 'Save');
+ $this->assertText('No old build id', 'No old build id on the page');
+ $build_id_second_validation = $this->getFormBuildId();
+ $this->assertEqual($build_id_first_validation, $build_id_second_validation, 'Build id remains the same when form validation fails subsequently');
+
+ // Repeat the test sequence but this time with a page loaded from the cache.
+ $this->drupalGet('form-test/form-storage-page-cache');
+ $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'HIT', 'Page was cached.');
+ $this->assertText('No old build id', 'No old build id on the page');
+ $build_id_from_cache_initial = $this->getFormBuildId();
+ $this->assertEqual($build_id_initial, $build_id_from_cache_initial, 'Build id is the same as on the first request');
+
+ // Trigger validation error by submitting an empty title.
+ $edit = ['title' => ''];
+ $this->drupalPostForm(NULL, $edit, 'Save');
+ $this->assertText('No old build id', 'No old build id on the page');
+ $build_id_from_cache_first_validation = $this->getFormBuildId();
+ $this->assertNotEqual($build_id_initial, $build_id_from_cache_first_validation, 'Build id changes when form validation fails');
+ $this->assertNotEqual($build_id_first_validation, $build_id_from_cache_first_validation, 'Build id from first user is not reused');
+
+ // Trigger validation error by again submitting an empty title.
+ $edit = ['title' => ''];
+ $this->drupalPostForm(NULL, $edit, 'Save');
+ $this->assertText('No old build id', 'No old build id on the page');
+ $build_id_from_cache_second_validation = $this->getFormBuildId();
+ $this->assertEqual($build_id_from_cache_first_validation, $build_id_from_cache_second_validation, 'Build id remains the same when form validation fails subsequently');
+ }
+
+ /**
+ * Build-id is regenerated when rebuilding cached form.
+ */
+ public function testRebuildFormStorageOnCachedPage() {
+ $this->drupalGet('form-test/form-storage-page-cache');
+ $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'MISS', 'Page was not cached.');
+ $this->assertText('No old build id', 'No old build id on the page');
+ $build_id_initial = $this->getFormBuildId();
+
+ // Trigger rebuild, should regenerate build id. When a submit handler
+ // triggers a rebuild, the form is built twice in the same POST request,
+ // and during the second build, there is an old build ID, but because the
+ // form is not cached during the initial GET request, it is different from
+ // that initial build ID.
+ $edit = ['title' => 'something'];
+ $this->drupalPostForm(NULL, $edit, 'Rebuild');
+ $this->assertNoText('No old build id', 'There is no old build id on the page.');
+ $this->assertNoText($build_id_initial, 'The old build id is not the initial build id.');
+ $build_id_first_rebuild = $this->getFormBuildId();
+ $this->assertNotEqual($build_id_initial, $build_id_first_rebuild, 'Build id changes on first rebuild.');
+
+ // Trigger subsequent rebuild, should regenerate the build id again.
+ $edit = ['title' => 'something'];
+ $this->drupalPostForm(NULL, $edit, 'Rebuild');
+ $this->assertText($build_id_first_rebuild, 'First build id as old build id on the page');
+ $build_id_second_rebuild = $this->getFormBuildId();
+ $this->assertNotEqual($build_id_first_rebuild, $build_id_second_rebuild, 'Build id changes on second rebuild.');
+ }
+
+}