--- /dev/null
+<?php
+
+namespace Drupal\Tests\system\Functional\Cache;
+
+use Drupal\Core\Cache\Cache;
+use Drupal\Core\Url;
+
+/**
+ * Provides test assertions for testing page-level cache contexts & tags.
+ *
+ * Can be used by test classes that extend \Drupal\Tests\BrowserTestBase.
+ */
+trait AssertPageCacheContextsAndTagsTrait {
+
+ /**
+ * Enables page caching.
+ */
+ protected function enablePageCaching() {
+ $config = $this->config('system.performance');
+ $config->set('cache.page.max_age', 300);
+ $config->save();
+ }
+
+ /**
+ * Gets a specific header value as array.
+ *
+ * @param string $header_name
+ * The header name.
+ *
+ * @return string[]
+ * The header value, potentially exploded by spaces.
+ */
+ protected function getCacheHeaderValues($header_name) {
+ $header_value = $this->drupalGetHeader($header_name);
+ if (empty($header_value)) {
+ return [];
+ }
+ else {
+ return explode(' ', $header_value);
+ }
+ }
+
+ /**
+ * Asserts whether an expected cache context was present in the last response.
+ *
+ * @param string $expected_cache_context
+ * The expected cache context.
+ */
+ protected function assertCacheContext($expected_cache_context) {
+ $cache_contexts = explode(' ', $this->drupalGetHeader('X-Drupal-Cache-Contexts'));
+ $this->assertTrue(in_array($expected_cache_context, $cache_contexts), "'" . $expected_cache_context . "' is present in the X-Drupal-Cache-Contexts header.");
+ }
+
+ /**
+ * Asserts that a cache context was not present in the last response.
+ *
+ * @param string $not_expected_cache_context
+ * The expected cache context.
+ */
+ protected function assertNoCacheContext($not_expected_cache_context) {
+ $cache_contexts = explode(' ', $this->drupalGetHeader('X-Drupal-Cache-Contexts'));
+ $this->assertFalse(in_array($not_expected_cache_context, $cache_contexts), "'" . $not_expected_cache_context . "' is not present in the X-Drupal-Cache-Contexts header.");
+ }
+
+ /**
+ * Asserts page cache miss, then hit for the given URL; checks cache headers.
+ *
+ * @param \Drupal\Core\Url $url
+ * The URL to test.
+ * @param string[] $expected_contexts
+ * The expected cache contexts for the given URL.
+ * @param string[] $expected_tags
+ * The expected cache tags for the given URL.
+ */
+ protected function assertPageCacheContextsAndTags(Url $url, array $expected_contexts, array $expected_tags) {
+ $absolute_url = $url->setAbsolute()->toString();
+ sort($expected_contexts);
+ sort($expected_tags);
+
+ // Assert cache miss + expected cache contexts + tags.
+ $this->drupalGet($absolute_url);
+ $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), 'MISS');
+ $this->assertCacheTags($expected_tags);
+ $this->assertCacheContexts($expected_contexts);
+
+ // Assert cache hit + expected cache contexts + tags.
+ $this->drupalGet($absolute_url);
+ $this->assertCacheTags($expected_tags);
+ $this->assertCacheContexts($expected_contexts);
+
+ // Assert page cache item + expected cache tags.
+ $cid_parts = [$url->setAbsolute()->toString(), 'html'];
+ $cid = implode(':', $cid_parts);
+ $cache_entry = \Drupal::cache('page')->get($cid);
+ sort($cache_entry->tags);
+ $this->assertEqual($cache_entry->tags, $expected_tags);
+ $this->debugCacheTags($cache_entry->tags, $expected_tags);
+ }
+
+ /**
+ * Provides debug information for cache tags.
+ *
+ * @param string[] $actual_tags
+ * The actual cache tags.
+ * @param string[] $expected_tags
+ * The expected cache tags.
+ */
+ protected function debugCacheTags(array $actual_tags, array $expected_tags) {
+ if ($actual_tags !== $expected_tags) {
+ debug('Unwanted cache tags in response: ' . implode(',', array_diff($actual_tags, $expected_tags)));
+ debug('Missing cache tags in response: ' . implode(',', array_diff($expected_tags, $actual_tags)));
+ }
+ }
+
+ /**
+ * Ensures that some cache tags are present in the current response.
+ *
+ * @param string[] $expected_tags
+ * The expected tags.
+ * @param bool $include_default_tags
+ * (optional) Whether the default cache tags should be included.
+ */
+ protected function assertCacheTags(array $expected_tags, $include_default_tags = TRUE) {
+ // The anonymous role cache tag is only added if the user is anonymous.
+ if ($include_default_tags) {
+ if (\Drupal::currentUser()->isAnonymous()) {
+ $expected_tags = Cache::mergeTags($expected_tags, ['config:user.role.anonymous']);
+ }
+ $expected_tags[] = 'http_response';
+ }
+ $actual_tags = $this->getCacheHeaderValues('X-Drupal-Cache-Tags');
+ $expected_tags = array_unique($expected_tags);
+ sort($expected_tags);
+ sort($actual_tags);
+ $this->assertIdentical($actual_tags, $expected_tags);
+ $this->debugCacheTags($actual_tags, $expected_tags);
+ }
+
+ /**
+ * Ensures that some cache contexts are present in the current response.
+ *
+ * @param string[] $expected_contexts
+ * The expected cache contexts.
+ * @param string $message
+ * (optional) A verbose message to output.
+ * @param bool $include_default_contexts
+ * (optional) Whether the default contexts should automatically be included.
+ *
+ * @return bool
+ * TRUE if the assertion succeeded, FALSE otherwise.
+ */
+ protected function assertCacheContexts(array $expected_contexts, $message = NULL, $include_default_contexts = TRUE) {
+ if ($include_default_contexts) {
+ $default_contexts = ['languages:language_interface', 'theme'];
+ // Add the user.permission context to the list of default contexts except
+ // when user is already there.
+ if (!in_array('user', $expected_contexts)) {
+ $default_contexts[] = 'user.permissions';
+ }
+ $expected_contexts = Cache::mergeContexts($expected_contexts, $default_contexts);
+ }
+
+ $actual_contexts = $this->getCacheHeaderValues('X-Drupal-Cache-Contexts');
+ sort($expected_contexts);
+ sort($actual_contexts);
+ $match = $actual_contexts === $expected_contexts;
+ if (!$match) {
+ debug('Unwanted cache contexts in response: ' . implode(',', array_diff($actual_contexts, $expected_contexts)));
+ debug('Missing cache contexts in response: ' . implode(',', array_diff($expected_contexts, $actual_contexts)));
+ }
+
+ $this->assertIdentical($actual_contexts, $expected_contexts, $message);
+
+ // For compatibility with both BrowserTestBase and WebTestBase always return
+ // a boolean.
+ return $match;
+ }
+
+ /**
+ * Asserts the max age header.
+ *
+ * @param int $max_age
+ */
+ protected function assertCacheMaxAge($max_age) {
+ $cache_control_header = $this->drupalGetHeader('Cache-Control');
+ if (strpos($cache_control_header, 'max-age:' . $max_age) === FALSE) {
+ debug('Expected max-age:' . $max_age . '; Response max-age:' . $cache_control_header);
+ }
+ $this->assertTrue(strpos($cache_control_header, 'max-age:' . $max_age));
+ }
+
+}