Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/modules/system/src/Tests/Cache/ApcuBackendUnitTest.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\system\Tests\Cache\ApcuBackendUnitTest.
+ */
+
+namespace Drupal\system\Tests\Cache;
+
+use Drupal\Core\Cache\ApcuBackend;
+
+/**
+ * Tests the APCu cache backend.
+ *
+ * @group Cache
+ * @requires extension apc
+ */
+class ApcuBackendUnitTest extends GenericCacheBackendUnitTestBase {
+
+  protected function checkRequirements() {
+    $requirements = parent::checkRequirements();
+    if (!extension_loaded('apc')) {
+      $requirements[] = 'APC extension not found.';
+    }
+    else {
+      if (version_compare(phpversion('apc'), '3.1.1', '<')) {
+        $requirements[] = 'APC extension must be newer than 3.1.1 for APCIterator support.';
+      }
+      if (PHP_SAPI === 'cli' && !ini_get('apc.enable_cli')) {
+        $requirements[] = 'apc.enable_cli must be enabled to run this test.';
+      }
+    }
+    return $requirements;
+  }
+
+  protected function createCacheBackend($bin) {
+    return new ApcuBackend($bin, $this->databasePrefix, \Drupal::service('cache_tags.invalidator.checksum'));
+  }
+
+  protected function tearDown() {
+    foreach ($this->cachebackends as $bin => $cachebackend) {
+      $this->cachebackends[$bin]->removeBin();
+    }
+    parent::tearDown();
+  }
+
+}

core/modules/system/src/Tests/Cache/AssertPageCacheContextsAndTagsTrait.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\system\Tests\Cache\AssertPageCacheContextsAndTagsTrait.
+ */
+
+namespace Drupal\system\Tests\Cache;
+
+use Drupal\Core\Url;
+
+/**
+ * Provides test assertions for testing page-level cache contexts & tags.
+ *
+ * Can be used by test classes that extend \Drupal\simpletest\WebTestBase.
+ */
+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 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.
+    $cid_parts = array($url->setAbsolute()->toString(), 'html');
+    $cid = implode(':', $cid_parts);
+    $cache_entry = \Drupal::cache('render')->get($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 !== $expected_tags) {
+      debug('Missing cache tags: ' . implode(',', array_diff($expected_tags, $actual_tags)));
+      debug('Unwanted cache tags: ' . implode(',', array_diff($actual_tags, $expected_tags)));
+    }
+  }
+
+  /**
+   * Ensures that some cache tags are present in the current response.
+   *
+   * @param string[] $expected_tags
+   *   The expected tags.
+   */
+  protected function assertCacheTags(array $expected_tags) {
+    $actual_tags = $this->getCacheHeaderValues('X-Drupal-Cache-Tags');
+    sort($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.
+   *
+   * @return
+   *   TRUE if the assertion succeeded, FALSE otherwise.
+   */
+  protected function assertCacheContexts(array $expected_contexts, $message = NULL) {
+    $actual_contexts = $this->getCacheHeaderValues('X-Drupal-Cache-Contexts');
+    sort($expected_contexts);
+    sort($actual_contexts);
+    $return = $this->assertIdentical($actual_contexts, $expected_contexts, $message);
+    if (!$return) {
+      debug('Missing cache contexts: ' . implode(',', array_diff($actual_contexts, $expected_contexts)));
+      debug('Unwanted cache contexts: ' . implode(',', array_diff($expected_contexts, $actual_contexts)));
+    }
+    return $return;
+  }
+
+  /**
+   * 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));
+  }
+
+}

core/modules/system/src/Tests/Cache/BackendChainUnitTest.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\system\Tests\Cache\BackendChainUnitTest.
+ */
+
+namespace Drupal\system\Tests\Cache;
+
+use Drupal\Core\Cache\BackendChain;
+use Drupal\Core\Cache\MemoryBackend;
+
+/**
+ * Unit test of the backend chain using the generic cache unit test base.
+ *
+ * @group Cache
+ */
+class BackendChainUnitTest extends GenericCacheBackendUnitTestBase {
+
+  protected function createCacheBackend($bin) {
+    $chain = new BackendChain($bin);
+
+    // We need to create some various backends in the chain.
+    $chain
+      ->appendBackend(new MemoryBackend('foo'))
+      ->prependBackend(new MemoryBackend('bar'))
+      ->appendBackend(new MemoryBackend('baz'));
+
+    \Drupal::service('cache_tags.invalidator')->addInvalidator($chain);
+
+    return $chain;
+  }
+
+}

core/modules/system/src/Tests/Cache/CacheTestBase.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\system\Tests\Cache\CacheTestBase.
+ */
+
+namespace Drupal\system\Tests\Cache;
+
+use Drupal\simpletest\WebTestBase;
+
+/**
+ * Provides helper methods for cache tests.
+ */
+abstract class CacheTestBase extends WebTestBase {
+
+  protected $defaultBin = 'render';
+  protected $defaultCid = 'test_temporary';
+  protected $defaultValue = 'CacheTest';
+
+  /**
+   * Checks whether or not a cache entry exists.
+   *
+   * @param $cid
+   *   The cache id.
+   * @param $var
+   *   The variable the cache should contain.
+   * @param $bin
+   *   The bin the cache item was stored in.
+   * @return
+   *   TRUE on pass, FALSE on fail.
+   */
+  protected function checkCacheExists($cid, $var, $bin = NULL) {
+    if ($bin == NULL) {
+      $bin = $this->defaultBin;
+    }
+
+    $cached = \Drupal::cache($bin)->get($cid);
+
+    return isset($cached->data) && $cached->data == $var;
+  }
+
+  /**
+   * Asserts that a cache entry exists.
+   *
+   * @param $message
+   *   Message to display.
+   * @param $var
+   *   The variable the cache should contain.
+   * @param $cid
+   *   The cache id.
+   * @param $bin
+   *   The bin the cache item was stored in.
+   */
+  protected function assertCacheExists($message, $var = NULL, $cid = NULL, $bin = NULL) {
+    if ($bin == NULL) {
+      $bin = $this->defaultBin;
+    }
+    if ($cid == NULL) {
+      $cid = $this->defaultCid;
+    }
+    if ($var == NULL) {
+      $var = $this->defaultValue;
+    }
+
+    $this->assertTrue($this->checkCacheExists($cid, $var, $bin), $message);
+  }
+
+  /**
+   * Asserts that a cache entry has been removed.
+   *
+   * @param $message
+   *   Message to display.
+   * @param $cid
+   *   The cache id.
+   * @param $bin
+   *   The bin the cache item was stored in.
+   */
+  function assertCacheRemoved($message, $cid = NULL, $bin = NULL) {
+    if ($bin == NULL) {
+      $bin = $this->defaultBin;
+    }
+    if ($cid == NULL) {
+      $cid = $this->defaultCid;
+    }
+
+    $cached = \Drupal::cache($bin)->get($cid);
+    $this->assertFalse($cached, $message);
+  }
+}

core/modules/system/src/Tests/Cache/ChainedFastBackendUnitTest.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\system\Tests\Cache\ChainedFastBackendUnitTest.
+ */
+
+namespace Drupal\system\Tests\Cache;
+
+use Drupal\Core\Cache\ChainedFastBackend;
+use Drupal\Core\Cache\DatabaseBackend;
+use Drupal\Core\Cache\PhpBackend;
+
+/**
+ * Unit test of the fast chained backend using the generic cache unit test base.
+ *
+ * @group Cache
+ */
+class ChainedFastBackendUnitTest extends GenericCacheBackendUnitTestBase {
+
+  /**
+   * Creates a new instance of ChainedFastBackend.
+   *
+   * @return \Drupal\Core\Cache\ChainedFastBackend
+   *   A new ChainedFastBackend object.
+   */
+  protected function createCacheBackend($bin) {
+    $consistent_backend = new DatabaseBackend(\Drupal::service('database'), \Drupal::service('cache_tags.invalidator.checksum'), $bin);
+    $fast_backend = new PhpBackend($bin, \Drupal::service('cache_tags.invalidator.checksum'));
+    $backend = new ChainedFastBackend($consistent_backend, $fast_backend, $bin);
+    // Explicitly register the cache bin as it can not work through the
+    // cache bin list in the container.
+    \Drupal::service('cache_tags.invalidator')->addInvalidator($backend);
+    return $backend;
+  }
+
+}

core/modules/system/src/Tests/Cache/ClearTest.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\system\Tests\Cache\ClearTest.
+ */
+
+namespace Drupal\system\Tests\Cache;
+
+/**
+ * Tests our clearing is done the proper way.
+ *
+ * @group Cache
+ */
+use Drupal\Core\Cache\Cache;
+
+class ClearTest extends CacheTestBase {
+
+  protected function setUp() {
+    $this->defaultBin = 'render';
+    $this->defaultValue = $this->randomMachineName(10);
+
+    parent::setUp();
+  }
+
+  /**
+   * Tests drupal_flush_all_caches().
+   */
+  function testFlushAllCaches() {
+    // Create cache entries for each flushed cache bin.
+    $bins = Cache::getBins();
+    $this->assertTrue($bins, 'Cache::getBins() returned bins to flush.');
+    foreach ($bins as $bin => $cache_backend) {
+      $cid = 'test_cid_clear' . $bin;
+      $cache_backend->set($cid, $this->defaultValue);
+    }
+
+    // Remove all caches then make sure that they are cleared.
+    drupal_flush_all_caches();
+
+    foreach ($bins as $bin => $cache_backend) {
+      $cid = 'test_cid_clear' . $bin;
+      $this->assertFalse($this->checkCacheExists($cid, $this->defaultValue, $bin), format_string('All cache entries removed from @bin.', array('@bin' => $bin)));
+    }
+  }
+}

core/modules/system/src/Tests/Cache/DatabaseBackendTagTest.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\system\Tests\Cache\DatabaseBackendTagTest.
+ */
+
+namespace Drupal\system\Tests\Cache;
+
+use Drupal\Core\Cache\Cache;
+use Drupal\Core\DependencyInjection\ContainerBuilder;
+use Drupal\simpletest\KernelTestBase;
+use Symfony\Component\DependencyInjection\Reference;
+
+/**
+ * Tests DatabaseBackend cache tag implementation.
+ *
+ * @group Cache
+ */
+class DatabaseBackendTagTest extends KernelTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = array('system');
+
+  /**
+   * {@inheritdoc}
+   */
+  public function containerBuild(ContainerBuilder $container) {
+    parent::containerBuild($container);
+    // Change container to database cache backends.
+    $container
+      ->register('cache_factory', 'Drupal\Core\Cache\CacheFactory')
+      ->addArgument(new Reference('settings'))
+      ->addMethodCall('setContainer', array(new Reference('service_container')));
+  }
+
+  public function testTagInvalidations() {
+    // Create cache entry in multiple bins.
+    $tags = array('test_tag:1', 'test_tag:2', 'test_tag:3');
+    $bins = array('data', 'bootstrap', 'render');
+    foreach ($bins as $bin) {
+      $bin = \Drupal::cache($bin);
+      $bin->set('test', 'value', Cache::PERMANENT, $tags);
+      $this->assertTrue($bin->get('test'), 'Cache item was set in bin.');
+    }
+
+    $invalidations_before = intval(db_select('cachetags')->fields('cachetags', array('invalidations'))->condition('tag', 'test_tag:2')->execute()->fetchField());
+    Cache::invalidateTags(array('test_tag:2'));
+
+    // Test that cache entry has been invalidated in multiple bins.
+    foreach ($bins as $bin) {
+      $bin = \Drupal::cache($bin);
+      $this->assertFalse($bin->get('test'), 'Tag invalidation affected item in bin.');
+    }
+
+    // Test that only one tag invalidation has occurred.
+    $invalidations_after = intval(db_select('cachetags')->fields('cachetags', array('invalidations'))->condition('tag', 'test_tag:2')->execute()->fetchField());
+    $this->assertEqual($invalidations_after, $invalidations_before + 1, 'Only one addition cache tag invalidation has occurred after invalidating a tag used in multiple bins.');
+  }
+
+}

core/modules/system/src/Tests/Cache/DatabaseBackendUnitTest.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\system\Tests\Cache\DatabaseBackendUnitTest.
+ */
+
+namespace Drupal\system\Tests\Cache;
+
+use Drupal\Core\Cache\DatabaseBackend;
+
+/**
+ * Unit test of the database backend using the generic cache unit test base.
+ *
+ * @group Cache
+ */
+class DatabaseBackendUnitTest extends GenericCacheBackendUnitTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = array('system');
+
+  /**
+   * Creates a new instance of DatabaseBackend.
+   *
+   * @return
+   *   A new DatabaseBackend object.
+   */
+  protected function createCacheBackend($bin) {
+    return new DatabaseBackend($this->container->get('database'), $this->container->get('cache_tags.invalidator.checksum'), $bin);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function testSetGet() {
+    parent::testSetGet();
+    $backend = $this->getCacheBackend();
+
+    // Set up a cache ID that is not ASCII and longer than 255 characters so we
+    // can test cache ID normalization.
+    $cid_long = str_repeat('愛€', 500);
+    $cached_value_long = $this->randomMachineName();
+    $backend->set($cid_long, $cached_value_long);
+    $this->assertIdentical($cached_value_long, $backend->get($cid_long)->data, "Backend contains the correct value for long, non-ASCII cache id.");
+
+    $cid_short = '愛1€';
+    $cached_value_short = $this->randomMachineName();
+    $backend->set($cid_short, $cached_value_short);
+    $this->assertIdentical($cached_value_short, $backend->get($cid_short)->data, "Backend contains the correct value for short, non-ASCII cache id.");
+  }
+
+}

core/modules/system/src/Tests/Cache/GenericCacheBackendUnitTestBase.php

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+<?php
+
+/**
+ * @file
+ * Contains \Drupal\system\Tests\Cache\GenericCacheBackendUnitTestBase.
+ */
+
+namespace Drupal\system\Tests\Cache;
+
+use Drupal\Core\Cache\Cache;
+use Drupal\Core\Cache\CacheBackendInterface;
+use Drupal\simpletest\KernelTestBase;
+
+/**
+ * Tests any cache backend.
+ *
+ * Full generic unit test suite for any cache backend. In order to use it for a
+ * cache backend implementation, extend this class and override the
+ * createBackendInstance() method to return an object.
+ *
+ * @see DatabaseBackendUnitTestCase
+ *   For a full working implementation.
+ */
+abstract class GenericCacheBackendUnitTestBase extends KernelTestBase {
+
+  /**
+   * Array of objects implementing Drupal\Core\Cache\CacheBackendInterface.
+   *
+   * @var array
+   */
+  protected $cachebackends;
+
+  /**
+   * Cache bin to use for testing.
+   *
+   * @var string
+   */
+  protected $testBin;
+
+  /**
+   * Random value to use in tests.
+   *
+   * @var string
+   */
+  protected $defaultValue;
+
+  /**
+   * Gets the testing bin.
+   *
+   * Override this method if you want to work on a different bin than the
+   * default one.
+   *
+   * @return string
+   *   Bin name.
+   */
+  protected function getTestBin() {
+    if (!isset($this->testBin)) {
+      $this->testBin = 'page';
+    }
+    return $this->testBin;
+  }
+
+  /**
+   * Creates a cache backend to test.
+   *
+   * Override this method to test a CacheBackend.
+   *
+   * @param string $bin
+   *   Bin name to use for this backend instance.
+   *
+   * @return \Drupal\Core\Cache\CacheBackendInterface
+   *   Cache backend to test.
+   */
+  protected abstract function createCacheBackend($bin);
+
+  /**
+   * Allows specific implementation to change the environment before a test run.
+   */
+  public function setUpCacheBackend() {
+  }
+
+  /**
+   * Allows alteration of environment after a test run but before tear down.
+   *
+   * Used before the real tear down because the tear down will change things
+   * such as the database prefix.
+   */
+  public function tearDownCacheBackend() {
+  }
+
+  /**
+   * Gets a backend to test; this will get a shared instance set in the object.
+   *
+   * @return \Drupal\Core\Cache\CacheBackendInterface
+   *   Cache backend to test.
+   */
+  protected function getCacheBackend($bin = null) {
+    if (!isset($bin)) {
+      $bin = $this->getTestBin();
+    }
+    if (!isset($this->cachebackends[$bin])) {
+      $this->cachebackends[$bin] = $this->createCacheBackend($bin);
+      // Ensure the backend is empty.
+      $this->cachebackends[$bin]->deleteAll();
+    }
+    return $this->cachebackends[$bin];
+  }
+
+  protected function setUp() {
+    $this->cachebackends = array();
+    $this->defaultValue = $this->randomMachineName(10);
+
+    parent::setUp();
+
+    $this->setUpCacheBackend();
+  }
+
+  protected function tearDown() {
+    // Destruct the registered backend, each test will get a fresh instance,
+    // properly emptying it here ensure that on persistent data backends they
+    // will come up empty the next test.
+    foreach ($this->cachebackends as $bin => $cachebackend) {
+      $this->cachebackends[$bin]->deleteAll();
+    }
+    unset($this->cachebackends);
+
+    $this->tearDownCacheBackend();
+
+    parent::tearDown();
+  }
+
+  /**
+   * Tests the get and set methods of Drupal\Core\Cache\CacheBackendInterface.
+   */
+  public function testSetGet() {
+    $backend = $this->getCacheBackend();
+
+    $this->assertIdentical(FALSE, $backend->get('test1'), "Backend does not contain data for cache id test1.");
+    $with_backslash = array('foo' => '\Drupal\foo\Bar');
+    $backend->set('test1', $with_backslash);
+    $cached = $backend->get('test1');
+    $this->assert(is_object($cached), "Backend returned an object for cache id test1.");
+    $this->assertIdentical($with_backslash, $cached->data);
+    $this->assertTrue($cached->valid, 'Item is marked as valid.');
+    // We need to round because microtime may be rounded up in the backend.
+    $this->assertTrue($cached->created >= REQUEST_TIME && $cached->created <= round(microtime(TRUE), 3), 'Created time is correct.');
+    $this->assertEqual($cached->expire, Cache::PERMANENT, 'Expire time is correct.');
+
+    $this->assertIdentical(FALSE, $backend->get('test2'), "Backend does not contain data for cache id test2.");
+    $backend->set('test2', array('value' => 3), REQUEST_TIME + 3);
+    $cached = $backend->get('test2');
+    $this->assert(is_object($cached), "Backend returned an object for cache id test2.");
+    $this->assertIdentical(array('value' => 3), $cached->data);
+    $this->assertTrue($cached->valid, 'Item is marked as valid.');
+    $this->assertTrue($cached->created >= REQUEST_TIME && $cached->created <= round(microtime(TRUE), 3), 'Created time is correct.');
+    $this->assertEqual($cached->expire, REQUEST_TIME + 3, 'Expire time is correct.');
+
+    $backend->set('test3', 'foobar', REQUEST_TIME - 3);
+    $this->assertFalse($backend->get('test3'), 'Invalid item not returned.');
+    $cached = $backend->get('test3', TRUE);
+    $this->assert(is_object($cached), 'Backend returned an object for cache id test3.');
+    $this->assertFalse($cached->valid, 'Item is marked as valid.');
+    $this->assertTrue($cached->created >= REQUEST_TIME && $cached->created <= round(microtime(TRUE), 3), 'Created time is correct.');
+    $this->assertEqual($cached->expire, REQUEST_TIME - 3, 'Expire time is correct.');
+
+    $this->assertIdentical(FALSE, $backend->get('test4'), "Backend does not contain data for cache id test4.");
+    $with_eof = array('foo' => "\nEOF\ndata");
+    $backend->set('test4', $with_eof);
+    $cached = $backend->get('test4');
+    $this->assert(is_object($cached), "Backend returned an object for cache id test4.");
+    $this->assertIdentical($with_eof, $cached->data);
+    $this->assertTrue($cached->valid, 'Item is marked as valid.');
+    $this->assertTrue($cached->created >= REQUEST_TIME && $cached->created <= round(microtime(TRUE), 3), 'Created time is correct.');
+    $this->assertEqual($cached->expire, Cache::PERMANENT, 'Expire time is correct.');
+
+    $this->assertIdentical(FALSE, $backend->get('test5'), "Backend does not contain data for cache id test5.");
+    $with_eof_and_semicolon = array('foo' => "\nEOF;\ndata");
+    $backend->set('test5', $with_eof_and_semicolon);
+    $cached = $backend->get('test5');
+    $this->assert(is_object($cached), "Backend returned an object for cache id test5.");
+    $this->assertIdentical($with_eof_and_semicolon, $cached->data);
+    $this->assertTrue($cached->valid, 'Item is marked as valid.');
+    $this->assertTrue($cached->created >= REQUEST_TIME && $cached->created <= round(microtime(TRUE), 3), 'Created time is correct.');
+    $this->assertEqual($cached->expire, Cache::PERMANENT, 'Expire time is correct.');
+
+    $with_variable = array('foo' => '$bar');
+    $backend->set('test6', $with_variable);
+    $cached = $backend->get('test6');
+    $this->assert(is_object($cached), "Backend returned an object for cache id test6.");
+    $this->assertIdentical($with_variable, $cached->data);
+
+    // Make sure that a cached object is not affected by changing the original.
+    $data = new \stdClass();
+    $data->value = 1;
+    $data->obj = new \stdClass();
+    $data->obj->value = 2;
+    $backend->set('test7', $data);
+    $expected_data = clone $data;
+    // Add a property to the original. It should not appear in the cached data.
+    $data->this_should_not_be_in_the_cache = TRUE;
+    $cached = $backend->get('test7');
+    $this->assert(is_object($cached), "Backend returned an object for cache id test7.");
+    $this->assertEqual($expected_data, $cached->data);
+    $this->assertFalse(isset($cached->data->this_should_not_be_in_the_cache));
+    // Add a property to the cache data. It should not appear when we fetch
+    // the data from cache again.
+    $cached->data->this_should_not_be_in_the_cache = TRUE;
+    $fresh_cached = $backend->get('test7');
+    $this->assertFalse(isset($fresh_cached->data->this_should_not_be_in_the_cache));
+
+    // Check with a long key.
+    $cid = str_repeat('a', 300);
+    $backend->set($cid, 'test');
+    $this->assertEqual('test', $backend->get($cid)->data);
+
+    // Check that the cache key is case sensitive.
+    $backend->set('TEST8', 'value');
+    $this->assertEqual('value', $backend->get('TEST8')->data);
+    $this->assertFalse($backend->get('test8'));
+
+    // Calling ::set() with invalid cache tags.
+    try {
+      $backend->set('exception_test', 'value', Cache::PERMANENT, ['node' => [3, 5, 7]]);
+      $this->fail('::set() was called with invalid cache tags, no exception was thrown.');
+    }
+    catch (\LogicException $e) {
+      $this->pass('::set() was called with invalid cache tags, an exception was thrown.');
+    }
+  }
+
+  /**
+   * Tests Drupal\Core\Cache\CacheBackendInterface::delete().
+   */
+  public function testDelete() {
+    $backend = $this->getCacheBackend();
+
+    $this->assertIdentical(FALSE, $backend->get('test1'), "Backend does not contain data for cache id test1.");
+    $backend->set('test1', 7);
+    $this->assert(is_object($backend->get('test1')), "Backend returned an object for cache id test1.");
+
+    $this->assertIdentical(FALSE, $backend->get('test2'), "Backend does not contain data for cache id test2.");
+    $backend->set('test2', 3);
+    $this->assert(is_object($backend->get('test2')), "Backend returned an object for cache id %cid.");
+
+    $backend->delete('test1');
+    $this->assertIdentical(FALSE, $backend->get('test1'), "Backend does not contain data for cache id test1 after deletion.");
+
+    $this->assert(is_object($backend->get('test2')), "Backend still has an object for cache id test2.");
+
+    $backend->delete('test2');
+    $this->assertIdentical(FALSE, $backend->get('test2'), "Backend does not contain data for cache id test2 after deletion.");
+
+    $long_cid = str_repeat('a', 300);
+    $backend->set($long_cid, 'test');
+    $backend->delete($long_cid);
+    $this->assertIdentical(FALSE, $backend->get($long_cid), "Backend does not contain data for long cache id after deletion.");
+  }
+
+  /**
+   * Tests data type preservation.
+   */
+  public function testValueTypeIsKept() {
+    $backend = $this->getCacheBackend();
+
+    $variables = array(
+      'test1' => 1,
+      'test2' => '0',
+      'test3' => '',
+      'test4' => 12.64,
+      'test5' => FALSE,
+      'test6' => array(1,2,3),
+    );
+
+    // Create cache entries.
+    foreach ($variables as $cid => $data) {
+      $backend->set($cid, $data);
+    }
+
+    // Retrieve and test cache objects.
+    foreach ($variables as $cid => $value) {
+      $object = $backend->get($cid);
+      $this->assert(is_object($object), sprintf("Backend returned an object for cache id %s.", $cid));
+      $this->assertIdentical($value, $object->data, sprintf("Data of cached id %s kept is identical in type and value", $cid));
+    }
+  }
+
+  /**
+   * Tests Drupal\Core\Cache\CacheBackendInterface::getMultiple().
+   */
+  public function testGetMultiple() {
+    $backend = $this->getCacheBackend();
+
+    // Set numerous testing keys.
+    $long_cid = str_repeat('a', 300);
+    $backend->set('test1', 1);
+    $backend->set('test2', 3);
+    $backend->set('test3', 5);
+    $backend->set('test4', 7);
+    $backend->set('test5', 11);
+    $backend->set('test6', 13);
+    $backend->set('test7', 17);
+    $backend->set($long_cid, 300);
+
+    // Mismatch order for harder testing.
+    $reference = array(
+      'test3',
+      'test7',
+      'test21', // Cid does not exist.
+      'test6',
+      'test19', // Cid does not exist until added before second getMultiple().
+      'test2',
+    );
+
+    $cids = $reference;
+    $ret = $backend->getMultiple($cids);
+    // Test return - ensure it contains existing cache ids.
+    $this->assert(isset($ret['test2']), "Existing cache id test2 is set.");
+    $this->assert(isset($ret['test3']), "Existing cache id test3 is set.");
+    $this->assert(isset($ret['test6']), "Existing cache id test6 is set.");
+    $this->assert(isset($ret['test7']), "Existing cache id test7 is set.");
+    // Test return - ensure that objects has expected properties.
+    $this->assertTrue($ret['test2']->valid, 'Item is marked as valid.');
+    $this->assertTrue($ret['test2']->created >= REQUEST_TIME && $ret['test2']->created <= round(microtime(TRUE), 3), 'Created time is correct.');
+    $this->assertEqual($ret['test2']->expire, Cache::PERMANENT, 'Expire time is correct.');
+    // Test return - ensure it does not contain nonexistent cache ids.
+    $this->assertFalse(isset($ret['test19']), "Nonexistent cache id test19 is not set.");
+    $this->assertFalse(isset($ret['test21']), "Nonexistent cache id test21 is not set.");
+    // Test values.
+    $this->assertIdentical($ret['test2']->data, 3, "Existing cache id test2 has the correct value.");
+    $this->assertIdentical($ret['test3']->data, 5, "Existing cache id test3 has the correct value.");
+    $this->assertIdentical($ret['test6']->data, 13, "Existing cache id test6 has the correct value.");
+    $this->assertIdentical($ret['test7']->data, 17, "Existing cache id test7 has the correct value.");
+    // Test $cids array - ensure it contains cache id's that do not exist.
+    $this->assert(in_array('test19', $cids), "Nonexistent cache id test19 is in cids array.");
+    $this->assert(in_array('test21', $cids), "Nonexistent cache id test21 is in cids array.");
+    // Test $cids array - ensure it does not contain cache id's that exist.
+    $this->assertFalse(in_array('test2', $cids), "Existing cache id test2 is not in cids array.");
+    $this->assertFalse(in_array('test3', $cids), "Existing cache id test3 is not in cids array.");
+    $this->assertFalse(in_array('test6', $cids), "Existing cache id test6 is not in cids array.");
+    $this->assertFalse(in_array('test7', $cids), "Existing cache id test7 is not in cids array.");
+
+    // Test a second time after deleting and setting new keys which ensures that
+    // if the backend uses statics it does not cause unexpected results.
+    $backend->delete('test3');
+    $backend->delete('test6');
+    $backend->set('test19', 57);
+
+    $cids = $reference;
+    $ret = $backend->getMultiple($cids);
+    // Test return - ensure it contains existing cache ids.
+    $this->assert(isset($ret['test2']), "Existing cache id test2 is set");
+    $this->assert(isset($ret['test7']), "Existing cache id test7 is set");
+    $this->assert(isset($ret['test19']), "Added cache id test19 is set");
+    // Test return - ensure it does not contain nonexistent cache ids.
+    $this->assertFalse(isset($ret['test3']), "Deleted cache id test3 is not set");
+    $this->assertFalse(isset($ret['test6']), "Deleted cache id test6 is not set");
+    $this->assertFalse(isset($ret['test21']), "Nonexistent cache id test21 is not set");
+    // Test values.
+    $this->assertIdentical($ret['test2']->data, 3, "Existing cache id test2 has the correct value.");
+    $this->assertIdentical($ret['test7']->data, 17, "Existing cache id test7 has the correct value.");
+    $this->assertIdentical($ret['test19']->data, 57, "Added cache id test19 has the correct value.");
+    // Test $cids array - ensure it contains cache id's that do not exist.
+    $this->assert(in_array('test3', $cids), "Deleted cache id test3 is in cids array.");
+    $this->assert(in_array('test6', $cids), "Deleted cache id test6 is in cids array.");
+    $this->assert(in_array('test21', $cids), "Nonexistent cache id test21 is in cids array.");
+    // Test $cids array - ensure it does not contain cache id's that exist.
+    $this->assertFalse(in_array('test2', $cids), "Existing cache id test2 is not in cids array.");
+    $this->assertFalse(in_array('test7', $cids), "Existing cache id test7 is not in cids array.");
+    $this->assertFalse(in_array('test19', $cids), "Added cache id test19 is not in cids array.");
+
+    // Test with a long $cid and non-numeric array key.
+    $cids = array('key:key' => $long_cid);
+    $return = $backend->getMultiple($cids);
+    $this->assertEqual(300, $return[$long_cid]->data);
+    $this->assertTrue(empty($cids));
+  }
+
+  /**
+   * Tests \Drupal\Core\Cache\CacheBackendInterface::setMultiple().
+   */
+  public function testSetMultiple() {
+    $backend = $this->getCacheBackend();
+
+    $future_expiration = REQUEST_TIME + 100;
+
+    // Set multiple testing keys.
+    $backend->set('cid_1', 'Some other value');
+    $items = array(
+      'cid_1' => array('data' => 1),
+      'cid_2' => array('data' => 2),
+      'cid_3' => array('data' => array(1, 2)),
+      'cid_4' => array('data' => 1, 'expire' => $future_expiration),
+      'cid_5' => array('data' => 1, 'tags' => array('test:a', 'test:b')),
+    );
+    $backend->setMultiple($items);
+    $cids = array_keys($items);
+    $cached = $backend->getMultiple($cids);
+
+    $this->assertEqual($cached['cid_1']->data, $items['cid_1']['data'], 'Over-written cache item set correctly.');
+    $this->assertTrue($cached['cid_1']->valid, 'Item is marked as valid.');
+    $this->assertTrue($cached['cid_1']->created >= REQUEST_TIME && $cached['cid_1']->created <= round(microtime(TRUE), 3), 'Created time is correct.');
+    $this->assertEqual($cached['cid_1']->expire, CacheBackendInterface::CACHE_PERMANENT, 'Cache expiration defaults to permanent.');
+
+    $this->assertEqual($cached['cid_2']->data, $items['cid_2']['data'], 'New cache item set correctly.');
+    $this->assertEqual($cached['cid_2']->expire, CacheBackendInterface::CACHE_PERMANENT, 'Cache expiration defaults to permanent.');
+
+    $this->assertEqual($cached['cid_3']->data, $items['cid_3']['data'], 'New cache item with serialized data set correctly.');
+    $this->assertEqual($cached['cid_3']->expire, CacheBackendInterface::CACHE_PERMANENT, 'Cache expiration defaults to permanent.');
+
+    $this->assertEqual($cached['cid_4']->data, $items['cid_4']['data'], 'New cache item set correctly.');
+    $this->assertEqual($cached['cid_4']->expire, $future_expiration, 'Cache expiration has been correctly set.');
+
+    $this->assertEqual($cached['cid_5']->data, $items['cid_5']['data'], 'New cache item set correctly.');
+
+    // Calling ::setMultiple() with invalid cache tags.
+    try {
+      $items = [
+        'exception_test_1' => array('data' => 1, 'tags' => []),
+        'exception_test_2' => array('data' => 2, 'tags' => ['valid']),
+        'exception_test_3' => array('data' => 3, 'tags' => ['node' => [3, 5, 7]]),
+      ];
+      $backend->setMultiple($items);
+      $this->fail('::setMultiple() was called with invalid cache tags, no exception was thrown.');
+    }
+    catch (\LogicException $e) {
+      $this->pass('::setMultiple() was called with invalid cache tags, an exception was thrown.');
+    }
+  }
+
+  /**
+   * Test Drupal\Core\Cache\CacheBackendInterface::delete() and
+   * Drupal\Core\Cache\CacheBackendInterface::deleteMultiple().
+   */
+  public function testDeleteMultiple() {
+    $backend = $this->getCacheBackend();
+
+    // Set numerous testing keys.
+    $backend->set('test1', 1);
+    $backend->set('test2', 3);
+    $backend->set('test3', 5);
+    $backend->set('test4', 7);
+    $backend->set('test5', 11);
+    $backend->set('test6', 13);
+    $backend->set('test7', 17);
+
+    $backend->delete('test1');
+    $backend->delete('test23'); // Nonexistent key should not cause an error.
+    $backend->deleteMultiple(array(
+      'test3',
+      'test5',
+      'test7',
+      'test19', // Nonexistent key should not cause an error.
+      'test21', // Nonexistent key should not cause an error.
+    ));
+
+    // Test if expected keys have been deleted.
+    $this->assertIdentical(FALSE, $backend->get('test1'), "Cache id test1 deleted.");
+    $this->assertIdentical(FALSE, $backend->get('test3'), "Cache id test3 deleted.");
+    $this->assertIdentical(FALSE, $backend->get('test5'), "Cache id test5 deleted.");
+    $this->assertIdentical(FALSE, $backend->get('test7'), "Cache id test7 deleted.");
+
+    // Test if expected keys exist.
+    $this->assertNotIdentical(FALSE, $backend->get('test2'), "Cache id test2 exists.");
+    $this->assertNotIdentical(FALSE, $backend->get('test4'), "Cache id test4 exists.");
+    $this->assertNotIdentical(FALSE, $backend->get('test6'), "Cache id test6 exists.");
+
+    // Test if that expected keys do not exist.
+    $this->assertIdentical(FALSE, $backend->get('test19'), "Cache id test19 does not exist.");
+    $this->assertIdentical(FALSE, $backend->get('test21'), "Cache id test21 does not exist.");
+
+    // Calling deleteMultiple() with an empty array should not cause an error.
+    $this->assertFalse($backend->deleteMultiple(array()));
+  }
+
+  /**
+   * Test Drupal\Core\Cache\CacheBackendInterface::deleteAll().
+   */
+  public function testDeleteAll() {
+    $backend_a = $this->getCacheBackend();
+    $backend_b = $this->getCacheBackend('bootstrap');
+
+    // Set both expiring and permanent keys.
+    $backend_a->set('test1', 1, Cache::PERMANENT);
+    $backend_a->set('test2', 3, time() + 1000);
+    $backend_b->set('test3', 4, Cache::PERMANENT);
+
+    $backend_a->deleteAll();
+
+    $this->assertFalse($backend_a->get('test1'), 'First key has been deleted.');
+    $this->assertFalse($backend_a->get('test2'), 'Second key has been deleted.');
+    $this->assertTrue($backend_b->get('test3'), 'Item in other bin is preserved.');
+  }
+
+  /**
+   * Test Drupal\Core\Cache\CacheBackendInterface::invalidate() and
+   * Drupal\Core\Cache\CacheBackendInterface::invalidateMultiple().
+   */
+  function testInvalidate() {
+    $backend = $this->getCacheBackend();
+    $backend->set('test1', 1);
+    $backend->set('test2', 2);
+    $backend->set('test3', 2);
+    $backend->set('test4', 2);
+
+    $reference = array('test1', 'test2', 'test3', 'test4');
+
+    $cids = $reference;
+    $ret = $backend->getMultiple($cids);
+    $this->assertEqual(count($ret), 4, 'Four items returned.');
+
+    $backend->invalidate('test1');
+    $backend->invalidateMultiple(array('test2', 'test3'));
+
+    $cids = $reference;
+    $ret = $backend->getMultiple($cids);
+    $this->assertEqual(count($ret), 1, 'Only one item element returned.');
+
+    $cids = $reference;
+    $ret = $backend->getMultiple($cids, TRUE);
+    $this->assertEqual(count($ret), 4, 'Four items returned.');
+
+    // Calling invalidateMultiple() with an empty array should not cause an
+    // error.
+    $this->assertFalse($backend->invalidateMultiple(array()));
+  }
+
+  /**
+   * Tests Drupal\Core\Cache\CacheBackendInterface::invalidateTags().
+   */
+  function testInvalidateTags() {
+    $backend = $this->getCacheBackend();
+
+    // Create two cache entries with the same tag and tag value.
+    $backend->set('test_cid_invalidate1', $this->defaultValue, Cache::PERMANENT, array('test_tag:2'));
+    $backend->set('test_cid_invalidate2', $this->defaultValue, Cache::PERMANENT, array('test_tag:2'));
+    $this->assertTrue($backend->get('test_cid_invalidate1') && $backend->get('test_cid_invalidate2'), 'Two cache items were created.');
+
+    // Invalidate test_tag of value 1. This should invalidate both entries.
+    Cache::invalidateTags(array('test_tag:2'));
+    $this->assertFalse($backend->get('test_cid_invalidate1') || $backend->get('test_cid_invalidate2'), 'Two cache items invalidated after invalidating a cache tag.');
+    $this->assertTrue($backend->get('test_cid_invalidate1', TRUE) && $backend->get('test_cid_invalidate2', TRUE), 'Cache items not deleted after invalidating a cache tag.');
+
+    // Create two cache entries with the same tag and an array tag value.
+    $backend->set('test_cid_invalidate1', $this->defaultValue, Cache::PERMANENT, array('test_tag:1'));
+    $backend->set('test_cid_invalidate2', $this->defaultValue, Cache::PERMANENT, array('test_tag:1'));
+    $this->assertTrue($backend->get('test_cid_invalidate1') && $backend->get('test_cid_invalidate2'), 'Two cache items were created.');
+
+    // Invalidate test_tag of value 1. This should invalidate both entries.
+    Cache::invalidateTags(array('test_tag:1'));
+    $this->assertFalse($backend->get('test_cid_invalidate1') || $backend->get('test_cid_invalidate2'), 'Two caches removed after invalidating a cache tag.');
+    $this->assertTrue($backend->get('test_cid_invalidate1', TRUE) && $backend->get('test_cid_invalidate2', TRUE), 'Cache items not deleted after invalidating a cache tag.');
+
+    // Create three cache entries with a mix of tags and tag values.
+    $backend->set('test_cid_invalidate1', $this->defaultValue, Cache::PERMANENT, array('test_tag:1'));
+    $backend->set('test_cid_invalidate2', $this->defaultValue, Cache::PERMANENT, array('test_tag:2'));
+    $backend->set('test_cid_invalidate3', $this->defaultValue, Cache::PERMANENT, array('test_tag_foo:3'));
+    $this->assertTrue($backend->get('test_cid_invalidate1') && $backend->get('test_cid_invalidate2') && $backend->get('test_cid_invalidate3'), 'Three cached items were created.');
+    Cache::invalidateTags(array('test_tag_foo:3'));
+    $this->assertTrue($backend->get('test_cid_invalidate1') && $backend->get('test_cid_invalidate2'), 'Cache items not matching the tag were not invalidated.');
+    $this->assertFalse($backend->get('test_cid_invalidated3'), 'Cached item matching the tag was removed.');
+
+    // Create cache entry in multiple bins. Two cache entries
+    // (test_cid_invalidate1 and test_cid_invalidate2) still exist from previous
+    // tests.
+    $tags = array('test_tag:1', 'test_tag:2', 'test_tag:3');
+    $bins = array('path', 'bootstrap', 'page');
+    foreach ($bins as $bin) {
+      $this->getCacheBackend($bin)->set('test', $this->defaultValue, Cache::PERMANENT, $tags);
+      $this->assertTrue($this->getCacheBackend($bin)->get('test'), 'Cache item was set in bin.');
+    }
+
+    Cache::invalidateTags(array('test_tag:2'));
+
+    // Test that the cache entry has been invalidated in multiple bins.
+    foreach ($bins as $bin) {
+      $this->assertFalse($this->getCacheBackend($bin)->get('test'), 'Tag invalidation affected item in bin.');
+    }
+    // Test that the cache entry with a matching tag has been invalidated.
+    $this->assertFalse($this->getCacheBackend($bin)->get('test_cid_invalidate2'), 'Cache items matching tag were invalidated.');
+    // Test that the cache entry with without a matching tag still exists.
+    $this->assertTrue($this->getCacheBackend($bin)->get('test_cid_invalidate1'), 'Cache items not matching tag were not invalidated.');
+  }
+
+  /**
+   * Test Drupal\Core\Cache\CacheBackendInterface::invalidateAll().
+   */
+  public function testInvalidateAll() {
+    $backend_a = $this->getCacheBackend();
+    $backend_b = $this->getCacheBackend('bootstrap');
+
+    // Set both expiring and permanent keys.
+    $backend_a->set('test1', 1, Cache::PERMANENT);
+    $backend_a->set('test2', 3, time() + 1000);
+    $backend_b->set('test3', 4, Cache::PERMANENT);
+
+    $backend_a->invalidateAll();
+
+    $this->assertFalse($backend_a->get('test1'), 'First key has been invalidated.');
+    $this->assertFalse($backend_a->get('test2'), 'Second key has been invalidated.');
+    $this->assertTrue($backend_b->get('test3'), 'Item in other bin is preserved.');
+    $this->assertTrue($backend_a->get('test1', TRUE), 'First key has not been deleted.');
+    $this->assertTrue($backend_a->get('test2', TRUE), 'Second key has not been deleted.');
+  }
+
+  /**
+   * Tests Drupal\Core\Cache\CacheBackendInterface::removeBin().
+   */
+  public function testRemoveBin() {
+    $backend_a = $this->getCacheBackend();
+    $backend_b = $this->getCacheBackend('bootstrap');
+
+    // Set both expiring and permanent keys.
+    $backend_a->set('test1', 1, Cache::PERMANENT);
+    $backend_a->set('test2', 3, time() + 1000);
+    $backend_b->set('test3', 4, Cache::PERMANENT);
+
+    $backend_a->removeBin();
+
+    $this->assertFalse($backend_a->get('test1'), 'First key has been deleted.');
+    $this->assertFalse($backend_a->get('test2', TRUE), 'Second key has been deleted.');
+    $this->assertTrue($backend_b->get('test3'), 'Item in other bin is preserved.');
+  }
+
+}

core/modules/system/src/Tests/Cache/MemoryBackendUnitTest.php

@@ -0,0 +1,30 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\system\Tests\Cache\MemoryBackendUnitTest.
+ */
+
+namespace Drupal\system\Tests\Cache;
+
+use Drupal\Core\Cache\MemoryBackend;
+
+/**
+ * Unit test of the memory cache backend using the generic cache unit test base.
+ *
+ * @group Cache
+ */
+class MemoryBackendUnitTest extends GenericCacheBackendUnitTestBase {
+
+  /**
+   * Creates a new instance of MemoryBackend.
+   *
+   * @return
+   *   A new MemoryBackend object.
+   */
+  protected function createCacheBackend($bin) {
+    $backend = new MemoryBackend($bin);
+    \Drupal::service('cache_tags.invalidator')->addInvalidator($backend);
+    return $backend;
+  }
+}

core/modules/system/src/Tests/Cache/PageCacheTagsTestBase.php

@@ -0,0 +1,67 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\system\Tests\Cache\PageCacheTagsTestBase.
+ */
+
+namespace Drupal\system\Tests\Cache;
+
+use Drupal\Core\Url;
+use Drupal\simpletest\WebTestBase;
+use Drupal\Component\Utility\SafeMarkup;
+
+/**
+ * Provides helper methods for page cache tags tests.
+ */
+abstract class PageCacheTagsTestBase extends WebTestBase {
+
+  /**
+   * {@inheritdoc}
+   *
+   * Always enable header dumping in page cache tags tests, this aids debugging.
+   */
+  protected $dumpHeaders = TRUE;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    // Enable page caching.
+    $config = $this->config('system.performance');
+    $config->set('cache.page.max_age', 3600);
+    $config->save();
+  }
+
+  /**
+   * Verify that when loading a given page, it's a page cache hit or miss.
+   *
+   * @param \Drupal\Core\Url $url
+   *   The page for this URL will be loaded.
+   * @param string $hit_or_miss
+   *   'HIT' if a page cache hit is expected, 'MISS' otherwise.
+   *
+   * @param array|FALSE $tags
+   *   When expecting a page cache hit, you may optionally specify an array of
+   *   expected cache tags. While FALSE, the cache tags will not be verified.
+   */
+  protected function verifyPageCache(Url $url, $hit_or_miss, $tags = FALSE) {
+    $this->drupalGet($url);
+    $message = SafeMarkup::format('Page cache @hit_or_miss for %path.', array('@hit_or_miss' => $hit_or_miss, '%path' => $url->toString()));
+    $this->assertEqual($this->drupalGetHeader('X-Drupal-Cache'), $hit_or_miss, $message);
+
+    if ($hit_or_miss === 'HIT' && is_array($tags)) {
+      $absolute_url = $url->setAbsolute()->toString();
+      $cid_parts = array($absolute_url, 'html');
+      $cid = implode(':', $cid_parts);
+      $cache_entry = \Drupal::cache('render')->get($cid);
+      sort($cache_entry->tags);
+      $tags = array_unique($tags);
+      sort($tags);
+      $this->assertIdentical($cache_entry->tags, $tags);
+    }
+  }
+
+}

core/modules/system/src/Tests/Cache/PhpBackendUnitTest.php

@@ -0,0 +1,30 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\system\Tests\Cache\PhpBackendUnitTest.
+ */
+
+namespace Drupal\system\Tests\Cache;
+
+use Drupal\Core\Cache\PhpBackend;
+
+/**
+ * Unit test of the PHP cache backend using the generic cache unit test base.
+ *
+ * @group Cache
+ */
+class PhpBackendUnitTest extends GenericCacheBackendUnitTestBase {
+
+  /**
+   * Creates a new instance of MemoryBackend.
+   *
+   * @return
+   *   A new MemoryBackend object.
+   */
+  protected function createCacheBackend($bin) {
+    $backend = new PhpBackend($bin, \Drupal::service('cache_tags.invalidator.checksum'));
+    return $backend;
+  }
+
+}