GenericCacheBackendUnitTestBase.php

<?php

namespace Drupal\KernelTests\Core\Cache;

use Drupal\Core\Cache\Cache;
use Drupal\Core\Cache\CacheBackendInterface;
use Drupal\KernelTests\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];
    }
    
    /**
     * {@inheritdoc}
     */
    protected function setUp() {
        $this->cachebackends = [];
        $this->defaultValue = $this->randomMachineName(10);
        parent::setUp();
        $this->setUpCacheBackend();
    }
    
    /**
     * {@inheritdoc}
     */
    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();
        $this->assertFalse($backend->get('test1'), "Backend does not contain data for cache id test1.");
        $with_backslash = [
            'foo' => '\\Drupal\\foo\\Bar',
        ];
        $backend->set('test1', $with_backslash);
        $cached = $backend->get('test1');
        $this->assertIsObject($cached);
        $this->assertSame($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->assertGreaterThanOrEqual(REQUEST_TIME, $cached->created);
        $this->assertLessThanOrEqual(round(microtime(TRUE), 3), $cached->created);
        $this->assertEquals(Cache::PERMANENT, $cached->expire, 'Expire time is correct.');
        $this->assertFalse($backend->get('test2'), "Backend does not contain data for cache id test2.");
        $backend->set('test2', [
            'value' => 3,
        ], REQUEST_TIME + 3);
        $cached = $backend->get('test2');
        $this->assertIsObject($cached);
        $this->assertSame([
            'value' => 3,
        ], $cached->data);
        $this->assertTrue($cached->valid, 'Item is marked as valid.');
        $this->assertGreaterThanOrEqual(REQUEST_TIME, $cached->created);
        $this->assertLessThanOrEqual(round(microtime(TRUE), 3), $cached->created);
        $this->assertEquals(REQUEST_TIME + 3, $cached->expire, '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);
        $this->assertIsObject($cached);
        $this->assertFalse($cached->valid, 'Item is marked as valid.');
        $this->assertGreaterThanOrEqual(REQUEST_TIME, $cached->created);
        $this->assertLessThanOrEqual(round(microtime(TRUE), 3), $cached->created);
        $this->assertEquals(REQUEST_TIME - 3, $cached->expire, 'Expire time is correct.');
        $this->assertFalse($backend->get('test4'), "Backend does not contain data for cache id test4.");
        $with_eof = [
            'foo' => "\nEOF\ndata",
        ];
        $backend->set('test4', $with_eof);
        $cached = $backend->get('test4');
        $this->assertIsObject($cached);
        $this->assertSame($with_eof, $cached->data);
        $this->assertTrue($cached->valid, 'Item is marked as valid.');
        $this->assertGreaterThanOrEqual(REQUEST_TIME, $cached->created);
        $this->assertLessThanOrEqual(round(microtime(TRUE), 3), $cached->created);
        $this->assertEquals(Cache::PERMANENT, $cached->expire, 'Expire time is correct.');
        $this->assertFalse($backend->get('test5'), "Backend does not contain data for cache id test5.");
        $with_eof_and_semicolon = [
            'foo' => "\nEOF;\ndata",
        ];
        $backend->set('test5', $with_eof_and_semicolon);
        $cached = $backend->get('test5');
        $this->assertIsObject($cached);
        $this->assertSame($with_eof_and_semicolon, $cached->data);
        $this->assertTrue($cached->valid, 'Item is marked as valid.');
        $this->assertGreaterThanOrEqual(REQUEST_TIME, $cached->created);
        $this->assertLessThanOrEqual(round(microtime(TRUE), 3), $cached->created);
        $this->assertEquals(Cache::PERMANENT, $cached->expire, 'Expire time is correct.');
        $with_variable = [
            'foo' => '$bar',
        ];
        $backend->set('test6', $with_variable);
        $cached = $backend->get('test6');
        $this->assertIsObject($cached);
        $this->assertSame($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');
        $this->assertIsObject($cached);
        $this->assertEquals($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->assertEquals('test', $backend->get($cid)->data);
        // Check that the cache key is case sensitive.
        $backend->set('TEST8', 'value');
        $this->assertEquals('value', $backend->get('TEST8')->data);
        $this->assertFalse($backend->get('test8'));
        // Calling ::set() with invalid cache tags. This should fail an assertion.
        try {
            $backend->set('assertion_test', 'value', Cache::PERMANENT, [
                'node' => [
                    3,
                    5,
                    7,
                ],
            ]);
            $this->fail('::set() was called with invalid cache tags, but runtime assertion did not fail.');
        } catch (\AssertionError $e) {
            // Do nothing; continue testing in extending classes.
        }
    }
    
    /**
     * Tests Drupal\Core\Cache\CacheBackendInterface::delete().
     */
    public function testDelete() {
        $backend = $this->getCacheBackend();
        $this->assertFalse($backend->get('test1'), "Backend does not contain data for cache id test1.");
        $backend->set('test1', 7);
        $this->assertIsObject($backend->get('test1'));
        $this->assertFalse($backend->get('test2'), "Backend does not contain data for cache id test2.");
        $backend->set('test2', 3);
        $this->assertIsObject($backend->get('test2'));
        $backend->delete('test1');
        $this->assertFalse($backend->get('test1'), "Backend does not contain data for cache id test1 after deletion.");
        $this->assertIsObject($backend->get('test2'));
        $backend->delete('test2');
        $this->assertFalse($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);
        $this->assertFalse($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();
        $variables = [
            'test1' => 1,
            'test2' => '0',
            'test3' => '',
            'test4' => 12.64,
            'test5' => FALSE,
            'test6' => [
                1,
                2,
                3,
            ],
        ];
        // Create cache entries.
        foreach ($variables as $cid => $data) {
            $backend->set($cid, $data);
        }
        // Retrieve and test cache objects.
        foreach ($variables as $cid => $value) {
            $object = $backend->get($cid);
            $this->assertIsObject($object, sprintf("Backend returned an object for cache id %s.", $cid));
            $this->assertSame($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 = [
            'test3',
            'test7',
            // Cid does not exist.
'test21',
            'test6',
            // Cid does not exist until added before second getMultiple().
'test19',
            'test2',
        ];
        $cids = $reference;
        $ret = $backend->getMultiple($cids);
        // Test return - ensure it contains existing cache ids.
        $this->assertArrayHasKey('test2', $ret, "Existing cache id test2 is set.");
        $this->assertArrayHasKey('test3', $ret, "Existing cache id test3 is set.");
        $this->assertArrayHasKey('test6', $ret, "Existing cache id test6 is set.");
        $this->assertArrayHasKey('test7', $ret, "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->assertGreaterThanOrEqual(REQUEST_TIME, $ret['test2']->created);
        $this->assertLessThanOrEqual(round(microtime(TRUE), 3), $ret['test2']->created);
        $this->assertEquals(Cache::PERMANENT, $ret['test2']->expire, '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->assertSame(3, $ret['test2']->data, "Existing cache id test2 has the correct value.");
        $this->assertSame(5, $ret['test3']->data, "Existing cache id test3 has the correct value.");
        $this->assertSame(13, $ret['test6']->data, "Existing cache id test6 has the correct value.");
        $this->assertSame(17, $ret['test7']->data, "Existing cache id test7 has the correct value.");
        // Test $cids array - ensure it contains cache id's that do not exist.
        $this->assertContains('test19', $cids, "Nonexistent cache id test19 is in cids array.");
        $this->assertContains('test21', $cids, "Nonexistent cache id test21 is in cids array.");
        // Test $cids array - ensure it does not contain cache id's that exist.
        $this->assertNotContains('test2', $cids, "Existing cache id test2 is not in cids array.");
        $this->assertNotContains('test3', $cids, "Existing cache id test3 is not in cids array.");
        $this->assertNotContains('test6', $cids, "Existing cache id test6 is not in cids array.");
        $this->assertNotContains('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->assertArrayHasKey('test2', $ret, "Existing cache id test2 is set");
        $this->assertArrayHasKey('test7', $ret, "Existing cache id test7 is set");
        $this->assertArrayHasKey('test19', $ret, "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->assertSame(3, $ret['test2']->data, "Existing cache id test2 has the correct value.");
        $this->assertSame(17, $ret['test7']->data, "Existing cache id test7 has the correct value.");
        $this->assertSame(57, $ret['test19']->data, "Added cache id test19 has the correct value.");
        // Test $cids array - ensure it contains cache id's that do not exist.
        $this->assertContains('test3', $cids, "Deleted cache id test3 is in cids array.");
        $this->assertContains('test6', $cids, "Deleted cache id test6 is in cids array.");
        $this->assertContains('test21', $cids, "Nonexistent cache id test21 is in cids array.");
        // Test $cids array - ensure it does not contain cache id's that exist.
        $this->assertNotContains('test2', $cids, "Existing cache id test2 is not in cids array.");
        $this->assertNotContains('test7', $cids, "Existing cache id test7 is not in cids array.");
        $this->assertNotContains('test19', $cids, "Added cache id test19 is not in cids array.");
        // Test with a long $cid and non-numeric array key.
        $cids = [
            'key:key' => $long_cid,
        ];
        $return = $backend->getMultiple($cids);
        $this->assertEquals(300, $return[$long_cid]->data);
        $this->assertEmpty($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 = [
            'cid_1' => [
                'data' => 1,
            ],
            'cid_2' => [
                'data' => 2,
            ],
            'cid_3' => [
                'data' => [
                    1,
                    2,
                ],
            ],
            'cid_4' => [
                'data' => 1,
                'expire' => $future_expiration,
            ],
            'cid_5' => [
                'data' => 1,
                'tags' => [
                    'test:a',
                    'test:b',
                ],
            ],
        ];
        $backend->setMultiple($items);
        $cids = array_keys($items);
        $cached = $backend->getMultiple($cids);
        $this->assertEquals($items['cid_1']['data'], $cached['cid_1']->data, 'Over-written cache item set correctly.');
        $this->assertTrue($cached['cid_1']->valid, 'Item is marked as valid.');
        $this->assertGreaterThanOrEqual(REQUEST_TIME, $cached['cid_1']->created);
        $this->assertLessThanOrEqual(round(microtime(TRUE), 3), $cached['cid_1']->created);
        $this->assertEquals(CacheBackendInterface::CACHE_PERMANENT, $cached['cid_1']->expire, 'Cache expiration defaults to permanent.');
        $this->assertEquals($items['cid_2']['data'], $cached['cid_2']->data, 'New cache item set correctly.');
        $this->assertEquals(CacheBackendInterface::CACHE_PERMANENT, $cached['cid_2']->expire, 'Cache expiration defaults to permanent.');
        $this->assertEquals($items['cid_3']['data'], $cached['cid_3']->data, 'New cache item with serialized data set correctly.');
        $this->assertEquals(CacheBackendInterface::CACHE_PERMANENT, $cached['cid_3']->expire, 'Cache expiration defaults to permanent.');
        $this->assertEquals($items['cid_4']['data'], $cached['cid_4']->data, 'New cache item set correctly.');
        $this->assertEquals($future_expiration, $cached['cid_4']->expire, 'Cache expiration has been correctly set.');
        $this->assertEquals($items['cid_5']['data'], $cached['cid_5']->data, 'New cache item set correctly.');
        // Calling ::setMultiple() with invalid cache tags. This should fail an
        // assertion.
        try {
            $items = [
                'exception_test_1' => [
                    'data' => 1,
                    'tags' => [],
                ],
                'exception_test_2' => [
                    'data' => 2,
                    'tags' => [
                        'valid',
                    ],
                ],
                'exception_test_3' => [
                    'data' => 3,
                    'tags' => [
                        'node' => [
                            3,
                            5,
                            7,
                        ],
                    ],
                ],
            ];
            $backend->setMultiple($items);
            $this->fail('::setMultiple() was called with invalid cache tags, but runtime assertion did not fail.');
        } catch (\AssertionError $e) {
            // Do nothing; continue testing in extending classes.
        }
    }
    
    /**
     * @covers \Drupal\Core\Cache\ApcuBackend::deleteMultiple
     * @covers \Drupal\Core\Cache\BackendChain::deleteMultiple
     * @covers \Drupal\Core\Cache\ChainedFastBackend::deleteMultiple
     * @covers \Drupal\Core\Cache\DatabaseBackend::deleteMultiple
     * @covers \Drupal\Core\Cache\MemoryBackend::deleteMultiple
     * @covers \Drupal\Core\Cache\PhpBackend::deleteMultiple
     * @covers \Drupal\Core\Cache\ApcuBackend::deleteMultiple
     * @covers \Drupal\Core\Cache\BackendChain::deleteMultiple
     * @covers \Drupal\Core\Cache\ChainedFastBackend::deleteMultiple
     * @covers \Drupal\Core\Cache\DatabaseBackend::deleteMultiple
     * @covers \Drupal\Core\Cache\MemoryBackend::deleteMultiple
     * @covers \Drupal\Core\Cache\PhpBackend::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');
        // Nonexistent key should not cause an error.
        $backend->delete('test23');
        $backend->deleteMultiple([
            'test3',
            'test5',
            'test7',
            // Nonexistent key should not cause an error.
'test19',
            // Nonexistent key should not cause an error.
'test21',
        ]);
        // Test if expected keys have been deleted.
        $this->assertFalse($backend->get('test1'), "Cache id test1 deleted.");
        $this->assertFalse($backend->get('test3'), "Cache id test3 deleted.");
        $this->assertFalse($backend->get('test5'), "Cache id test5 deleted.");
        $this->assertFalse($backend->get('test7'), "Cache id test7 deleted.");
        // Test if expected keys exist.
        $this->assertNotFalse($backend->get('test2'), "Cache id test2 exists.");
        $this->assertNotFalse($backend->get('test4'), "Cache id test4 exists.");
        $this->assertNotFalse($backend->get('test6'), "Cache id test6 exists.");
        // Test if that expected keys do not exist.
        $this->assertFalse($backend->get('test19'), "Cache id test19 does not exist.");
        $this->assertFalse($backend->get('test21'), "Cache id test21 does not exist.");
        // Calling deleteMultiple() with an empty array should not cause an error.
        $this->assertNull($backend->deleteMultiple([]));
    }
    
    /**
     * Tests 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.');
        $this->assertNotEmpty($backend_b->get('test3'), 'Item in other bin is preserved.');
    }
    
    /**
     * @covers \Drupal\Core\Cache\ApcuBackend::getMultiple
     * @covers \Drupal\Core\Cache\BackendChain::getMultiple
     * @covers \Drupal\Core\Cache\ChainedFastBackend::getMultiple
     * @covers \Drupal\Core\Cache\DatabaseBackend::getMultiple
     * @covers \Drupal\Core\Cache\MemoryBackend::getMultiple
     * @covers \Drupal\Core\Cache\PhpBackend::getMultiple
     * @covers \Drupal\Core\Cache\ApcuBackend::invalidateMultiple
     * @covers \Drupal\Core\Cache\BackendChain::invalidateMultiple
     * @covers \Drupal\Core\Cache\ChainedFastBackend::invalidateMultiple
     * @covers \Drupal\Core\Cache\DatabaseBackend::invalidateMultiple
     * @covers \Drupal\Core\Cache\MemoryBackend::invalidateMultiple
     * @covers \Drupal\Core\Cache\PhpBackend::invalidateMultiple
     */
    public function testInvalidate() {
        $backend = $this->getCacheBackend();
        $backend->set('test1', 1);
        $backend->set('test2', 2);
        $backend->set('test3', 2);
        $backend->set('test4', 2);
        $reference = [
            'test1',
            'test2',
            'test3',
            'test4',
        ];
        $cids = $reference;
        $ret = $backend->getMultiple($cids);
        $this->assertCount(4, $ret, 'Four items returned.');
        $backend->invalidate('test1');
        $backend->invalidateMultiple([
            'test2',
            'test3',
        ]);
        $cids = $reference;
        $ret = $backend->getMultiple($cids);
        $this->assertCount(1, $ret, 'Only one item element returned.');
        $cids = $reference;
        $ret = $backend->getMultiple($cids, TRUE);
        $this->assertCount(4, $ret, 'Four items returned.');
        // Calling invalidateMultiple() with an empty array should not cause an
        // error.
        $this->assertNull($backend->invalidateMultiple([]));
    }
    
    /**
     * Tests Drupal\Core\Cache\CacheBackendInterface::invalidateTags().
     */
    public 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, [
            'test_tag:2',
        ]);
        $backend->set('test_cid_invalidate2', $this->defaultValue, Cache::PERMANENT, [
            'test_tag:2',
        ]);
        $this->assertSame($this->defaultValue, $backend->get('test_cid_invalidate1')->data);
        $this->assertSame($this->defaultValue, $backend->get('test_cid_invalidate2')->data);
        // Invalidate test_tag of value 1. This should invalidate both entries.
        Cache::invalidateTags([
            'test_tag:2',
        ]);
        $this->assertFalse($backend->get('test_cid_invalidate1') || $backend->get('test_cid_invalidate2'), 'Two cache items invalidated after invalidating a cache tag.');
        // Verify that cache items have not been deleted after invalidation.
        $this->assertSame($this->defaultValue, $backend->get('test_cid_invalidate1', TRUE)->data);
        $this->assertSame($this->defaultValue, $backend->get('test_cid_invalidate2', TRUE)->data);
        // Create two cache entries with the same tag and an array tag value.
        $backend->set('test_cid_invalidate1', $this->defaultValue, Cache::PERMANENT, [
            'test_tag:1',
        ]);
        $backend->set('test_cid_invalidate2', $this->defaultValue, Cache::PERMANENT, [
            'test_tag:1',
        ]);
        $this->assertSame($this->defaultValue, $backend->get('test_cid_invalidate1')->data);
        $this->assertSame($this->defaultValue, $backend->get('test_cid_invalidate2')->data);
        // Invalidate test_tag of value 1. This should invalidate both entries.
        Cache::invalidateTags([
            'test_tag:1',
        ]);
        $this->assertFalse($backend->get('test_cid_invalidate1') || $backend->get('test_cid_invalidate2'), 'Two caches removed after invalidating a cache tag.');
        // Verify that cache items have not been deleted after invalidation.
        $this->assertSame($this->defaultValue, $backend->get('test_cid_invalidate1', TRUE)->data);
        $this->assertSame($this->defaultValue, $backend->get('test_cid_invalidate2', TRUE)->data);
        // Create three cache entries with a mix of tags and tag values.
        $backend->set('test_cid_invalidate1', $this->defaultValue, Cache::PERMANENT, [
            'test_tag:1',
        ]);
        $backend->set('test_cid_invalidate2', $this->defaultValue, Cache::PERMANENT, [
            'test_tag:2',
        ]);
        $backend->set('test_cid_invalidate3', $this->defaultValue, Cache::PERMANENT, [
            'test_tag_foo:3',
        ]);
        $this->assertSame($this->defaultValue, $backend->get('test_cid_invalidate1')->data);
        $this->assertSame($this->defaultValue, $backend->get('test_cid_invalidate2')->data);
        $this->assertSame($this->defaultValue, $backend->get('test_cid_invalidate3')->data);
        Cache::invalidateTags([
            'test_tag_foo:3',
        ]);
        // Verify that cache items not matching the tag were not invalidated.
        $this->assertSame($this->defaultValue, $backend->get('test_cid_invalidate1')->data);
        $this->assertSame($this->defaultValue, $backend->get('test_cid_invalidate2')->data);
        $this->assertFalse($backend->get('test_cid_invalidate3'), '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 = [
            'test_tag:1',
            'test_tag:2',
            'test_tag:3',
        ];
        $bins = [
            'path',
            'bootstrap',
            'page',
        ];
        foreach ($bins as $bin) {
            $this->getCacheBackend($bin)
                ->set('test', $this->defaultValue, Cache::PERMANENT, $tags);
            $this->assertNotEmpty($this->getCacheBackend($bin)
                ->get('test'), 'Cache item was set in bin.');
        }
        Cache::invalidateTags([
            'test_tag:2',
        ]);
        // Test that the cache entry has been invalidated in multiple bins.
        foreach ($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.
        $this->assertNotEmpty($this->getCacheBackend($bin)
            ->get('test_cid_invalidate1'), 'Cache items not matching tag were not invalidated.');
    }
    
    /**
     * Tests 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.');
        $this->assertNotEmpty($backend_b->get('test3'), 'Item in other bin is preserved.');
        $this->assertNotEmpty($backend_a->get('test1', TRUE), 'First key has not been deleted.');
        $this->assertNotEmpty($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.');
        $this->assertNotEmpty($backend_b->get('test3'), 'Item in other bin is preserved.');
    }

}