DatabaseBackendTest.php

<?php

namespace Drupal\KernelTests\Core\Cache;

use Drupal\Core\Cache\DatabaseBackend;

/**
 * Unit test of the database backend using the generic cache unit test base.
 *
 * @group Cache
 */
class DatabaseBackendTest extends GenericCacheBackendUnitTestBase {
    
    /**
     * The max rows to use for test bins.
     *
     * @var int
     */
    protected static $maxRows = 100;
    
    /**
     * Modules to enable.
     *
     * @var array
     */
    public static $modules = [
        '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'), $bin, static::$maxRows);
    }
    
    /**
     * {@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);
        $this->assertSame($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);
        $this->assertSame($cached_value_short, $backend->get($cid_short)->data, "Backend contains the correct value for short, non-ASCII cache id.");
    }
    
    /**
     * Tests the row count limiting of cache bin database tables.
     */
    public function testGarbageCollection() {
        $backend = $this->getCacheBackend();
        $max_rows = static::$maxRows;
        $this->assertSame(0, (int) $this->getNumRows());
        // Fill to just the limit.
        for ($i = 0; $i < $max_rows; $i++) {
            // Ensure that each cache item created happens in a different millisecond,
            // by waiting 1 ms (1000 microseconds). The garbage collection might
            // otherwise keep less than exactly 100 records (which is acceptable for
            // real-world cases, but not for this test).
            usleep(1000);
            $backend->set("test{$i}", $i);
        }
        $this->assertSame($max_rows, $this->getNumRows());
        // Garbage collection has no effect.
        $backend->garbageCollection();
        $this->assertSame($max_rows, $this->getNumRows());
        // Go one row beyond the limit.
        $backend->set('test' . ($max_rows + 1), $max_rows + 1);
        $this->assertSame($max_rows + 1, $this->getNumRows());
        // Garbage collection removes one row: the oldest.
        $backend->garbageCollection();
        $this->assertSame($max_rows, $this->getNumRows());
        $this->assertFalse($backend->get('test0'));
    }
    
    /**
     * Gets the number of rows in the test cache bin database table.
     *
     * @return int
     *   The number of rows in the test cache bin database table.
     */
    protected function getNumRows() {
        $table = 'cache_' . $this->testBin;
        $connection = $this->container
            ->get('database');
        $query = $connection->select($table);
        $query->addExpression('COUNT(cid)', 'cid');
        return (int) $query->execute()
            ->fetchField();
    }

}