Added test for SQLite GUID implementation

tests/Doctrine/Tests/DBAL/Functional/Ticket/DBAL421Test.php

+<?php
+
+namespace Doctrine\Tests\DBAL\Functional\Ticket;
+
+/**
+ * @group DBAL-421
+ */
+class DBAL421Test extends \Doctrine\Tests\DbalFunctionalTestCase
+{
+    protected function setUp()
+    {
+        parent::setUp();
+
+        $platform = $this->_conn->getDatabasePlatform()->getName();
+        if (!in_array($platform, array('mysql', 'sqlite'))) {
+            $this->markTestSkipped('Currently restricted to MySQL and SQLite.');
+        }
+    }
+
+    public function testGuidShouldMatchPattern()
+    {
+        $guid = $this->_conn->query($this->getSelectGuidSql())->fetchColumn();
+        $pattern = '/[0-9A-F]{8}\-[0-9A-F]{4}\-[0-9A-F]{4}\-[8-9A-B][0-9A-F]{3}\-[0-9A-F]{12}/i';
+        $this->assertEquals(1, preg_match($pattern, $guid), "GUID does not match pattern");
+    }
+
+    /**
+     * This test does (of course) not proof that all generated GUIDs are
+     * random, it should however provide some basic confidence.
+     */
+    public function testGuidShouldBeRandom()
+    {
+        $statement = $this->_conn->prepare($this->getSelectGuidSql());
+        $guids = array();
+        for ($i = 0; $i < 99; $i++)
+        {
+            $statement->execute();
+            $guid = $statement->fetchColumn();
+            $this->assertNotContains($guid, $guids, "Duplicate GUID detected");
+            $guids[] = $guid;
+        }
+    }
+
+    private function getSelectGuidSql()
+    {
+        return "SELECT " . $this->_conn->getDatabasePlatform()->getGuidExpression();
+    }
+}
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