add functional driver test case for oci8 driver

tests/Doctrine/Tests/DBAL/Functional/Driver/OCI8/DriverTest.php

+<?php
+
+namespace Doctrine\Tests\DBAL\Functional\Driver\OCI8;
+
+use Doctrine\DBAL\Driver\OCI8\Driver;
+use Doctrine\Tests\DBAL\Functional\Driver\AbstractDriverTest;
+
+class DriverTest extends AbstractDriverTest
+{
+    protected function setUp()
+    {
+        if (! extension_loaded('oci8')) {
+            $this->markTestSkipped('oci8 is not installed.');
+        }
+
+        parent::setUp();
+
+        if (! $this->_conn->getDriver() instanceof Driver) {
+            $this->markTestSkipped('oci8 only test.');
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function testConnectsWithoutDatabaseNameParameter()
+    {
+        $this->markTestSkipped('Oracle does not support connecting without database name.');
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function testReturnsDatabaseNameWithoutDatabaseNameParameter()
+    {
+        $this->markTestSkipped('Oracle does not support connecting without database name.');
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function createDriver()
+    {
+        return new Driver();
+    }
+}