Add mapper unit tests

tests/lib/Files/ObjectStore/MapperTest.php

+<?php
+/**
+ * @author Roeland Jago Douma <rullzer@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+namespace Test\Files\ObjectStore;
+
+
+use OC\Files\ObjectStore\Mapper;
+
+class MapperTest extends \Test\TestCase {
+
+	public function dataGetBucket() {
+		return [
+			['user', substr(md5('user'), 0, 3)],
+			['USER', substr(md5('USER'), 0, 3)],
+			['bc0e8b52-a66c-1035-90c6-d9663bda9e3f', substr(md5('bc0e8b52-a66c-1035-90c6-d9663bda9e3f'), 0, 3)],
+		];
+	}
+
+	/**
+	 * @dataProvider dataGetBucket
+	 * @param string $username
+	 * @param string $expectedBucket
+	 */
+	public function testGetBucket($username, $expectedBucket) {
+		$user = $this->getMock('OCP\IUser');
+		$user->method('getUID')
+			->willReturn($username);
+
+		$mapper = new Mapper($user);
+
+		$this->assertSame($expectedBucket, $mapper->getBucket());
+	}
+}
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