diff --git a/apps/dav/lib/CalDAV/Activity/Provider/Base.php b/apps/dav/lib/CalDAV/Activity/Provider/Base.php
index 43c3403c5b..72fdd681b8 100644
--- a/apps/dav/lib/CalDAV/Activity/Provider/Base.php
+++ b/apps/dav/lib/CalDAV/Activity/Provider/Base.php
@@ -62,7 +62,7 @@ abstract class Base implements IProvider {
 	 * @return array
 	 */
 	protected function generateObjectParameter($eventData) {
-		if (!is_array($eventData)) {
+		if (!is_array($eventData) || !isset($eventData['id']) || !isset($eventData['name'])) {
 			throw new \InvalidArgumentException();
 		};
 
diff --git a/apps/dav/tests/unit/CalDAV/Activity/Provider/BaseTest.php b/apps/dav/tests/unit/CalDAV/Activity/Provider/BaseTest.php
new file mode 100644
index 0000000000..85eb439f10
--- /dev/null
+++ b/apps/dav/tests/unit/CalDAV/Activity/Provider/BaseTest.php
@@ -0,0 +1,189 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * 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
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\DAV\Tests\unit\CalDAV\Activity\Provider;
+
+use OCA\DAV\CalDAV\Activity\Provider\Base;
+use OCP\Activity\IEvent;
+use OCP\Activity\IProvider;
+use OCP\IUser;
+use OCP\IUserManager;
+use Test\TestCase;
+
+class BaseTest extends TestCase {
+
+	/** @var IUserManager|\PHPUnit_Framework_MockObject_MockObject */
+	protected $userManager;
+
+	/** @var IProvider|Base|\PHPUnit_Framework_MockObject_MockObject */
+	protected $provider;
+
+	protected function setUp() {
+		parent::setUp();
+		$this->userManager = $this->createMock(IUserManager::class);
+		$this->provider = $this->getMockBuilder(Base::class)
+			->setConstructorArgs([
+				$this->userManager
+			])
+			->setMethods(['parse'])
+			->getMock();
+	}
+
+	public function dataSetSubjects() {
+		return [
+			['abc', [], 'abc'],
+			['{actor} created {calendar}', ['actor' => ['name' => 'abc'], 'calendar' => ['name' => 'xyz']], 'abc created xyz'],
+		];
+	}
+
+	/**
+	 * @dataProvider dataSetSubjects
+	 * @param string $subject
+	 * @param array $parameters
+	 * @param string $parsedSubject
+	 */
+	public function testSetSubjects($subject, array $parameters, $parsedSubject) {
+		$event = $this->createMock(IEvent::class);
+		$event->expects($this->once())
+			->method('setRichSubject')
+			->with($subject, $parameters)
+			->willReturnSelf();
+		$event->expects($this->once())
+			->method('setParsedSubject')
+			->with($parsedSubject)
+			->willReturnSelf();
+
+		$this->invokePrivate($this->provider, 'setSubjects', [$event, $subject, $parameters]);
+	}
+
+	public function dataGenerateObjectParameter() {
+		return [
+			[23, 'c1'],
+			[42, 'c2'],
+		];
+	}
+
+	/**
+	 * @dataProvider dataGenerateObjectParameter
+	 * @param int $id
+	 * @param string $name
+	 */
+	public function testGenerateObjectParameter($id, $name) {
+		$this->assertEquals([
+			'type' => 'calendar-event',
+			'id' => $id,
+			'name' => $name,
+		], $this->invokePrivate($this->provider, 'generateObjectParameter', [['id' => $id, 'name' => $name]]));
+	}
+
+	public function dataGenerateObjectParameterThrows() {
+		return [
+			['event'],
+			[['name' => 'event']],
+			[['id' => 42]],
+		];
+	}
+
+	/**
+	 * @dataProvider dataGenerateObjectParameterThrows
+	 * @expectedException \InvalidArgumentException
+	 * @param mixed $eventData
+	 */
+	public function testGenerateObjectParameterThrows($eventData) {
+		$this->invokePrivate($this->provider, 'generateObjectParameter', [$eventData]);
+	}
+
+	public function dataGenerateCalendarParameter() {
+		return [
+			[23, 'c1'],
+			[42, 'c2'],
+		];
+	}
+
+	/**
+	 * @dataProvider dataGenerateCalendarParameter
+	 * @param int $id
+	 * @param string $name
+	 */
+	public function testGenerateCalendarParameter($id, $name) {
+		$this->assertEquals([
+			'type' => 'calendar',
+			'id' => $id,
+			'name' => $name,
+		], $this->invokePrivate($this->provider, 'generateCalendarParameter', [$id, $name]));
+	}
+
+	public function dataGenerateGroupParameter() {
+		return [
+			['g1'],
+			['g2'],
+		];
+	}
+
+	/**
+	 * @dataProvider dataGenerateGroupParameter
+	 * @param string $gid
+	 */
+	public function testGenerateGroupParameter($gid) {
+		$this->assertEquals([
+			'type' => 'group',
+			'id' => $gid,
+			'name' => $gid,
+		], $this->invokePrivate($this->provider, 'generateGroupParameter', [$gid]));
+	}
+
+	public function dataGenerateUserParameter() {
+		$u1 = $this->createMock(IUser::class);
+		$u1->expects($this->any())
+			->method('getDisplayName')
+			->willReturn('User 1');
+		return [
+			['u1', 'User 1', $u1],
+			['u2', 'u2', null],
+		];
+	}
+
+	/**
+	 * @dataProvider dataGenerateUserParameter
+	 * @param string $uid
+	 * @param string $displayName
+	 * @param IUser|null $user
+	 */
+	public function testGenerateUserParameter($uid, $displayName, $user) {
+		$this->userManager->expects($this->once())
+			->method('get')
+			->with($uid)
+			->willReturn($user);
+
+		$this->assertEquals([
+			'type' => 'user',
+			'id' => $uid,
+			'name' => $displayName,
+		], $this->invokePrivate($this->provider, 'generateUserParameter', [$uid]));
+
+		// Test caching (only 1 user manager invocation allowed)
+		$this->assertEquals([
+			'type' => 'user',
+			'id' => $uid,
+			'name' => $displayName,
+		], $this->invokePrivate($this->provider, 'generateUserParameter', [$uid]));
+	}
+}