public function testKeys()
{
$snippet = $this->snippetFromMethod(DatastoreClient::class, 'keys');
$snippet->addLocal('datastore', $this->client);
$res = $snippet->invoke('keys');
$this->assertTrue(is_array($res->returnVal()));
$this->assertEquals(10, count($res->returnVal()));
$this->assertInstanceOf(Key::class, $res->returnVal()[0]);
$this->assertEquals('Person', $res->returnVal()[0]->keyObject()['path'][0]['kind']);
}