Google\Cloud\Tests\Datastore\Query\QueryTest::testDistinctOn PHP Method

    public function testDistinctOn()
    {
        $self = $this->query->distinctOn('propname');
        $this->assertInstanceOf(Query::class, $self);
        $res = $this->query->queryObject();
        $this->assertEquals($res['distinctOn'], [['name' => 'propname']]);
    }