Doctrine\MongoDB\Tests\Aggregation\Stage\GroupTest::testGroupWithOperatorInId PHP Метод

    public function testGroupWithOperatorInId()
    {
        $groupStage = new Group($this->getTestAggregationBuilder());
        $groupStage->field('_id')->year('$dateField')->field('count')->sum(1);
        $this->assertSame(['$group' => ['_id' => ['$year' => '$dateField'], 'count' => ['$sum' => 1]]], $groupStage->getExpression());
    }