Doctrine\MongoDB\Aggregation\Stage\Match::getExpression PHP Method

    public function getExpression()
    {
        return ['$match' => $this->query->getQuery()];
    }

 public function testMatchStage()
 {
     $matchStage = new Match($this->getTestAggregationBuilder());
     $matchStage->field('someField')->equals('someValue');
     $this->assertSame(array('$match' => array('someField' => 'someValue')), $matchStage->getExpression());
 }