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

    public function field($field)
    {
        $this->query->field((string) $field);
        return $this;
    }

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