Sokil\Mongo\AggregatePipelinesTest::testPipeline_MatchCallable PHP Method

    public function testPipeline_MatchCallable()
    {
        $pipeline = new Pipeline($this->collection);
        $pipeline->match(function ($expression) {
            /* @var $expression \Sokil\Mongo\Expression */
            $expression->where('a', 1)->whereLess('b', 12);
        });
        $this->assertEquals('[{"$match":{"a":1,"b":{"$lt":12}}}]', (string) $pipeline);
    }