public function testAnd()
 {
     $query = ['$and' => [['$or' => [['price' => ['$eq' => 0.99]], ['price' => ['$eq' => 1.99]]]], ['$or' => [['sale' => ['$eq' => true]], ['qty' => ['$lt' => 20]]]]]];
     $firstOrQuery = $this->filter->newFilter()->addOr($this->filter->newFilter()->field('price')->eq(0.99))->addOr($this->filter->newFilter()->field('price')->eq(1.99));
     $secondOrQuery = $this->filter->newFilter()->addOr($this->filter->newFilter()->field('sale')->eq(true))->addOr($this->filter->newFilter()->field('qty')->lt(20));
     $this->filter->addAnd($firstOrQuery)->addAnd($secondOrQuery);
     $this->assertEquals($query, $this->filter->toArray());
 }