Sokil\Mongo\Pipeline\ExpressionTest::testNormalize_ExpressionCallable PHP Method

    public function testNormalize_ExpressionCallable()
    {
        $expression = Expression::normalize(function ($expression) {
            $subExpression = new Expression();
            $subExpression->mod('$field', 2);
            $expression->add(array(1, function ($expression) {
                $expression->multiply('$field', 12);
            }, $subExpression));
        });
        $this->assertEquals(array('$add' => array(1, array('$multiply' => array('$field', 12)), array('$mod' => array('$field', 2)))), $expression);
    }