     func testConstant_1() {
         let subject = View(frame: CGRect.zero)
         let subject2 = View(frame: CGRect.zero)
-        let constraint = NSLayoutConstraint(item: subject, attribute: NSLayoutAttribute.top, relatedBy: NSLayoutRelation.equal, toItem: subject2, attribute: NSLayoutAttribute.top, multiplier: 0.5, constant: 0.5)
+        let constraint = NSLayoutConstraint(item: subject, attribute: topLayoutAttribute, relatedBy: equalLayoutRelation, toItem: subject2, attribute: topLayoutAttribute, multiplier: 0.5, constant: 0.5)
         Observable.just(1.0).subscribe(constraint.rx.constant).dispose()
 
         XCTAssertTrue(constraint.constant == 1.0)

    func testConstant_0() {
        let subject = View(frame: CGRect.zero)
        let subject2 = View(frame: CGRect.zero)
        let constraint = NSLayoutConstraint(item: subject, attribute: NSLayoutAttribute.top, relatedBy: NSLayoutRelation.equal, toItem: subject2, attribute: NSLayoutAttribute.top, multiplier: 0.5, constant: 0.5)
        Observable.just(0).subscribe(constraint.rx.constant).dispose()

        XCTAssertTrue(constraint.constant == 0.0)

        let subject2 = View(frame: CGRect.zero)
        parent.addSubview(subject)
        parent.addSubview(subject2)
        let constraint = NSLayoutConstraint(item: subject, attribute: topLayoutAttribute, relatedBy: equalLayoutRelation, toItem: subject2, attribute: topLayoutAttribute, multiplier: 0.5, constant: 0.5)
        Observable.just(false).subscribe(constraint.rx.active).dispose()

        XCTAssertTrue(constraint.isActive == false)
