 
     func test_view1_equal_constant() {
         let constraint = (view1[.Width] == 12345)
-        let firstView = constraint.firstItem as! UIView
         XCTAssertTrue(view1.isEqual(constraint.firstItem))
         XCTAssertEqual(constraint.firstAttribute, NSLayoutAttribute.Width)
         XCTAssertEqual(constraint.relation, NSLayoutRelation.Equal)


    func test_constant_greater_than_or_equal_view1() {
        let constraint = (12345 >= view1[.Width])
        let firstView = constraint.firstItem as! UIView
        XCTAssertTrue(view1.isEqual(constraint.firstItem))
        XCTAssertEqual(constraint.firstAttribute, NSLayoutAttribute.Width)
        XCTAssertEqual(constraint.relation, NSLayoutRelation.LessThanOrEqual)


    func test_constant_equal_view1() {
        let constraint = (12345 == view1[.Width])
        XCTAssertTrue(view1.isEqual(constraint.firstItem))
        XCTAssertEqual(constraint.firstAttribute, NSLayoutAttribute.Width)
        XCTAssertEqual(constraint.relation, NSLayoutRelation.Equal)
