 
     func test_view1_equal_view2_multiply_constant_subtract_constant() {
         let constraint = (view1[.Width] == view2[.Width] * 0.5 - 4.0)
-        XCTAssertEqual(constraint.firstItem as! UIView, view1)
-        XCTAssertEqual(constraint.firstAttribute, NSLayoutAttribute.Width)
-        XCTAssertEqual(constraint.relation, NSLayoutRelation.Equal)
-        XCTAssertEqual(constraint.secondItem as! UIView, view2)
+        let firstView = constraint.firstItem as! UIView
+        let secondView = constraint.secondItem as! UIView
+        XCTAssertEqual(firstView, view1)
+        XCTAssertEqual(constraint.firstAttribute, NSLayoutAttribute.Width)
+        XCTAssertEqual(constraint.relation, NSLayoutRelation.Equal)
+        XCTAssertEqual(secondView, view2)
         XCTAssertEqual(constraint.secondAttribute, NSLayoutAttribute.Width)
         XCTAssertEqual(constraint.multiplier, 0.5)
         XCTAssertEqual(constraint.constant, -4.0)


    func test_ratio() {
        let constraint = (8.0 * view1[.Width] == 16.0 * view1[.Height])
        XCTAssertEqual(constraint.firstItem as! UIView, view1)
        XCTAssertEqual(constraint.firstAttribute, NSLayoutAttribute.Width)
        XCTAssertEqual(constraint.relation, NSLayoutRelation.Equal)
        XCTAssertEqual(constraint.secondItem as! UIView, view1)
        XCTAssertEqual(constraint.secondAttribute, NSLayoutAttribute.Height)
        XCTAssertEqual(constraint.multiplier, 16.0 / 8.0)
        XCTAssertEqual(constraint.constant, 0.0)


    func test_view1_equal_constant_multiply_view2_add_constant() {
        let constraint = (view1[.Width] == 0.5 * view2[.Width] + 4.0)
        let firstView = constraint.firstItem as! UIView
        let secondView = constraint.secondItem as! UIView
        XCTAssertEqual(firstView, view1)
        XCTAssertEqual(constraint.firstAttribute, NSLayoutAttribute.Width)
        XCTAssertEqual(constraint.relation, NSLayoutRelation.Equal)
        XCTAssertEqual(secondView, view2)
        XCTAssertEqual(constraint.secondAttribute, NSLayoutAttribute.Width)
        XCTAssertEqual(constraint.multiplier, 0.5)
        XCTAssertEqual(constraint.constant, 4.0)
