旋轉點測試失敗。爲什麼？

Question

這是我的失敗的Point.cs文件。

// Rotates the point counter-clockwise by deg degrees. For example, applying 
// a 90 degree rotation to (1, 0) should give (0, 1). 
public void rotate(double deg) 
{ 
    double rotCos = Math.Cos(deg * Math.PI/180); 
    double rotSin = Math.Sin(deg * Math.PI/180); 
    double oldX = x; 
    double oldY = y; 
    x = oldX * rotCos - oldY * rotSin; 
    y = oldX * rotSin + oldY * rotCos; 
    Point point = new Point(x, y); 
} 

我運行這個測試並得到結果：

「消息：Assert.AreEqual失敗預期：< 2>：< 2>實際。」

[TestMethod] 
public void Rotate_Test() 
{ 
    double rotate = -90; 
    double i = 4; 
    double o = 2; 
    Point point = new Point(i, o); 
    double expectedX = 2; 
    double expectedY = 4; 

    point.rotate(rotate); 

    Assert.AreEqual(expectedX, point.getX()); 
    Assert.AreEqual(expectedY, point.getY()); 
} 

Answer 1

雙打都沒有確切的數字。他們不應該比較平等沒有指定他們之間的可接受的差異。

https://msdn.microsoft.com/en-us/library/ms243458.aspx

https://msdn.microsoft.com/en-us/library/ya2zha7s(v=vs.110).aspx

嘗試

Assert.AreEqual(expectedX, point.getX(), 0.001);