单元测试：DateTime.Now [英] Unit Testing: DateTime.Now

问题描述

我有一些单元测试，预计当前时间比DateTime.Now不同，我不想更改计算机的时间，很明显。什么是实现这一目标的最佳策略？

I have some unit tests that expects the 'current time' to be different than DateTime.Now and I don't want to change the computer's time, obviously. What's the best strategy to achieve this?

感谢

推荐答案

在最的策略是的把当前时间的抽象，并注入了抽象进入消费。

的或者的，你也可以定义一个抽象的时间作为周围语境

Alternatively, you can also define a time abstraction as an Ambient Context:

public abstract class TimeProvider
{
    private static TimeProvider current =
        DefaultTimeProvider.Instance;

    public static TimeProvider Current
    {
       get { return TimeProvider.current; }
       set 
       {
           if (value == null)
           {
               throw new ArgumentNullException("value");
           }
           TimeProvider.current = value; 
       }
   }

   public abstract DateTime UtcNow { get; }

   public static void ResetToDefault()
   {    
       TimeProvider.current = DefaultTimeProvider.Instance;
   }            
}

这将使您能够使用它是这样的：

This will enable you to consume it like this:

var now = TimeProvider.Current.UtcNow;

在一个单元测试，你可以用一个测试双人/模仿对象替换 TimeProvider.Current 。使用起订量例如：

In a unit test, you can replace TimeProvider.Current with a Test Double/Mock object. Example using Moq:

var timeMock = new Mock<TimeProvider>();
timeMock.SetupGet(tp => tp.UtcNow).Returns(new DateTime(2010, 3, 11));
TimeProvider.Current = timeMock.Object;

不过，与静态的单元测试，总是通过调用记得拆掉你的灯具 TimeProvider.ResetToDefault（）。

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