使用ThreadLocal<T>的线程安全SystemClock非常适合我。

ThreadLocal<T>在. net Framework v4.0及更高版本中可用。

/// <summary>
/// Provides access to system time while allowing it to be set to a fixed <see cref="DateTime"/> value.
/// </summary>
/// <remarks>
/// This class is thread safe.
/// </remarks>
public static class SystemClock
{
    private static readonly ThreadLocal<Func<DateTime>> _getTime =
        new ThreadLocal<Func<DateTime>>(() => () => DateTime.Now);

    /// <inheritdoc cref="DateTime.Today"/>
    public static DateTime Today
    {
        get { return _getTime.Value().Date; }
    }

    /// <inheritdoc cref="DateTime.Now"/>
    public static DateTime Now
    {
        get { return _getTime.Value(); }
    }

    /// <inheritdoc cref="DateTime.UtcNow"/>
    public static DateTime UtcNow
    {
        get { return _getTime.Value().ToUniversalTime(); }
    }

    /// <summary>
    /// Sets a fixed (deterministic) time for the current thread to return by <see cref="SystemClock"/>.
    /// </summary>
    public static void Set(DateTime time)
    {
        if (time.Kind != DateTimeKind.Local)
            time = time.ToLocalTime();

        _getTime.Value = () => time;
    }

    /// <summary>
    /// Resets <see cref="SystemClock"/> to return the current <see cref="DateTime.Now"/>.
    /// </summary>
    public static void Reset()
    {
        _getTime.Value = () => DateTime.Now;
    }
}

使用的例子:

[TestMethod]
public void Today()
{
    SystemClock.Set(new DateTime(2015, 4, 3));

    DateTime expectedDay = new DateTime(2015, 4, 2);
    DateTime yesterday = SystemClock.Today.AddDays(-1D);
    Assert.AreEqual(expectedDay, yesterday);

    SystemClock.Reset();
}

你有一些选择:

使用模拟框架并使用DateTimeService(实现一个小型包装器类并将其注入到生产代码中)。包装器实现将访问DateTime，在测试中您将能够模拟包装器类。 使用Typemock隔离器，它可以伪造日期时间。现在，并且不需要您更改测试中的代码。 使用鼹鼠，它也可以伪造日期时间。现在，并且不需要更改生产代码。

一些例子:

使用Moq的包装器类:

[Test]
public void TestOfDateTime()
{
     var mock = new Mock<IDateTime>();
     mock.Setup(fake => fake.Now)
         .Returns(new DateTime(2000, 1, 1));

     var result = new UnderTest(mock.Object).CalculateSomethingBasedOnDate();
}

public class DateTimeWrapper : IDateTime
{
      public DateTime Now { get { return DateTime.Now; } }
}

直接使用隔离器伪造日期时间:

[Test]
public void TestOfDateTime()
{
     Isolate.WhenCalled(() => DateTime.Now).WillReturn(new DateTime(2000, 1, 1));

     var result = new UnderTest().CalculateSomethingBasedOnDate();
}

免责声明-我在Typemock工作

模拟对象。

一个模拟DateTime，返回适合您的测试的Now。

摩尔数:

[Test]  
public void TestOfDateTime()  
{  
      var firstValue = DateTime.Now;
      MDateTime.NowGet = () => new DateTime(2000,1,1);
      var secondValue = DateTime.Now;
      Assert(firstValue > secondValue); // would be false if 'moleing' failed
}

免责声明-我工作的鼹鼠

这些都是很好的答案，这是我在另一个项目中所做的:

用法:

获取今天的真实日期时间

var today = SystemTime.Now().Date;

而不是使用DateTime。现在，你需要使用SystemTime.Now()…这并不难改变，但这种解决方案可能并不适合所有项目。

时间旅行(让我们去5年后)

SystemTime.SetDateTime(today.AddYears(5));

获得我们虚假的“今天”(从“今天”开始算起5年)

var fakeToday = SystemTime.Now().Date;

重置日期

SystemTime.ResetDateTime();

/// <summary>
/// Used for getting DateTime.Now(), time is changeable for unit testing
/// </summary>
public static class SystemTime
{
    /// <summary> Normally this is a pass-through to DateTime.Now, but it can be overridden with SetDateTime( .. ) for testing or debugging.
    /// </summary>
    public static Func<DateTime> Now = () => DateTime.Now;

    /// <summary> Set time to return when SystemTime.Now() is called.
    /// </summary>
    public static void SetDateTime(DateTime dateTimeNow)
    {
        Now = () =>  dateTimeNow;
    }

    /// <summary> Resets SystemTime.Now() to return DateTime.Now.
    /// </summary>
    public static void ResetDateTime()
    {
        Now = () => DateTime.Now;
    }
}

为系统添加一个假程序集(右键单击System reference=>添加假程序集)。

并在测试方法中写入:

using (ShimsContext.Create())
{
   System.Fakes.ShimDateTime.NowGet = () => new DateTime(2014, 3, 10);
   MethodThatUsesDateTimeNow();
}