我有一些单元测试,期望“当前时间”与DateTime不同。显然,我不想改变电脑的时间。
实现这一目标的最佳策略是什么?
我有一些单元测试,期望“当前时间”与DateTime不同。显然,我不想改变电脑的时间。
实现这一目标的最佳策略是什么?
当前回答
关于模拟DateTime有一个特别的注意事项。现在使用TypeMock…
DateTime的值。现在必须放置到一个变量中,以便正确地模拟。例如:
这行不通:
if ((DateTime.Now - message.TimeOpened.Value) > new TimeSpan(1, 0, 0))
然而,这样做:
var currentDateTime = DateTime.Now;
if ((currentDateTime - message.TimeOpened.Value) > new TimeSpan(1, 0, 0))
其他回答
模拟对象。
一个模拟DateTime,返回适合您的测试的Now。
以下是我对这个问题的回答。我将“环境上下文”模式与IDisposable结合起来。你可以使用DateTimeProvider。当前在您的正常程序代码和测试中,您使用using语句覆盖范围。
using System;
using System.Collections.Immutable;
namespace ambientcontext {
public abstract class DateTimeProvider : IDisposable
{
private static ImmutableStack<DateTimeProvider> stack = ImmutableStack<DateTimeProvider>.Empty.Push(new DefaultDateTimeProvider());
protected DateTimeProvider()
{
if (this.GetType() != typeof(DefaultDateTimeProvider))
stack = stack.Push(this);
}
public static DateTimeProvider Current => stack.Peek();
public abstract DateTime Today { get; }
public abstract DateTime Now {get; }
public void Dispose()
{
if (this.GetType() != typeof(DefaultDateTimeProvider))
stack = stack.Pop();
}
// Not visible Default Implementation
private class DefaultDateTimeProvider : DateTimeProvider {
public override DateTime Today => DateTime.Today;
public override DateTime Now => DateTime.Now;
}
}
}
下面是如何在单元测试中使用上述DateTimeProvider
using System;
using Xunit;
namespace ambientcontext
{
public class TestDateTimeProvider
{
[Fact]
public void TestDateTime()
{
var actual = DateTimeProvider.Current.Today;
var expected = DateTime.Today;
Assert.Equal<DateTime>(expected, actual);
using (new MyDateTimeProvider(new DateTime(2012,12,21)))
{
Assert.Equal(2012, DateTimeProvider.Current.Today.Year);
using (new MyDateTimeProvider(new DateTime(1984,4,4)))
{
Assert.Equal(1984, DateTimeProvider.Current.Today.Year);
}
Assert.Equal(2012, DateTimeProvider.Current.Today.Year);
}
// Fall-Back to Default DateTimeProvider
Assert.Equal<int>(expected.Year, DateTimeProvider.Current.Today.Year);
}
private class MyDateTimeProvider : DateTimeProvider
{
private readonly DateTime dateTime;
public MyDateTimeProvider(DateTime dateTime):base()
{
this.dateTime = dateTime;
}
public override DateTime Today => this.dateTime.Date;
public override DateTime Now => this.dateTime;
}
}
}
下面的代码为我工作:
bizDeedMock.Verify(p => p.SetDeed(It.Is<DsPostList>(x => x.PostLists[0].registerDate.Year == DateTime.Now.Year)));
bizDeedMock.Verify(p => p.SetDeed(It.Is<DsPostList>(x => x.PostLists[0].registerDate.Month == DateTime.Now.Month)));
bizDeedMock.Verify(p => p.SetDeed(It.Is<DsPostList>(x => x.PostLists[0].registerDate.Day == DateTime.Now.Day)));
最好的策略是将当前时间封装在一个抽象中,并将该抽象注入到使用者中。
或者,你也可以将时间抽象定义为环境上下文:
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;
}
}
这将使你能够像这样消费它:
var now = TimeProvider.Current.UtcNow;
在单元测试中,您可以替换TimeProvider。当前带有Test Double/Mock对象。使用Moq的例子:
var timeMock = new Mock<TimeProvider>();
timeMock.SetupGet(tp => tp.UtcNow).Returns(new DateTime(2010, 3, 11));
TimeProvider.Current = timeMock.Object;
但是,当使用静态状态进行单元测试时,始终记得通过调用TimeProvider.ResetToDefault()来删除fixture。
也许不太专业,但更简单的解决方案可以在消费者方法中创建一个DateTime参数。例如,不使用像SampleMethod这样的make方法,而是使用带参数的make SampleMethod1。SampleMethod1的测试更简单
public void SampleMethod()
{
DateTime anotherDateTime = DateTime.Today.AddDays(-10);
if ((DateTime.Now-anotherDateTime).TotalDays>10)
{
}
}
public void SampleMethod1(DateTime dateTimeNow)
{
DateTime anotherDateTime = DateTime.Today.AddDays(-10);
if ((dateTimeNow - anotherDateTime).TotalDays > 10)
{
}
}