如果你正在使用MSTest，它最初没有ExpectedException属性，你可以这样做:

try 
{
    SomeExceptionThrowingMethod()
    Assert.Fail("no exception thrown");
}
catch (Exception ex)
{
    Assert.IsTrue(ex is SpecificExceptionType);
}

这适用于Visual Studio Team Test(又名MSTest) 在处理数据库或http事务时。系统应该在某处抛出异常，使用Assert.ThrowExceptionAsync<>()将捕获您的throw事件。(在这些情况下，Assert.ThrowException<>()不会捕获异常)。

   [TestMethod]
   public void Invalid_Input_UserName_Should_Throw_Exception()
   {
       await Assert.ThrowExceptionAsync<ExpectedExceptionType>(()=> new LogonInfo(InvalidInputInUserNameFormat,"P@ssword"));
   }

我最喜欢的实现方法是编写一个名为Throws的方法，并像使用其他Assert方法一样使用它。不幸的是，.NET不允许你编写静态扩展方法，所以你不能像使用Assert类中的构建一样使用这个方法;创建另一个MyAssert或类似的东西。类看起来像这样:

using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace YourProject.Tests
{
    public static class MyAssert
    {
        public static void Throws<T>( Action func ) where T : Exception
        {
            var exceptionThrown = false;
            try
            {
                func.Invoke();
            }
            catch ( T )
            {
                exceptionThrown = true;
            }

            if ( !exceptionThrown )
            {
                throw new AssertFailedException(
                    String.Format("An exception of type {0} was expected, but not thrown", typeof(T))
                    );
            }
        }
    }
}

这意味着你的单元测试看起来是这样的:

[TestMethod()]
public void ExceptionTest()
{
    String testStr = null;
    MyAssert.Throws<NullReferenceException>(() => testStr.ToUpper());
}

它的外观和行为更像单元测试语法的其余部分。

这取决于您使用的测试框架?

例如，在MbUnit中，您可以用一个属性指定预期的异常，以确保您得到的是真正预期的异常。

[ExpectedException(typeof(ArgumentException))]

在VS内置单元测试中，如果你只是想验证抛出了“任何异常”，但你不知道类型，你可以使用catch all:

[TestMethod]
[ExpectedException(typeof(Exception), AllowDerivedTypes = true)]
public void ThrowExceptionTest()
{
    //...
}

Even though this is an old question, I would like to add a new thought to the discussion. I have extended the Arrange, Act, Assert pattern to be Expected, Arrange, Act, Assert. You can make an expected exception pointer, then assert it was assigned to. This feels cleaner than doing your Asserts in a catch block, leaving your Act section mostly just for the one line of code to call the method under test. You also don't have to Assert.Fail(); or return from multiple points in the code. Any other exception thrown will cause the test to fail, because it won't be caught, and if an exception of your expected type is thrown, but the it wasn't the one you were expecting, Asserting against the message or other properties of the exception help make sure your test won't pass inadvertently.

[TestMethod]
public void Bar_InvalidDependency_ThrowsInvalidOperationException()
{
    // Expectations
    InvalidOperationException expectedException = null;
    string expectedExceptionMessage = "Bar did something invalid.";

    // Arrange
    IDependency dependency = DependencyMocks.Create();
    Foo foo = new Foo(dependency);

    // Act
    try
    {
        foo.Bar();
    }
    catch (InvalidOperationException ex)
    {
        expectedException = ex;
    }

    // Assert
    Assert.IsNotNull(expectedException);
    Assert.AreEqual(expectedExceptionMessage, expectedException.Message);
}