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);
}

你可以从Nuget下载一个包，使用:PM> Install-Package MSTestExtensions将Assert.Throws()语法以nUnit/xUnit的风格添加到MsTest。

高级指令:从BaseTest下载程序集并继承，您可以使用Assert.Throws()语法。

Throws实现的主要方法如下所示:

public static void Throws<T>(Action task, string expectedMessage, ExceptionMessageCompareOptions options) where T : Exception
{
    try
    {
        task();
    }
    catch (Exception ex)
    {
        AssertExceptionType<T>(ex);
        AssertExceptionMessage(ex, expectedMessage, options);
        return;
    }

    if (typeof(T).Equals(new Exception().GetType()))
    {
        Assert.Fail("Expected exception but no exception was thrown.");
    }
    else
    {
        Assert.Fail(string.Format("Expected exception of type {0} but no exception was thrown.", typeof(T)));
    }
}

披露:我整理了这个包。

更多信息:http://www.bradoncode.com/blog/2012/01/asserting-exceptions-in-mstest-with.html

好吧，我来总结一下大家之前说过的话…不管怎样，这是我根据好的答案构建的代码:)剩下要做的就是复制和使用…

/// <summary>
/// Checks to make sure that the input delegate throws a exception of type TException.
/// </summary>
/// <typeparam name="TException">The type of exception expected.</typeparam>
/// <param name="methodToExecute">The method to execute to generate the exception.</param>
public static void AssertRaises<TException>(Action methodToExecute) where TException : System.Exception
{
    try
    {
        methodToExecute();
    }
    catch (TException) {
        return;
    }  
    catch (System.Exception ex)
    {
        Assert.Fail("Expected exception of type " + typeof(TException) + " but type of " + ex.GetType() + " was thrown instead.");
    }
    Assert.Fail("Expected exception of type " + typeof(TException) + " but no exception was thrown.");  
}

通常你的测试框架会给出答案。但如果它不够灵活，你可以这样做:

try {
    somethingThatShouldThrowAnException();
    Assert.Fail(); // If it gets to this line, no exception was thrown
} catch (GoodException) { }

正如@Jonas指出的，这并不适用于捕捉基本异常:

try {
    somethingThatShouldThrowAnException();
    Assert.Fail(); // raises AssertionException
} catch (Exception) {
    // Catches the assertion exception, and the test passes
}

如果绝对必须捕获Exception，则需要重新抛出Assert.Fail()。但实际上，这是一个你不应该手写的信号;检查测试框架中的选项，或者查看是否可以抛出更有意义的异常进行测试。

catch (AssertionException) { throw; }

您应该能够根据自己的需要调整这种方法——包括指定要捕获的异常类型。如果你只期望某些类型，完成catch块:

} catch (GoodException) {
} catch (Exception) {
    // not the right kind of exception
    Assert.Fail();
}

如果你使用NUNIT，你可以这样做:

Assert.Throws<ExpectedException>(() => methodToTest());

也可以存储抛出的异常以便进一步验证:

ExpectedException ex = Assert.Throws<ExpectedException>(() => methodToTest());
Assert.AreEqual( "Expected message text.", ex.Message );
Assert.AreEqual( 5, ex.SomeNumber);

参见:http://nunit.org/docs/2.5/exceptionAsserts.html

您可以通过简单的一行代码来实现这一点。

如果你的foo.bar()操作是异步的:

await Assert.ThrowsExceptionAsync<Exception>(() => foo.bar());

如果foo.bar()不是异步的

Assert.ThrowsException<Exception>(() => foo.bar());