AssertEx.cs

public static class AssertEx
{
    public static void Throws<T>(Action action) where T : Exception
    {
      Exception actual = null;

      try
      {
        action();
      }
      catch (T ex)
      {
        actual = ex;
      }

      Assert.IsInstanceOfType(actual, typeof(T));
    }

    public static void Throws<T>(Action action, Action<T> assertion) where T : Exception
    {
      Exception actual = null;

      try
      {
        action();
      }
      catch (T ex)
      {
        actual = ex;
      }

      Assert.IsInstanceOfType(actual, typeof(T));
      assertion((T)actual);
    }

    public static void Throws<T>(Action action, Func<T, bool> assertion) where T : Exception
    {
      Exception actual = null;

      try
      {
        action();
      }
      catch (T ex)
      {
        actual = ex;
      }

      Assert.IsInstanceOfType(actual, typeof(T));
      Assert.IsTrue(assertion((T)actual));
    }

    public static T Exception<T>(Action action) where T : Exception
    {
      T actual = null;

      try
      {
        action();
      }
      catch (T ex)
      {
        actual = ex;
      }

      return actual;
    }
}