In MSTest, How can I verify exact error message using [ExpectedException(typeof(ApplicationException))]

Question

Using MSTest how can I verify the exact error message coming from a test method? I know [ExpectedException(typeof(ApplicationException), error msg)] doesn\'t co

Answer 1

The annoyance with annotations and try/catch blocks is that you don't have a clean separation between the ACT and ASSERT phases of the test. A simpler appraoch is to "capture" the exception as part of the ACT phase using a utitlity routine such as:

public static class Catch
{
    public static Exception Exception(Action action)
    {
        Exception exception = null;

        try
        {
            action();
        }
        catch (Exception ex)
        {
            exception = ex;
        }

        return exception;
    }
}

This allows you to do:

// ACT
var actualException = Catch.Exception(() => DoSomething())

// ASSERT
Assert.IsNotNull(actualException, "No exception thrown");
Assert.IsInstanceOfType(actualException, expectedType);
Assert.AreEqual(expectedExceptionMessage, actualException.Message);