ExpectedException Attribute Usage

Question

I am trying to work with the ExpectedException attribute in a C# UnitTest, but I am having issues getting it to work with my particular Exception. Here's what I got:

NOTE: I wrapped asterisks around the line that is giving me the trouble.

    [ExpectedException(typeof(Exception))]     public void TestSetCellContentsTwo()     {         // Create a new Spreadsheet instance for this test:         SpreadSheet = new Spreadsheet();          // If name is null then an InvalidNameException should be thrown. Assert that the correct          // exception was thrown.         ReturnVal = SpreadSheet.SetCellContents(null, "String Text");         **Assert.IsTrue(ReturnVal is InvalidNameException);**          // If text is null then an ArgumentNullException should be thrown. Assert that the correct         // exception was thrown.         ReturnVal = SpreadSheet.SetCellContents("A1", (String) null);         Assert.IsTrue(ReturnVal is ArgumentNullException);          // If name is invalid then an InvalidNameException should be thrown. Assert that the correct          // exception was thrown.         {             ReturnVal = SpreadSheet.SetCellContents("25", "String Text");             Assert.IsTrue(ReturnVal is InvalidNameException);              ReturnVal = SpreadSheet.SetCellContents("2x", "String Text");             Assert.IsTrue(ReturnVal is InvalidNameException);              ReturnVal = SpreadSheet.SetCellContents("&", "String Text");             Assert.IsTrue(ReturnVal is InvalidNameException);         }     } 

I have the ExpectedException catching the base type Exception. Shouldn't this take care of it? I have tried using AttributeUsage, but it wasn't helping either. I know I can wrap it in a try/catch block, but I'd like to see if I can figure this style out.

Thanks all!

Answer 1

It will fail unless the type of exception is exactly the type you've specified in the attribute e.g

PASS:-

    [TestMethod()]     [ExpectedException(typeof(System.DivideByZeroException))]     public void DivideTest()     {         int numerator = 4;         int denominator = 0;         int actual = numerator / denominator;     } 

FAIL:-

    [TestMethod()]     [ExpectedException(typeof(System.Exception))]     public void DivideTest()     {         int numerator = 4;         int denominator = 0;         int actual = numerator / denominator;     } 

However this will pass ...

    [TestMethod()]     [ExpectedException(typeof(System.Exception), AllowDerivedTypes=true)]     public void DivideTest()     {         int numerator = 4;         int denominator = 0;         int actual = numerator / denominator;     }