Monday, November 1, 2010

Keeping up is fun.

Software development is constantly evolving. Years ago there would be years between product releases, and while there were libraries popping up every so often, there were typically a lot fewer to follow for any given project you might be working on. The pace of change was generally slower.

Today, change is constant and occurring at a significantly faster pace.On top of that, the open-source movement has meant a lot more releases of a lot more useful tools to incorporate within a project. It's easy to get left behind, or running after new versions without a chance to stop and smell the roses.

A perfect example. nUnit is a brilliant unit test framework port for .Net. I've used it for many years, but I've never really given each new version more than a passing glance. Unitl I caught a mention of a new attribute called "[TestCase]". (As opposed to the "[Test]" which denotes a test case.)

Take a case where you want to test a range of outputs such as a minimum, maximum, and assortment of values to ensure a method is working properly. This might be 4 tests or more, consisting of setup, call, and assert. For example I had 3 tests that verified formatting behaviour for a currency converter. Positive value, negative value, and zero. Scenarios like this can now be replaced by something like this:

        [TestCase(1000d, Result = "$1,000.00")]
        [TestCase(-1000d, Result = "-$1,000.00")]
        [TestCase(0d, Result = "$0.00")]
        public string EnsureConverterFormatsCurrencyValues(decimal value)
            IValueConverter testConverter = new DecimalToCurrencyConverter();
            return (string)testConverter.Convert((decimal)value, typeof(decimal), null, CultureInfo.CurrentUICulture);
*Sigh*... Those roses sure smell nice when you finally get a chance. Not only is it one test case (executed and reported 3 times) but it doesn't even need the Assert.Equals line. It would have been nice to have spotted this a year ago when they added it. :)

*Note: The above declaration is actual code, not a typo. The parameters on the attribute are provided as doubles (d) not decimal (m) even though the parameter type is decimal. Decimals cannot be provided via attributes (a limitation in .Net) so TestCase facilitates this translation.

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