Sunday, September 21, 2008

Getting Categories for MSTest (just like NUnit)

[This was originally posted at]

Short answer: check out:


Long answer: I previously discussed Automating Code Coverage from the Command Line. Another way to buff up your unit tests is to add categories to them. For example, suppose you had several long-wrong tests (perhaps unit testing database procedures), and you wanted the ability to run them separately, using categories, from the command line.

The free, 6-year old, open-source NUnit has category attributes, for which you can filter tests easily by. For a variety of reasons, MSTest - the core testing component of Microsoft's flagship development product, after 2 releases (2005 and 2008) still does not have these. I've had the chance to ask to ask people at MSDN events about these, and I've heard a lot of "reasons":


Proposal for why MSTest does not need categories:Problem with that:
Just put all those tests in a separate DLL
  • This does not handle putting a single test into two categories. Also, it's not feasible, often the tests we want to categorize cannot be so easily isolated.
Just add the description tag to them and then sort by description in the VS GUI
  • You still cannot filter desc from the command line - it requires running in a GUI
  • This fails because it does an exact string comparison instead of a substring search. If you have Description("cat1, cat2"), and Description("cat1") - you cannot just filter by "cat1" and get both tests, it would exclude the first because "cat1" does not match "cat1, cat2".
  • Conceptually, you shouldn't need to put "codes" in a "description" field. Descriptions imply verbose alpha-numeric text, not a lookup code that you can filter by.
Just filter by any of MSTest's advanced filter GUI features - like class or namespace.
  • This requires opening the GUI, but we need to run from the command line.
  • Sometimes the tests we need to filter by span across the standard MSTest groups.
Just use MSTest test lists
  • This is only available for more advanced version of VS.
  • This is hard to maintain. It requires you continually update a global test file (which always becomes a maintenance problem), as opposed to applying the attributes to each test individually.
Well, you shouldn't really need categories, just run all your unit tests every time.
  • Of course your automated builds should eventually run all unit tests, but it's a big time-saver for a developer to occasionally just run a small subset of those.


So, if you want to easily get the equivalent of NUnit categories for your MSTest suite, check out

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