MSDN Magazine - January 2008 - (Page 11)

Advanced Unit Testing, Object Mocking, Profiling Your Apps, and More JAMES AVERY Advanced Unit Testing Unit testing has gradually moved from a fringe technology to standard practice on many Microsoft® .NET Framework projects. Many .NET developers have at least some experience working with nUnit, the predominant unit-testing framework for .NET. While nUnit covers most required scenarios for unit testing .NET applications, you can take unit testing to the next level with MbUnit 2.4. MbUnit is an open-source unit-testing framework started by Jonathan “Peli” de Halleux (who has since gone on to work at Microsoft Research) and is currently led by Andy Stopford along with a team of talented developers. MbUnit starts with the general functionality that most xUnit-testing frameworks include: test fixtures with setup and teardown attributes, the familiar test attribute, a number of assertions, a console test runner, and an easy-to-use windows test runner. But MbUnit differentiates itself from other unit-testing frameworks with some very useful and innovative extras. Row testing is a feature that allows you to pass in parameters to your unit tests. Instead of writing separate tests for each different scenario you want to examine, you can write one test with parameters and then pass in data using convenient attributes. For instance, you might have a method that accepts a book name and ISBN number and then checks if that book is in stock. Instead of writing different tests for books in stock, books out of stock, and books that aren’t in the database, you can write one test method that accepts a book name and ISBN number as parameters. Then, using the Row attribute, you can specify three different sets of values for MbUnit Provides Advanced Unit-Testing Support for .NET Developers each different scenario as well as what the expected result would be. Not only does this reduce the amount of code you have to write for your tests, it also makes those tests more readable and maintainable in the future. A similar feature, pair-wise testing, allows you to use factories to feed data into your unit test. Factories make it easy to test a very large number of data scenarios without a lot of code. Continuing the example from above, you could create a factory that returns hundreds, even thousands, of books and ISBN numbers. MbUnit is even smart enough to eliminate combinations in testing data that would be redundant based on earlier combinations. MbUnit also includes a number of performance-oriented test attributes. The duration attribute can be used to find the amount of time it takes for your test to execute. MbUnit also gives you the ability to write tests that can read and make an assertion based on the value of a performance counter using the PerfCounter attribute. Finally, MbUnit includes another useful feature called the Rollback attribute, which will wrap your test in a transaction and then roll back that transaction when the test is done. This way, you don’t end up with a database full of test data. This feature works in both the .NET Framework 1.1 (using COM+ transactions) and in the .NET Framework 2.0 (using the new built-in transaction support). Price: Free; source code available. www.mbunit.com Better Testing with Mocks The more unit tests you create, the longer it takes to run those unit tests. Ideally, unit tests should take only seconds to run so developers can run them every time they build the application. However, most applications today rely heavily on databases, Web services, and myriad other external dependencies. There is no way a large set of unit tests that use one of these dependencies, can run in seconds. Actually, the only way your unit tests can run that quickly is if you use something to simulate the external dependency. This is where mocks come into the picture. Mocks are objects that pretend to be your external dependency so that your code can run normally using the mock object instead of the external dependency. Not only does this ensure that your tests run quickly, but perhaps more importantly, it allows you to focus on testing the functionality of your code instead january2008 11 http://www.mbunit.com

Table of Contents Feed for the Digital Edition of MSDN Magazine - January 2008

MSDN Magazine - January 2008 Contents Toolbox CLR Inside Out Data Points Advanced Basics Cutting Edge IIS 7.0 - Enhance Your Apps with the Integrated ASP.NET Pipeline World Ready - Around the World with ASP.NET AJAX Applications WCF Syndication - HTTP Programming with WCF and the .NET Framework 3.5 Wicked Code Foundations Extreme ASP.NET {End Bracket}

MSDN Magazine - January 2008

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