Applying Test Driven Development to a tightly coupled architecture

Posted by Chris D on Stack Overflow See other posts from Stack Overflow or by Chris D
Published on 2010-03-23T16:28:11Z Indexed on 2010/03/23 16:43 UTC
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Hi all,

I've recently been studying TDD, attended a conference and have dabbled in few tests and already I'm 100% sold, I absolutely love it TDD.

As a result I've raised this with my seniors and they are prepared to give it a chance, so they have tasked me with coming up with a way to implement TDD in the development of our enterprise product.

The problem is our system has evolved since the days of VB6 to .NET and implements alot of legacy technology and some far from best practice development techniques i.e. alot of business logic in the ASP.NET code behind and client script. The largest problem however is how our classes are tightly coupled with database access; properties, methods, constructors - usually has some database access in some form or another.

We use an in-house data access code generator tool that creates sqlDataAdapters that gives us all the database access we could ever want, which helps us develop extremely quickly, however, classes in our business layer are very tightly coupled to this data layer - we aren't even close to implementing some form of repository design. This and the issues above have created me all sorts of problems.

I have tried to develop some unit tests for some existing classes I've already written but the tests take ALOT longer to run since db access is required, not to mention since we use the MS Enterprise Caching framework I am forced to fake a httpcontext for my tests to run successfully which isn't practical. Also, I can't see how to use TDD to drive the design of any new classes I write since they have to be soo tightly coupled to the database ... help!

Because of the architecture of the system it appears I can't implement TDD without some real hack which in my eyes just defeats the aim of TDD and the huge benefits that come with.

Does anyone have any suggestions how I could implement TDD with the constraints I'm bound too? or do I need to push the repository design pattern down my seniors throats and tell them we either change our architecture/development methodology or forget about TDD altogether? :)


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