Question

I have prepared some automatic tests with the Visual Studio Team Edition testing framework. I want one of the tests to connect to the database following the normal way it is done in the program:

string r_providerName = ConfigurationManager.ConnectionStrings["main_db"].ProviderName;

But I am receiving an exception in this line. I suppose this is happening because the ConfigurationManager is a singleton. How can you work around the singleton problem with unit tests?

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Thanks for the replies. All of them have been very instructive.

Answer 1

Have a look at the Google Testing blog:

• Using dependency injection to avoid singletons
• Singletons are Pathological Liars
• Root Cause of Singletons
• Where have all the Singletons Gone?
• Clean Code Talks – Global State and Singletons
• Dependency Injection.

And also:

• Once Is Not Enough
• Performant Singletons

Finally, Misko Hevery wrote a guide on his blog: Writing Testable Code.