Code coverage with Visual Studio 2012 vs SONAR (dotcover and gallio)

Question

Today I am running into some discrepancies between Visual Studio 2012 and SONAR code coverage analysis.

When I execute Visual Studio 2012 code coverage analysis Test->Analyze Code Coverage->All Test it throws the below values

• Not Covered 37%
• Covered 63%

But when I execute this analysis through SONAR (gallio and dotcover) it throws the below values

• Unit Test Coverage 55%

Very similar result I get from dotcover in visual studio.

• Code coverage 53%

I am not adding any special flags in the sonar-runner properties file . Or setting something in dotcover .

Answer 1

Code coverage is a tool which allows you to find lines of code that your tests cannot execute. It is a fickle thing, and reaching 100% for it generally involves jumping through many hoops for little gain. Additionally, every code coverage tool takes different things into account.

My favorite test runner at the moment is ContinuousTests, which takes the strategy of checking how many times a method is called by tests and by other code, building a graph to determine the risk involved when the code is modified. This is a good metric to look at when testing something.

You can use code coverage as well, as that can help you determine how code branches and whether or not edge cases are tested, always being careful that your tests deal with the contract of a class rather than the internals.

So ultimately, yes, you're seeing different code coverage results from different tools. That's not really something to worry about.