Visual Studio does not debug when debugging unit tests?

I had the same problem and solved it this way:

• right click on your test project
• go to properties
• open the "build" tab
• uncheck "Optimize code" checkbox

Visual Studio 2010 test not entering debugger on exception

Make sure you are doing "Test->Debug" or "Debug test"/"Debug selected test". Just running tests with configuration set to Debug will not attach debugger to the running test.

'Hope that helps