Visual Studio "Debug Unit Test" fails to hit breakpoints

When using Visual Studio 2008 and debugging my unit tests... sometimes the debugger works fine. However very often after modifying some code then clicking "Debug Unit Test" Visual Studio will fail to hit the breakpoints in the code. The debugger basically hangs and eventually the tests runs with the new code anyway, but never stops to let me see what is going on.

I'm assuming this has something to do with some type of assembly caching done by the debugger, but not matter what I do (clean project, delete bin folders, restart VS, etc) I can never get the right assembly to load. Has anyone else seen this behavior? Any solutions?

By the way, using Resharper 4.5, and .NET 3.5 on Win XP.

I just had a problem hitting breakpoints in VS2015.

I am always using the solution configuration called Debug but for some reason my solution was set to build the Release version.

Switching from Release to Debug in the dropdown at the top of Visual Studio fixed my problem.

Right click + Run Test(s) will not hit the breakpoint.

Right click + Debug Test(s) will!

Another workaround: Force the debugger to be launched from within your unit test:

System.Diagnostics.Debugger.Launch();