title: TDD with large C# solution virtually impossible due to slow compile speed
body: <p>I am working on a large solution with currently 60 assemblies. There are many assemblies that define common parts for the solution, and then a few entry point assemblies to the system.</p>
  
  <p>TDD is virtually impossible at the moment, as a single line change in the lowest domain layer, forces a rebuild of nearly the entire solution, as the test assembly references various layers of the solution.</p>
  
  <p>What is best practice, to bring the build time down from its current 75seconds to a more 
  acceptable 5 seconds or so? This will make TDD feasible again.</p>
  
  <p>When doing unit tests, some classes require mocks defined by interfaces from other assemblies, and as such have to be referenced in the test assembly. So having a single reference to the other assemblies is not always possible, except at the lowest level of the solution.</p>