The two last days I presented the organization of our solution, and did some improvements.
Next up in the refactorings is to move the service implementations to the same project as the services themselves. They will always be deployed together, so there is no need to keep them in separate assemblies. Each service implementation project contains only one small class, so this is an easy refactoring.
This shaved off another 9 projects and 5-10 seconds of the build time, and we are down to 65-75 seconds.
Finally, I went for the big refactoring, where I put all the code in the DAL projects into a separate folder (and hence namespace) of the business component project. DAL and BC will always be deployed together, so there is no need to keep them in separate assemblies. We should still be diligent about our dependencies within the assemblies.
We are now down to 24 projects (from 51), and the build time is now 48-55 seconds. This is around half the time it was before, which was 90-100 seconds! All units tests are still passing.
What about running the tests? There is a slight reduction in the time it takes to run all the unit tests. Now it takes from 2:00-2:15, and before I started it took 2:20 – 2:40, so a saving of 20-35 seconds.
Changing one class and a corresponding test class, and then running the tests in that test class takes18-21 seconds, which might be less than the 20-25 seconds it used to take, but is not statistically significant.
All in all my conclusion is that there is a almost linear relationship between build time and the number of projects in a solution. I will take this experience back to project team to see what we will actually implement.