Should I mix my UnitTests and my Integration tests in the same project?

Question

I am using NUnit to test my C# code and have so far been keeping unit tests (fast running ones) and integration tests (longer running) separate, and in separate project files. I use NUnit for doing both the unit tests and the integration tests. I just noticed the category attribute that NUnit provides, so that tests can be categorized. This begs the question, should I mix them together and simply use the category attribute to distinguish between them?

Answer 1

if it is not too difficult to separate them, do so now

unit tests should be run early and often (e.g. every time you change something, before check-in, after check-in), and should complete in a short time-span.

integration tests should be run periodically (daily, for example) but may take significant time and resources to complete

therefore it is best to keep them separate