For .Net developers I can recommend the combination of local dev machine continuous testing using NCrunch, manual runs using the unit test runner in Resharper a

For .Net developers I can recommend the combination of local dev machine continuous testing using NCrunch, manual runs using the unit test runner in Resharper and then the NUnit test runner in TeamCity. TeamCity is a gatekeeper. Builds that fail unit testing don't get automatically deployed. Locally NCrunch keeps you updated on what is broken without you having to think about running your tests, since it runs them in the background for you. Resharper unit test runner helps you run and debug specific tests or groups of tests. I work on a large application with many other developers and this flow works well for us.