ScalaCheck gives you an ability to focus on your code specification by automating its testing on a large number of randomly generated cases. The test coverage significantly increases without you having to do anything manually. Though optional, it is a very useful component and is highly recommended!

You can run your tests directly in your favorite IDE (i.e. Eclipse or IntelliJ) through integration with JUnit 4 or directly with SBT, which could be used as part of your continuous integration.

If you're a fan of mocking components, you can use Mockito with both ScalaTest and Specs2. ScalaTest also integrates well with ScalaMock, JMock, or EasyMock.