Unit test suites are often used as a quality tool during the development process to keep the codebase stable as it changes and expands. Tools such as NUnit are often used to run and report on the test suites. However, when implementing unit testing in your build process, you have no way of knowing how much of your code the unit tests are actually testing. This is where code coverage comes in. You can run NUnit within NCover and use the code coverage report to determine which code was not tested by that particular test suite.