Managing Large Numbers of Tests
The Test List Editor and the Test View window display the tests in your solution. Although the Test View window displays a flat list, you can use the Test List Editor to organize tests into a hierarchical structure. This structure consists of test lists. Test lists function both as nodes and as containers; they can contain tests and other test lists.
When your project uses dozens or hundreds of tests, it helps to have the capability of visualizing them in groups, or lists. But this is not the only reason to organize them into lists. You can also run the tests in a list by first selecting the list in the Visual Studio IDE, or you can run the tests in a list using the command-line test utility.
If you have hundreds of unit test methods in a single test class, you might experience a performance issue when you add a new test method to this test class. This issue occurs when the test method is automatically added into the Test View window or the Test List Editor. For more information, see "Performance Issues When Adding Test Methods" in Troubleshooting in Test Edition.