Test suites are trees of tests. You can start the test run at the top of the test tree, in which case all of the test are run (unless otherwise filtered).

If you wish to run all of the tests in the test suite, answer "No" to this question.

You can also specify that only individual tests or sub-branches of the tree are executed during a test run. The harness walks the tree starting with the sub-branches or tests you specify and executes all the tests that it finds. This feature is useful when you want to run only a portion of the test suite. For example, if you run the test suite and only a few tests fail, you can limit subsequent test runs to only those sections of the test tree that had failed results.

If you wish to run only individual tests or selected sections of the test tree, answer "Yes".