If there are failed tests, debug them with these steps:

1. Go to definitions of failed tests. Assume that `testMoveAttachedTabBeforeHiddenTab` failed.
2. Set test functions' property `.runnable` to `true`, like: `testMoveAttachedTabBeforeHiddenTab.runnable = true;` then only those tests are ran and others are ignored.
3. Debug them until all tests become green.
4. Revert lines setting `.runnable` and run all tests again.
5. Back to the step 1 if there is any failed test.