Ordering broken unit tests for focused debugging

Current unit test frameworks present broken unit tests in an arbitrary order, but developers want to focus on the most specific ones first. We have therefore inferred a partial order of unit tests corresponding to a coverage hierarchy of their sets of covered method signatures: When several unit tests in this coverage hierarchy break, we can guide the developer to the test calling the smallest number of methods. Our experiments with four case studies indicate that this partial order is semantically meaningful, since faults that cause a unit test to break generally cause less specific unit tests to break as well.