I have an interview question: step 1: the candidate is shown the specification for a method and the results of running the test suite on an obfuscated version

I have an interview question: step 1: the candidate is shown the specification for a method and the results of running the test suite on an obfuscated version of the method. All tests pass. The test suite is minimal, and test coverage is abysmal. step 2: the candidate is asked to come up with more test cases, based on the specification. The code is run against the updated test suite - most new tests will fail because the method's implementation has several known bugs. step 3: The un-obfuscated source is provided and the candidate is asked to correct any bugs they discover. step 4: the changed source is run against a full test suite. I like this because the candidate's ability to think of test cases, debug, and fix existing code are all tested for.