Compare test results

[heinezen]

TestCase should implement a compare() method that can be used to compare the results of two checks. Comparing results can be useful for the following scenarios:

1. Reproducing a test run (e.g. for checking if a detected issue has been fixed)
2. Diffing results of two tests of the same type (e.g. for comparing the APIs reaction to slighlty different API requests)

compare() should be implemented as a classmethod that gets passed two report objects. It should then do the following:

• Check for differences in the issue field.
• Diff the value field. Complexity for this may vary depending on the test case, since there can be optional fields and nested values.
• Return a comparison object (as a dict). The object should contain a flag that indicates whether the results are a match/mismatch and the created diff.