Specify interface that must be implemented

[pdawyndt]

The test specification might specify the interface that must be implemented. This could be used to

• perform static analysis to see which parts of the interface have been properly implemented; generate feedback if this is not the case; skip dynamic tests depending on portions of the interface that are not (properly) implemented
• generate skeleton code for students in a given programming language
• assign weights to parts of the interface for use in automated grading