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