data and constructors required by tests: Should we provide them in stubs?

[petertseng]

See in #464 (comment) how I argued:

• The test is expecting the four constructors
• If we don't provide it, the stub solution doesn't compile with the tests.
• If we don't provide it, the student has to read the test file, find all the possible constructors, and make the data type exactly as we want it anyway.

So, I argued to provide it to the student.

We can see that this is distinct from the case where the test demands an abstract type (such as a Robot) and wishes to perform some operations on it. In this case:

• the test doesn't care about the implementation of the type
• the student can choose the representation
• therefore we make a data Robot = Dummy in the stub file

In this issue I'll discuss a few exercises of the first type:

• allergies: Allergen
• meetup: Weekday and Schedule
• space-age: Planet

So, should we give these three exercises the same treatment, and fully define the above-mentioned data types, with constructors?

(If doing so, we can remove the .meta/DONT-TEST-STUB file for each of these exercises)

[rbasso]

I think that this is the way to go. We have to sacrifice a little flexibility in designing exercises, but we gain a more coherent user-experience and automatic testing of stubs. 👍