Is there a test missing in the grade-school exercise?

[pedrorolo]

When implementing this exercise I assumed a student could only belong in a single grade. This requirement makes the exercise interesting because the most convenient storage data structure is not the one that is meant to serve as output, and I wonder to which degree this wasn't the intended challenge underlying this exercise.

I thus propose adding the following test to the exercise:

  it("A student can't be in two different grades", () => {
    gradeSchool.addStudent('Aimee', 2)
    gradeSchool.addStudent('Aimee', 1)

    const emptyGrade = gradeSchool.studentsInGrade(2)
    const expectedDb = new Map(Object.entries({ 2: ['Aimee'] }))
    expect(emptyGrade).toEqual([])
  })

I would like to make a pull-request with this change, but first I wanted to confirm if this implicit requirement makes sense.

[SleeplessByte]

This exercise was meant to teach/test the students understanding of immutability. The internal structure for storage, and the method of ensuring the return values are copies of the data are open for the student.

What structure was possible before this test and isn't after? I personally don't see the value in complicating the exercise, also because Aimee could be a different person in both grades (ie. names aren't necessarily unique).

[pedrorolo]

What structure was possible before this test and isn't after? I personally don't see the value in complicating the exercise, also because Aimee could be a different person in both grades (ie. names aren't necessarily unique).

I am sorry, but names are necessarily unique, due to how the problem is specified on the README:

Note that all our students only have one name. (It's a small town, what do you want?)

And now, by noticing this requirement in the README, it becomes more and more clear that it makes sense to add the mentioned test case to this exercise. Or otherwise make the README more clear, by stating whether a student can simultaneously belong in different grades or not.

IMHO the exercise is a much more interesting challenge when a student cannot belong to two different grades, because one is forced to output a different data-structure than the one which is a better fit for storage and manipulation
.

[SleeplessByte]

No need to apologise. You're right. In this exercise names are unique.

That said, forcing a certain implementation is not the goal of any V2 exercise in Exercism. Your proposed test case does not force said implementation (it can still be satisfied without using a Map), so I actually don't mind having it.

You may open a PR that adds the test case and changes the example so that it matches the implementation. It would also be great if you could add the test case to the problem-specifications repository, so that other tracks may benefit from this ❤️

[SleeplessByte]

This has been merged!