Re 1: Practice exercises on Exercism are supposed to encourage Test-Driven Development. This is a global platform guideline, see building practice exercises:
Exercism favors Practice Exercises being completed via Test Driven Development. To achieve this, there are two options:
The test runner must run the tests in the order defined in the file AND the test suite must bail on the first failure; or
All but the first test should be skipped by default.
The idea is that the student focuses on solving the exercise in small increments, striving to make one test pass at a time, and not the whole test suite at once.