Functions · interview question

If you wrote a test around return values, what should the test prove first?

Multiple choiceMediumchapter-2-curatedpremiumfunctionsreturn-values

python

def discount_rate(is_vip: bool, subtotal: float) -> float:
    if is_vip and subtotal >= 100:
        return 0.15
    return 0.0

Keep return values implicit so the script stays short and hope the next engineer infers the rule.Solve the symptom with comments only and avoid changing the code shape around return values.Delay clarity until production traffic reveals the edge case and then patch it under pressure.That the rule behaves correctly at the boundary cases the lesson is trying to make explicit.

Answer and explanation

Correct answer

D. That the rule behaves correctly at the boundary cases the lesson is trying to make explicit.

Why

Good tests make the design safer to change because they lock in the meaningful behavior rather than surface-level implementation details.

Test yourself on Functions

A free test with instant, explained results. No account needed.

Start free test

All Functions questions →

If you wrote a test around return values, what should the test prove first?

Correct answer

Why

More Functions questions