Testing · Junior · Question 10 of 78

What should a test check - behaviour or implementation details?

✓Correct answer: Behaviour visible to the user or caller, so refactoring doesn't break tests
2Internal state and private methods, to be as precise as possible
3The exact number of re-renders

Explanation

Tests tied to implementation details fail on safe refactors (false negatives) and can pass when the user-visible result is broken (false positives).

Further reading

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