Testing · Senior · Question 17 of 75

A test passes alone but fails when the whole file runs. What is the likely cause?

✓Correct answer: Shared state leaking between tests: module-level variables, unrestored mocks, stores, timers or DOM left behind
2The test is too short
3The test runner is outdated

Explanation

Run with random order (--sequence.shuffle in Vitest, --randomize in Jest) to surface such dependencies early.

Further reading

Test yourself

Take the Testing · Senior quiz: questions and options are shuffled, and you get a review of your mistakes at the end.