Testing · Middle · Question 16 of 75

Why does `vi.spyOn(module, "fn")` often fail to affect calls inside the same ES module?

✓Correct answer: Internal calls use the local binding, not the exported object property, so the spy is bypassed
2Spies work only on classes
3ES modules can't be imported in tests

Explanation

Mock the module with vi.mock or move the dependency to another module / inject it.

Further reading

Vitest: Mocking ↗

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