Testing · Junior · Question 34 of 78

What does `jest.spyOn(obj, "method")` / `vi.spyOn` do?

✓Correct answer: Wraps an existing method to record calls; by default it still calls the original
2Deletes the method from the object
3Copies the object for the test

Explanation

Add .mockImplementation(...) to replace the behaviour, and restore the original with mockRestore() after the test.

Further reading

Test yourself

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