Jest — mockReset for afterEach affect toHaveBeenCalledTimes

Problem

I used Jest to mock the function for unit test on the nodeJS application. I ran into a situation that the toHaveBeenCalledTimes actual value not correct for the second ‘it’ test case. The called times count was one more than the expected value.

Therefore, I though that it may accumulate the previous toHaveBeenCalledTimes count for the first test case. Then I found out that I didn’t call mockReset for this newly used method.

Solution

I added the function.mockReset() in the afterEach hook and the count was matched after. This way will reset toHaveBeenCalledTimes for the mock function after each test case.

afterEach(() => {
    function.mockReset();
});
expect(function).toHaveBeenCalledTimes(1);