Jestでモック関数が正しい引数で呼び出されたことを確認する

code: mock-function-called-test.ts

const mockCallback = jest.fn(x => 42 + x);

forEach(0, 1, mockCallback);

// The mock function is called twice

expect(mockCallback.mock.calls.length).toBe(2);

// The first argument of the first call to the function was 0

expect(mockCallback.mock.calls00).toBe(0);

// The first argument of the second call to the function was 1

expect(mockCallback.mock.calls10).toBe(1);

// The return value of the first call to the function was 42

expect(mockCallback.mock.results0.value).toBe(42);