Jest - Expectation using MSW

mock.msw.spec.js

it('should post a body correctly', async () => {
    expect.extend({
        toHaveBeenCalledWithBody(mockFn, expectedBody) {
            const {
                mock: {
                    calls: [call],
                },
            } = mockFn;
            let [{ body }] = call;

            body = JSON.stringify(body);
            expectedBody = JSON.stringify(expectedBody);

            const pass = body === expectedBody;

            // console.log({ mockFn, call, body, expectedBody, pass });

            const messageCreator = (passed) => () =>
                `expected ${body} ${passed ? 'not' : ''} to equal ${expectedBody}`;

            return { message: messageCreator(pass), pass };
        },
    });

    const handlerMock = jest.fn((_, res, ctx) =>
        res(ctx.status(200), ctx.json({ result: 'OK' }))
    );

    server.use(rest.post('/any/url', handlerMock));

    const body = { name: 'Ricardo' };

    const response = await axios.post('/any/url', body);

    expect(handlerMock).toHaveBeenCalledWithBody(body);
    expect(handlerMock.mock.calls[0][0]).toMatchObject({
        body: expect.objectContaining({
            name: expect.any(String),
        }),
    });
    expect(response).toMatchObject({
        status: 200,
        data: { result: 'OK' },
    });
});