fetch-mock: No fallback response defined for POST

All my GET requests are going through but POST ones fail. This happens when I update fetch-mock from 7.3.0 to 7.3.1 or later.

console.warn Unmatched POST to url

Error fetch-mock: No fallback response defined for POST to url

http.js

export const get = (url) => {
const options = {
method: 'GET',
credentials: 'same-origin'
};
return fetch(url, options).then(handleJsonResponse);
};
export const post = (url, body) => {
const headers = {
'content-type': 'application/json',
'pragma': 'no-cache',
'cache-control': 'no-cache'
};
return fetch(url, {
credentials: 'same-origin',
method: 'POST',
cache: 'no-cache',
body: JSON.stringify(body),
headers
}).then(handleJsonResponse);
};

http.spec.js

const url = '/path/to/url'
describe('get', () => {
it('makes a GET request', async () => {
fetchMock.mock({
name: 'route',
matcher: url,
method: 'GET',
credentials: 'same-origin',
response: {
status: 200,
body: []
}
});
const response = await get(url);
expect(fetchMock.called()).toEqual(true);
expect(fetchMock.calls().length).toEqual(1);
expect(fetchMock.calls('route').length).toEqual(1);
expect(response).toEqual([]);
});
});
describe('post', () => {
const requestBody = {request: 'request'};
it('makes a POST request', async () => {
fetchMock.mock({
name: 'route',
matcher: url,
method: 'POST',
credentials: 'same-origin',
cache: 'no-cache',
body: JSON.stringify(requestBody),
headers: {
'content-type': 'application/json',
'pragma': 'no-cache',
'cache-control': 'no-cache'
},
response: {
status: 200,
body: []
}
});
const response = await post(url, requestBody);
expect(fetchMock.called()).toEqual(true);
expect(fetchMock.calls().length).toEqual(1);
expect(fetchMock.calls('route').length).toEqual(1);
expect(fetchMock.lastOptions().headers).toEqual({
'content-type': 'application/json',
'pragma': 'no-cache',
'cache-control': 'no-cache'
});
expect(response).toEqual([]);
});
});

Any thoughts on what's causing this? Is there a way to get more meaningful logs to help with debugging this?

I would rather not go the alternative path of trying nock or jest-fetch-mock.

Alright, after hours of digging into the library itself I have found out where the issue was.

In my code (and the snippet above) I am stringifying the body JSON.stringify(body). The library's generate-matcher.js is parsing it JSON.parse(body) and then compares the two - the point which was causing the failure. I am now just sending it as the raw object.

In case anyone else ends up here in the future, I had the same error accompanied with fetch-mock unmatched get.

I saw the response to this issue filed to fetch-mock which prompted me to double check my expected values and mocked values.

It turns out my problem was exactly as the error described, where the mock route I was expecting and the actual route that was being called were mismatched because of a typo.