Mocking a HttpClient with Jest - reactjs

Question

I'm having trouble with my React Native + Jest + Typescript setup.
I'm trying to test a thunk/network operation. I've created a networkClient function:
export const networkClient = async (
apiPath: string,
method = RequestType.GET,
body = {},
authenticate = true,
appState: IAppState,
dispatch: Dispatch<any>
) => {
... validate/renew token, validate request and stuff...
const queryParams = {
method,
headers: authenticate
? helpers.getHeadersWithAuth(tokenToUse)
: helpers.getBaseHeaders(),
body: method === RequestType.POST ? body : undefined,
};
const fullUri = baseURL + apiPath;
const result = await fetch(fullUri, queryParams);
if (result.ok) {
const json = await result.json();
console.log(`Result ${result.status} for request to ${fullUri}`);
return json;
} else {
... handle error codes
}
} catch (error) {
handleNetworkError(error, apiPath);
}
};
Now, when writing my tests for the operations which uses the networkClient above to request server data like so:
const uri = `/subscriptions/media` + tokenParam;
const json = await networkClient(
uri,
RequestType.GET,
undefined,
true,
getState(),
dispatch
);
I'd like to mock the implementation to return a mock response pr. test.
As pr the docs, I thought this could be done like so:
import { RequestType, networkClient} from './path/to/NetworkClient';
and in the test:
networkClient = jest.fn(
(
apiPath: string,
method = RequestType.GET,
body = {},
authenticate = true,
appState: IAppState,
dispatch: Dispatch<any>
) => {
return 'my test json';
}
);
const store = mockStore(initialState);
return store
.dispatch(operations.default.getMoreFeedData(false))
.then(() => {
expect(store.getActions()).toEqual(expectedActions);
expect(store.getState().feedData).toEqual(testFeed);
// fetchMock.restore();
});
but networkClient is not defined, and ts tells me
[ts] Cannot assign to 'networkClient' because it is not a variable.
What did I get wrong? I must have missed something about how Jest mocks modules and how to provide a mock implementation somewhere, but I can't find it on neither the docs, nor on Google/SO.
Any help is much appreciated

Answer 1

So I found the solution
The import should not be
import { RequestType, networkClient} from './path/to/NetworkClient';
but instead the module should be required like so:
const network = require('./../../../../networking/NetworkClient');
After that, i could successfully mock the implementation and complete the test:
const testFeed = { items: feed, token: 'nextpage' };
network.networkClient = jest.fn(() => {
return testFeed;
});
I hope it helps someone