Unit tests examples about prism HOT 1 CLOSED

it('should increment', () => {
   const initialState = reducer();

   expect(reducer(initialState, { type: 'Increment' })).toEqual(1);
});

function* apiSaga() {
   yield put({ type: 'SetLoadingSpinner' });
   try {
     yield call(api);
   } finally {
     yield put({ type: 'ResetLoadingSpinner' });
   }
}

// You better do this
function* rootSaga() {
    yield take('CallAPI');

    // You should realize that you can choose between call and fork
    // depending on use case
    yield call(apiSaga);
}

// Instead of this
function* rootSaga(){
    yield take('CallAPI');
    yield* apiSaga();
}

it('should call an API when CallAPI kicks in', function() {
   const it = rootSaga();

   // Saga should wait for CallAPI
   expect(it.next().value).toEqual(take('CallAPI'));

   // And then call the API
   // which is encapsulated in apiSaga, we don't need to test internals
   // because we just rely on the correctness proven by other unit test
   expect(it.next().value).toEqual(apiSaga);
});

it('should show spinner, call api and hide spinner', function() {
  const it = apiSaga();

  // Show the spinner
  expect(it.next().value).toEqual(put({ type: 'SetLoadingSpinner' }));

  // Call API
  expect(it.next().value).toEqual(call(api));

  // Hide the spinner
  expect(it.next().value).toEqual(put({ type: 'ResetLoadingSpinner' }));
});

it('should hide the spinner even when api fails', function() {
  const it = apiSaga();

  // Show the spinner
  expect(it.next().value).toEqual(put({ type: 'SetLoadingSpinner' }));

  // Call API
  expect(it.next().value).toEqual(call(api));

  // Even when API fails, just reset the spinner
  expect(it.throw(new Error('API error'))).toEqual(put({ type: 'ResetLoadingSpinner' }));
});