Testing catch block via jest mock - unit-testing

Question

I'm trying to test the 'catch' block of an async redux action via jest, but throwing a catch in the mock causes the test as a whole to fail.
My action is as follows:
export function loginUser(username, password) {
return async dispatch => {
dispatch({type: UPDATE_IN_PROGRESS});
try {
let response = await MyRequest.postAsync(
'/login', {username: username, password: password}
);
dispatch({
type: USER_AUTHENTICATED,
username: response.username,
token: response.token,
role: response.role,
id: response.id
});
} catch (error) {
dispatch({type: USER_SIGNED_OUT});
throw error;
} finally {
dispatch({type: UPDATE_COMPLETE});
}
};
}
The test is trying to mock up 'MyRequest.postAsync' to throw an error and thus trigger the catch block, but the test just bails with a 'Failed' message
it('calls expected actions when failed log in', async() => {
MyRequest.postAsync = jest.fn(() => {
throw 'error';
});
let expectedActions = [
{type: UPDATE_IN_PROGRESS},
{type: USER_SIGNED_OUT},
{type: UPDATE_COMPLETE}
];
await store.dispatch(userActions.loginUser('foo', 'bar'));
expect(store.getActions()).toEqual(expectedActions);
});
Is there a way to trigger the catch block to execute in my test via a jest mock function (or any other way for that matter)? Would be annoying to not be able to test a large chunk of code (as all my requests work in the same way).
Thanks in advance for help with this.

Answer 1

I don't know if it's still relevant, but you can do it in this way:
it('tests error with async/await', async () => {
expect.assertions(1);
try {
await store.dispatch(userActions.loginUser('foo', 'bar'));
} catch (e) {
expect(e).toEqual({
error: 'error',
});
}
});
Here is a documentation about error handling

Answer 2

I had the same issue. For me the below works. Wrapping up the await with a try/catch
it('calls expected actions when failed log in', async() => {
MyRequest.postAsync = jest.fn(() => {
throw 'error';
});
let expectedActions = [
{type: UPDATE_IN_PROGRESS},
{type: USER_SIGNED_OUT},
{type: UPDATE_COMPLETE}
];
try {
await store.dispatch(userActions.loginUser('foo', 'bar'));
} catch(e) {
expect(store.getActions()).toEqual(expectedActions);
}
});

Answer 3

I set the instance variable which we will access in our testing function to undefined so that it will go to catch block.
PS : This might not be possible all the times as we might not be having variables all time
class APIStore {
async fetchProductsAPI() {
try {
const products = networkManager.fetch('products')
this.productsStore.setProducts(prodcuts)
}
catch(e) {
this.apiStatus = API_FAILED
this.apiError = e
}
}
}
Test case
it('Check API Error ', async () => {
const toCheckErrorStore = new APIStore()
// Setting products store to undefined so that execution goes to catch block
toCheckErrorStore.productsStore = undefined
await toCheckErrorStore.fetchProductsAPI()
expect(toCheckErrorStore.apiStatus).toBe(API_FAILED)
expect(toCheckErrorStore.apiError).toEqual(errorObjectIWantToCompareWith)
}