Make redux-saga more easily testable
npm install redux-saga-testable![npm][redux-saga-testable]
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Make [redux-saga] more easily testable.
redux-saga-testable is a unit test library for [redux-saga] that runs your
sagas without the need to iterate on the generators yourself, allowing you
to map some effects to values and providing the built-in assertions you
need.
- [Motivation]
- [Getting started]
- [Contribute]
- [License]
- [Tutorial]
- [API]
It's about [redux-saga] and unit tests.
When you write unit tests of sagas, you have to manually iterate on the
generator and pass your next value for each yielded effect. The number of
iterations you have to next() depends on the number of yield in the saga.
If a yield statement is added, removed or just swapped with another, there is
a good chance that you pass your next value to an unexpected effect. This causes
tests boring to write, not easy to understand and too prone to breaking.
Ideally, you should not have to worry about what the saga does behind. You would
just like to map some effects to some values and assert that some arbitrary
effects happened, in a clear and concise way.
If that speaks to you, go to [Getting started].
Get it with npm:
``sh`
npm i -D redux-saga-testable
or yarn:
`sh`
yarn add -D redux-saga-testable
Considering the following saga:
`ts
function* fetchUserWorker(action: FetchUserAction) {
const { userId } = action.payload;
yield put({ type: 'FETCH_USER_REQUEST' });
let user = yield select(selectors.getCurrentUser);
if (user !== undefined) return;
user = yield call(services.getUserById, userId);
yield put({ type: 'FETCH_USER_SUCCESS', payload: user });
}
`
This saga fetches a user and dispatches FETCH_USER_SUCCESS. Note that if theservices.getUserById()
user already exists, it does nothing instead of calling.
You would like to assert that this saga dispatches the action
FETCH_USER_SUCCESS when the call to services.getUserById() returns a user:
`ts
import { createRunner } from 'redux-saga-testable';
test('fetchUserWorker() should dispatch FETCH_USER_SUCCESS', () => {
const userId = 123;
const user = { user: 'name' };
createRunner(fetchUserWorker, { type: 'FETCH_USER', payload: { userId } })
.map(call(services.getUserById, userId), user)
.should.put({ type: 'FETCH_USER_SUCCESS', payload: user });
});
`
Let's see what happens step by step:
- `code`
import { createRunner } from 'redux-saga-testable';
Imports the saga runner creator function.
- `code`
createRunner(fetchUserWorker, { type: 'FETCH_USER', payload: { userId } })
Creates a saga runner instance from the saga fetchUserWorker and its action.
- `code`
.map(call(services.getUserById, userId), user)
Maps the effect call(services.getUserById, id) to the value user.
- `code`
.should.put({ type: 'FETCH_USER_SUCCESS', payload: user });
Asserts that the saga yields the effect
put({ type: 'FETCH_USER_SUCCESS', payload: user }).
The test will pass if the runner can make the given assertions. Otherwise an
error will be thrown and the test will fail.
**See the [Tutorial] for more advanced examples or see the [API]
documentation.**
Pull requests are welcome.
To make one, fork this repository, clone it to your local and run npm install`.
Do your changes. Once you are done, commit and push to your forked repository
and make your pull request.
See current [issues] but feel free to bring what you need.
MIT
[motivation]: #motivation
[getting started]: #getting-started
[contribute]: #contribute
[license]: #license
[api]: docs/api.md
[tutorial]: docs/tutorial.md
[node.js]: https://nodejs.org/
[redux]: https://github.com/reduxjs/redux
[redux-saga]: https://github.com/redux-saga/redux-saga
[redux-saga-testable]: https://www.npmjs.com/package/redux-saga-testable
[issues]: https://github.com/jeromeludmann/redux-saga-testable/issues