Unit Testing

For unit testing, Redux Saga Test Plan exports a testSaga function that creates a mock saga for you to assert effects on. testSaga is agnostic about your testing framework, so it simply throws if the sequence of yielded effects don't match your assertion effects.

Pass in your generator function as the first argument. Pass in additional arguments which will be the arguments passed on to the generator function.

// ES2015
import { testSaga } from 'redux-saga-test-plan';

// ES5
var testSaga = require('redux-saga-test-plan').testSaga;

function identity(value) {
  return value;
}

function* otherSaga() {}

function* mainSaga(x, y, z) {
  try {
    const action = yield take('HELLO');
    yield put({ type: 'ADD', payload: x + y });
    yield call(identity, action);
    yield fork(otherSaga, z);
  } catch (e) {
    yield put({ type: 'ERROR', payload: e });
  }
}

const action = { type: 'TEST' };

// saga mock                    x   y  z
const saga = testSaga(mainSaga, 40, 2, 20);

The saga mock has next and throw iterator methods, so you can advance through the saga. Pass in arguments to next to simulate response values from yields. Similarly pass in arguments to throw to specify the thrown error.

Each next and throw call returns an API with effect assertions. All Redux Saga effects are available such as call, put, take, fork, etc. An additional effect called isDone allows you to assert that the generator as reached the end.

function identity(value) {
  return value;
}

function* otherSaga() {}

function* mainSaga(x, y, z) {
  try {
    const action = yield take('HELLO');
    yield put({ type: 'ADD', payload: x + y });
    yield call(identity, action);
    yield fork(otherSaga, z);
  } catch (e) {
    yield put({ type: 'ERROR', payload: e });
  }
}

const action = { type: 'TEST' };

let saga = testSaga(mainSaga, 40, 2, 20);

// try path
saga.next().take('HELLO');
saga.next(action).put({ type: 'ADD', payload: 42 });
saga.next().call(identity, action);
saga.next().fork(otherSaga);
saga.next().isDone();

// Or chain together
saga = testSaga(mainSaga, 40, 2, 20);
saga
  .next()
  .take('HELLO')

  .next(action)
  .put({ type: 'ADD', payload: 42 })

  .next()
  .call(identity, action)

  .next()
  .fork(otherSaga)

  .next()
  .isDone();

// catch path
const error = new Error('My Error');
saga = testSaga(mainSaga, 40, 2, 20);
saga
  .next()

  .throw(error)
  .put({ type: 'ERROR', payload: error })

  .next()
  .isDone();