使用磁带进行redux-saga测试

Question

I am trying to do testing on redux-saga. When I do generator.next(data).value for some unknown reason, the data is not passed onto the saga function as follows:

const gen = onCreateMessage()

const message = "aa"

gen.next(message).value

///SAGA FUNCTION

export function* onCreateMessage(message) {

    yield put(addMessage(message.payload))

Error message. Cannot read payload of undefined.

Answer 1

The problem is that your generator function accepts the message as an argument so you need to pass that when initializing the generator:

const gen = onCreateMessage( /* the message */ )

You'd then be able to get the next value by doing gen.next().value and verifying your assertion.

Here's a JS Bin with an example: http://jsbin.com/catisu/edit?js,console

 const { put, take } = ReduxSaga.effects; const { expect } = chai; const createMessage = message => ({ type: 'CREATE_MESSAGE', payload: message, }); const addMessage = message => ({ type: 'ADD_MESSAGE', payload: message, }); function* onCreateMessage(message) { yield put(addMessage(message.payload)); } // In your test const message = 'some message'; // Message is passed when the generator is initialized const gen = onCreateMessage(createMessage(message)) let next = gen.next(); // Using Chai here but with tape it'd be the same concept try { expect(next.value).to.eql( put(addMessage(message)) ); console.log('It works!'); } catch(e) { console.error('bummer'); } 

 <script src="https://npmcdn.com/redux-saga@0.11.1/dist/redux-saga.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/chai/3.5.0/chai.min.js"></script> 

Also small thing, but it also looks like your generator is expecting an object with a payload key, so a plain string won't work.