Enable different responses for consecutive calls to the same method

[nathanielks]

Use case: SNS.listSubscriptions doesn't guarantee to list all subscriptions if there are less than 100 items in a region (no public documentation on this, this is from a chat with AWS support). It's expected that if there is a NextToken property in the response, that your application will make a subsequent request to the API with that token to get the next page, and so on and so forth.

At the moment, we're only able to mock the first call to a service method. I'd love the ability to mock what the behavior for consecutive calls to the same method!

Similar to https://github.com/dwyl/aws-sdk-mock/issues/58

When I figure it out, I'll report back with any findings.

[nathanielks]

Ideally it'd be something like:

AWS.mock('SNS', 'listSubscriptions', [{
  Subscriptions: subscriptions,
  NextToken: 'boogers'
}, {
  Subscriptions: moarSubscriptions,
}])

To cover the ability to pass a function, perhaps a generator would be a good option 🤔

[benishak]

+1

[nathanielks]

@benishak here's how I went about doing it:

test('message sends when subscription is not returned in first page of listSubscriptions response', () => {
  const subscriptions = [{
    SubscriptionArn: 'a',
    Owner: '1234567890',
    Protocol: 'lambda',
    Endpoint: 'b',
    TopicArn: 'c'
  }, {
    SubscriptionArn: 'd',
    Owner: '1234567890',
    Protocol: 'lambda',
    Endpoint: 'e',
    TopicArn: 'topicarn'
  }]
  let counter = 0
  const func = (params, callback) => {
    let retval
    switch (counter) {
      case 1:
        retval = {
          Subscriptions: [subscriptions[1]]
        }
        break
      default:
        retval = {
          NextToken: 'boogers',
          Subscriptions: [subscriptions[0]]
        }
    }
    counter++
    callback(null, retval)
  }
  AWS.mock('SNS', 'listSubscriptions', func)
  const SNS = new AWS_SDK.SNS({apiVersion: '2010-03-31'})

  const result = funcToBeTested(SNS)
  const expected = true
  expect(result).toEqual(expected)
})

[nathanielks]

I'm also using Jest as the testing framework. I also require the actual SDK:

const AWS = require('aws-sdk-mock')
const AWS_SDK = require('aws-sdk')

(I'm using Lambda and don't want to do any transpiling, so using native node 6.10 features)

[jcollum-cambia]

Sinon stubs have an onCall property, can you use that?

Calling behavior defining methods like returns or throws multiple times overrides the behavior of the stub. As of Sinon version 1.8, you can use the onCall method to make a stub respond differently on consecutive calls.

http://sinonjs.org/releases/v1.17.7/stubs/

[sgurnani99]

Hi, is there an update on this ticket? We face the same issue and need consecutive calls to return different values. @nathanielks thanks for the post, we shamelessly copied your solution :)