Troubleshooting AWS mocks in NodeJS

Question

I have the following test:

const AWSMock = require('aws-sdk-mock');
const AWS = require('aws-sdk');
const sinon = require('sinon');

function sendMetric() {
    const cloudwatch = AWS.CloudWatch();
    cloudwatch.putMetricData();
}

describe('Meh', () => {

    it('meh', () => {
        let sendMetricSpy = sinon.spy();
        AWSMock.mock('CloudWatch', 'putMetricData', sendMetricSpy);
        sendMetric();
        expect(sendMetricSpy.calledOnce).toEqual(true);
    });
});

I expect the test to pass, because I have done what the documentation says. This is a distilled example of what I am trying to achieve in my actual code.

The actual output from running the test is:

 FAIL  functions/monitor/__test__/j.test.js
  Meh
    ✕ meh (10ms)

  ● Meh › meh

    expect(received).toEqual(expected) // deep equality

    Expected: true
    Received: false

      14 |         AWSMock.mock('CloudWatch', 'putMetricData', sendMetricSpy);
      15 |         sendMetric();
    > 16 |         expect(sendMetricSpy.calledOnce).toEqual(true);
         |                                          ^
      17 |     });
      18 | });
      19 |

I don't know how troubleshoot this further.

I have also tried setting the aws-sdk object explicity, which had the same result.

What am I doing wrong?

HenryTK · Answer 1 · 2020-06-08T09:08:07.430

Answered my own question: the putMetricData call needs to be passed an object with the correct properties. Working example:

const REALAWS = require('aws-sdk');
const sinon = require('sinon');
const AWS = require('aws-sdk-mock');

const metricParams = {
    MetricData: [
        {
            MetricName: 'ServiceIsHealthy',
            Dimensions: [
                {
                    Name: 'Stage',
                    Value: 'foo',
                },
            ],
            StorageResolution: '60',
            Timestamp: new Date(),
            Unit: 'None',
            Value: '1',
        },
    ],
    Namespace: 'namespace',
};

test('Should return API Keys',  () => {

    const putMetricData = () => {
        const cloudwatch = new REALAWS.CloudWatch();
        return cloudwatch.putMetricData(metricParams)
            .promise();
    };

    const sinon = require('sinon');
    const putMetricDataSpy = sinon.spy();

    AWS.mock('CloudWatch', 'putMetricData', putMetricDataSpy);

    const apiNames = putMetricData();
    sinon.assert.calledOnce(putMetricDataSpy);

});

If you pass the method nothing, or an empty object, it fails.

Troubleshooting AWS mocks in NodeJS

1 Answers1