Contract Testing with Pact.js + GraphQL

Contract Tests vs Integration Tests

  • Trustworthy like the API tests, even though the contract test is mocking the provider/consumer, you know it is mocking based on the contract that was generated.
  • Reliable because you don’t depend on your internet connection to get the same consistency on the results (When your API does’t have third parties integration or you are testing locally).
  • Fast because you don’t need internet connection, everything is mocked using the contract that was generated.
  • Cheap because you don’t spend huge amount of time to create a pact test or to run it, even less to maintain.
Contract Tests API Tests
Trustworthy Trustworthy
Reliable Not realiable
Fast Slow
Cheap Expensive

Remember contract tests are NOT about testing the performance of your microservice. So, if you have API Test that are taking ages to (execute/perform), failing due server no replying fast enough or timeouts, this means you have a performance problem, or it is just your internet connection. In either case you need to separate the problem and create targeted tests that are going to verify the performance of your server and not the expected response body/code.

How it works

You can use a framework like Pact which will generate the contract details and fields from the consumer. You need to  specify the data you are going to send and in the verification part you will use the same function the app would use to do the requests to the API.

Contract test is part of an integration test stage where you don’t really need to hit the API, so it is faster and reliable, completely independent of your internet connection. It is trustworthy since you are generating the contract based on the same function and the same way you would do when using the consumer to hit the provider. Pact is responsible to generate this contract for you, so you just need to worry about passing the data and add the assertions, like response code, headers, etc. If It seems pretty straight forward to know who is the consumer, who is the provider and the contract that you are going to generate, but imagine a more complex real life scenario where you have a structure like:

In this case you have multiple microservices communicating with each other and sometimes this service is the provider and sometimes the same service is the consumer. So, to keep the house organised when maintaining these services you need to create a pact between each one of them.


The fun part

So let’s get hands-on now and see how we can actually create these contracts.

Create a helper for the consumer to setup and finalise the provider (this will be the pact mock where the consumer is going to point when creating the pact.

import { Pact } from '@pact-foundation/pact'
import path from 'path'


export const provider = new Pact({
   port: 20002,
   log: path.resolve(process.cwd(), 'logs', 'mockserver-integration.log'),
   dir: path.resolve(process.cwd(), 'pacts'),
   pactfileWriteMode: 'overwrite',
   consumer: 'GraphQLConsumer',
   provider: 'GraphQLProvider'

beforeAll(() => provider.setup())
afterAll(() => provider.finalize())

// verify with Pact, and reset expectations
afterEach(() => provider.verify())


Then create a consumer file where you add what is the data you want to check and the response you are expecting from the graphQL API.

import { Matchers, GraphQLInteraction } from '@pact-foundation/pact'
import { addTypenameToDocument } from 'apollo-utilities'
import gql from 'graphql-tag'
import graphql from 'graphQLAPI'

const { like } = Matchers

const product = {
  id: like('456789').contents,
  disabled: false,
  type: like('shampoo').contents,

describe('GraphQL', () => {
  describe('query product list', () => {
    beforeEach(() => {
      const graphqlQuery = new GraphQLInteraction()
        .uponReceiving('a list of products')
          path: '/graphql',
          method: 'POST'
          status: 200,
          headers: {
            'Content-Type': 'application/json; charset=utf-8'
          body: {
            data: {
              productsList: {
                items: [
                nextToken: null
      return provider.addInteraction(graphqlQuery)

    it('returns the correct response', async () => {
      expect(await graphql.productsList()).toEqual([product])

When you run the script above, pact is going to create a .json file in your pacts folder and this will be used to test the provider side. So, this is going to be the source of truth for your tests.

This is the basic template if you are using jest, just set the timeout and then you need to use the same functions that you are going to use for the consumer to communicate with the provider. You just need to decide how you are going to inject the data in your local database, you can pre-generate all the data on the beforeAll or a pre-test and then add a post-test or a function in your afterAll to clean the database once the tests are done.

The provider.js file should be something similar to this one:

import { Verifier } from '@pact-foundation/pact'
import path from 'path
import server from 'server'


beforeAll(async () => {

afterAll(async () => {

describe('Contract Tests', () => {
       it('validates the pact is correct', () => {
         const config = {
                  pactUrls: [path.resolve(process.cwd(), 'pacts/graphqlconsumer-graphqlprovider.json')],
                  pactBrokerPassword: "Password",
                  pactBrokerUrl: "",
                  pactBrokerUsername: "Username",
         return new Verifier(config).verifyProvider()

In the end you just need to verify that the contract is still valid after your changes on provider or consumer, for this reason you don’t need to add edge scenarios, just exactly what the provider is expecting as data.



Swift and XCUI tests for beginners

I went to a workshop last year #TechKnowDay and I saved this one about Swift for beginners in my draft. I didn’t have a chance to participate, but I followed the instructions on the slide of the project:

I took the chance to do some automation on this project and created the scenarios (without BDD) here:

It is really basic and simple, but it is a start point for everybody who wants to learn how to create the tests.

You can also record the actions, just open your project on Xcode:

  • Create a New Target


  • Type a name for your UITest target


  • Select the UI Testing template


  • Then you just need to click inside of the test function and the record button (red circle) will show up on the bottom of the screen


Thank you Ana for this great workshop !

Deep learning with python

Hello guys, last year I joined to a day of workshops from #TechkNowDay here in London. This workshop is about deep learning with python and I am able to share the power point explaining the exercise with you.

You can download the Power Point presentation here and the list of files for this exercise on this link.

Nice coding everyone !

Thank you so much for the workshop and all the explanation Bianca Furtuna !

Injecting cookies in your testcafe automation

Hello guys,

Today I am going to post an alternative to authenticate without going throught the login page. I have done this before generating a token for Keycloak to authenticate, but in my last project I generated the cookies and added them as a header with testcafe intercepting the HTTP requests to the website.

This is useful for when you don’t need to test the login process or you have a separated feature to test the login page. Then you will be able to save time when running the automation and avoiding to have to sign in every time you launch the scenario.

I had to take this approach for another reason as well, which was this bug here that happened because TestCafe uses a URL-rewritten proxy internally and this proxy is forced to handle cookies manually because the URL of the tested website is changed during test execution.

You will need to add this in a Before hook and generate the cookies before running the scenarios.

So first, install keygrip and cookies in your package:

npm run keygrip base-64

Second you will need to create the cookie based on your authentication process. For example if your cookie is generated with a json like this. You will also need to set the cookie like this and then you can add it in your utils/helper/support class:

import { RequestHook } from 'testcafe';
import Keygrip from 'keygrip';
import Base64 from 'base-64';

class addCookie extends RequestHook {

    constructor (requestFilterRules) {

    async onRequest (event) {
       const cookieName = "name-of-your-cookie-here"; //Change the value with the name of your authentication cookie 
       const cookieSigName = "name-of-your-cookie-here.sig"; //Same as above, but this is the signature cookie 

       let cookieValue = { "name":"username", "email":"" }; //Here you have the value that is inside the cookie 
       cookieValue = Base64.encode(JSON.stringify(cookieValue)); //Encode to Base64 the string if you need it 

       const keys = new Keygrip(["SECRET_KEY"]); //Here you will add your secret
       const hash = keys.sign(`${cookieName}=${cookieValue}`); //This is where you are going to sign the cookie with your secret key

       const myDate = new Date();
       event.requestOptions.headers[cookieName]= `${cookieValue};expires=${myDate};domain=${domain};path=/`;
       event.requestOptions.headers[cookieSigName]= `${hash};expires=${myDate};domain=${domain};path=/`; 

    async onResponse (event) {
       // Anything you need to add when you have the response 



You will need to import the page class and then in the feature level:

import addCookie from 'add-cookie.js';

const setCookies = new addCookie(/https?:\/\/;

fixture`Your Feature`


This is just an idea of how to skip the login screen page when doing automation and saving you sometime, but there are some other suggestions as well, like generating the token and add them to the header.



Chaos Engineering: Why Breaking Things Should be Practiced

Hello guys,

Last week I went to the WebSummit 2018 Conference in Lisbon and I managed to join some of the AWS talks. The talk that I am posting today is about chaos engineering, which specifically address the uncertainty of distributed systems at scale. The aim of this practice is to uncover the system weakness and build confidence in the system’s capability. 

The harder it is to disrupt the steady state, the more confidence we have in the behavior of the system.  If a weakness is uncovered, we now have a target for improvement before that behavior manifests in the system at large.

Today I am going to post the video on the exact moment that this talk starts.

This talk is presented by AWS Technical Evangelist Adrian Hornsby.

You can find tools to help you with the tests in this repo:



Amazing repo with content/links about the topic:

How do you help developers to test ?

Hello guys,

I have joined to some webinars from Test Masters Online, not sure if you heard about them, but this one really called my attention. The title looks a bit extreme, but you will see that is more about how testers and developers can work together to improve the quality of the team. The ideal is to have specialised QAs that can teach developers about automation, performance, security tests and so on. It is more about giving awareness about tests when developing.

The challenge nowadays is changing the developers mindset to contribute along with QAs with the automation tests and also getting support from the managers (which is something that I’ve always highlighted). If you want a team without a bottleneck and where everybody is max contributing for the quality and speed of the deliveries, then yes you need to think about a team sharing all the responsabilities and having a specilised person to guide and teach.

Basically you will see how Joel Montvelisky discusses the issues which prevents software developers to test, and what testers can do to change that.

Thank you !! See you in the next post 🙂

Using Artificial Intelligence to Speed up your Test Automation

Hey guys, today I am going to share with you this awesome webinar that I watched last weekend ! I suggest to follow IIST as they are always sharing good webinars about test.


Building a sudoku game with Kotlin

Hi guys,

Today I will continue the series of posts related to the workshop I attended during the #TechKnowday here in London. This one is to learn Kotlin building a sudoku game. So, basically Ana left available on her Github the initial parts and the solutions.

The instructions with the steps are available here. Below you can find the exercise done in parts:

You can find the first part here:

The second part:

And the third part:


If you are wondering what you have done wrong, you can check the solution for each part below. Don’t cheat, this is for after you have tried the exercise by yourself first:


Her contacts:


Thanks Ana for this workshop !


Machine Learning in IOS apps

Hello guys,

I have been to the #TechKnowday here in London three weeks ago and one of the workshops that I joined was the Machine Learning in IOS Apps. So, in the end we had a face recognition app which showed what was the emotion of the person, if the picture was someone smiling than it should show the smile emoticon and so on.

You can find the slides and follow the explanations here:

Then you will need to clone the repository with the project and download the Sentiment Polarity model here

Step 1:

In the ViewController.swift you will need to create the face detection request, the request handler and the face detection action. So you will have something like this:


Step 2:

In the SentimentAnalysisService.swift you will need to create the model using the SentimentPolarity, pass the linguistic tagger options and create the input to receive and interpret the input with the sentiment. You can add, remove or change the sentiments in the Sentiment.swift class, but don’t forget to change in this class the sentiment as well.



So, after you build, run the app and type the name of the sentiment with a space in the end, so you should have something like this:


Thanks Vasilica for this workshop !

How to integrate Guice + Cucumber + WebDriver

Hello guys,

Today I am going to post about something that I have been studying. So, in this project you can have an idea of how to implement Dependency Injection using Guice, a Google framework which helps you to reduce the need of new in your Java code. I found only projects that have only the Guice + Cucumber integration or only the Guice + Page Objects, so I think this one might be a good example of how to integrate everything.

Also, the project contains Page Objects and a Driver Factory, so you will be able to include other browsers and implement each one’s singularity when creating the browser, and also you still have the good practices of the POM.

I’ve added comments along the code, but feel free to ask anything or even suggest improvements.