Demo setup and pact workflow

Initial setup

First modify your /etc/hosts file and add following entries:

127.0.0.1	pacts.spaceships.site
127.0.0.1	www.spaceships.site
127.0.0.1	admin.spaceships.site
127.0.0.1	service.spaceships.site

Then startup docker containers in your terminal with docker-compose build && docker-compose up. When all containers are built and run, you can navigate to www.spaceships.site and admin.spaceships.site and check that the applications are working correctly.

Afterwards cd into the three node applications and in each one run npm install

Test interactions

There are sample interactions for spaceship-creator-app in spaceship-creator-app/src/api/spaceships.interactions.js that are used in spaceship-creator-app/src/api/api.spec.js. Via these interactions and unit tests you can create the first pact by running npm run test in the spaceship-creator-app. This will generate a pact in spaceship-creator-app/pacts/output that you can publish to the pact broker via npm run pacts:publish. You can find the pact broker here.

A similar workflow can be used to create pacts for spaceships-viewer. Interactions and unit tests can be found in spaceships-viewer/routes/common, when you run npm run test && npm run pacts:publish in /spaceships-viewer your pacts are generated and put to the broker.

Verification

To verify the pacts in the pact broker, the spaceships-service uses the script spaceships-service/pacts/provider.spec.js. With npm run pacts:verification in /spaceships-service the service will download the pacts from the broker and verify them by testing each interaction (calling the defined endpoint) in the service itself. Results will also be published back to the pact broker.

Breaking the Verification

If you want to test what happens, when you break one of the pacts, let's say we replace the current getSpaceships endpoint with one that also returns pagination data. You can replace the getSpaceshipsInteraction in spaceships-viewer/routes/common/spaceships.interactions.js with following code:

const getSpaceshipInteraction = {
  consumer: 'spaceship-viewer',
  provider: 'spaceships-service',
  interaction: {
    state: 'there is a spaceship with id 1 in the database',
    uponReceiving: 'a request to get all spaceships',
    withRequest: {
      method: 'GET',
      headers: {
        'Content-Type': 'application/json',
      },
      path: '/spaceships',
    },
    willRespondWith: {
      status: 200,
      headers: {
        'Content-Type': 'application/json; charset=utf-8',
      },
      body: {
        itemsPerPage: Matchers.somethingLike(1),
        page: Matchers.somethingLike(1),
        totalItems: Matchers.somethingLike(1),
        items: Matchers.eachLike({
          id: Matchers.somethingLike(1),
          name: Matchers.somethingLike('A spaceship'),
          description: Matchers.somethingLike('Spaceship description'),
          size: Matchers.somethingLike('small'),
        }, {
          min: 1,
        }),
      }
    },
  },
};

Now also update the test for this interaction in spaceships-viewer/routes/common/handlers.spec.js by switching

expect(req.getSpaceshipsResult[0].id).toEqual(1);

with

expect(req.getSpaceshipsResult.page).toEqual(1);

This will make sure that instead of testing for an array in the get spaceships endpoint, it tests for the added pagination metadata.

Now rerun the tests for spaceships-viewer and publish your pacts.

The last update is in spaceships-service. In spaceships-service/routes/spaceships/handlers.js replace

function getSpaceships(req, res) {
  return res.json(spaceships.getItems());
}

with

function getSpaceships(req, res) {
  return res.json(spaceships.getPaginatedItems());
}

If you now retry to verify your pacts on the broker, verification should work for the viewer app but not for the creator-app anymore.

Reset

If you want to reset the changes done in the last steps, in spaceships-service simply run npm run reset. This will reset the database, clear the pact broker from all interactions and reset the files to their initial implementations