Coddee test example

README.md

Coddee test example

An example code from coddee. These are a set of tests written using mocha and chai.

In webhook_method_tests.js, I am testing that the method saves a MongoDB document into a collection.

In webhook_tests.js, I am testing that this method is called when a webhook comes in from GitHub.

I wrote two different tests because the middleware that detects the GitHub webhook is an event emitter, and I don't have much control over how long it takes to actually save a document to a collection. The fact that I am testing an asynchronous middleware means that I have to use setTimeout to make my assertion. Also, write operations are not always cheap, and I have to delay my assertion for quite a bit (~800ms), which is unacceptable if you have a large test suite. In spite of the significantly delayed assertion, the test would be still brittle because sometimes DB operation might take longer than my delay.

I addressed the problem of delayed assertion by separating the tests: one for testing that the correct method is called, and another for testing that the method saves the data in the db. In the first one, I still need to use setTimeout, but the delay is only 50ms, and the test is very solid.

webhook_method_tests.js

MochaWeb.testOnly(function(){
  var sinon = Meteor.npmRequire('sinon');
  // This is how you require an npm package in Meteor

  describe("webhook methods", function(){
    beforeEach(function() {
      sinon.stub(Coddee.parser, 'getDiff');
      sinon.stub(Coddee.parser, 'persistDiff');
    });

    afterEach(function() {
      Repos.remove({});
      PullRequests.remove({});
      Revisions.remove({});
      Coddee.parser.getDiff.restore();
      Coddee.parser.persistDiff.restore();
    });

    describe("opened", function(){
      it("creates a pullRequest document and a revision", function(){
        var payload = JSON.parse(
          Assets.getText('fixtures/github_webhook/pull_request/opened.txt')
        );

        FactoryBoy.create('userRepo', {repoId: payload.pull_request.base.repo.id});
        // FactoryBoy is an open source project I initiated.
        
        Coddee.webhook.pr.opened(payload);

        chai.expect(PullRequests.find().count()).to.equal(1);
        chai.expect(Revisions.find().count()).to.equal(1);
      });
    });
    
    // ...
    
  });
});

webhook_tests.js

var generateSignature = function (payload) {
  var crypto = Npm.require('crypto');
  var hmac = crypto.createHmac('sha1', Meteor.settings.GitHubWebhookSecret); // Meteor.settings is how you can safely access secret variables without committing them to the version control in Meteor

  hmac.update(JSON.stringify(payload));

  return 'sha1=' + hmac.digest('hex');
};

MochaWeb.testOnly(function(){
  var sinon = Meteor.npmRequire('sinon');

  describe("pull_request webhook", function(){
    afterEach(function() {
      Repos.remove({});
      PullRequests.remove({});
      Revisions.remove({});
    });

    describe("opened", function(){
      it("calls Coddee.webhook.pr.opened with payload", function(done){
        var mock = sinon.mock(Coddee.webhook.pr);
        mock.expects('opened');

        var endpointUrl = Meteor.absoluteUrl('webhook');
        var payload = JSON.parse(
          Assets.getText('fixtures/github_webhook/pull_request/opened.txt') // Get a test fixture
        );
        var headers = {
          'Request URL': endpointUrl,
          'Request method': 'POST',
          'content-type': 'application/json',
          'Expect': '',
          'User-Agent': 'GitHub-Hookshot/4963429',
          'X-GitHub-Delivery': 'c9441380-4609-11e5-9099-2600e79e587b',
          'X-GitHub-Event': 'pull_request',
          'X-Hub-Signature': generateSignature(payload)
        };

        FactoryBoy.create('userRepo', {repoId: payload.pull_request.base.repo.id});

        HTTP.post(endpointUrl, {
          headers: headers,
          data: payload
        });

        // Meteor.bindEnvironment is needed because almost everything in Meteor runs on Fiber
        // and we need to run the callback on the proper Fiber to avoid unexpected behaviors.
        Meteor.setTimeout(Meteor.bindEnvironment(function () {
          mock.verify();
          done();
        }), 50);
      });
    });
    
    //...
    
  });
});