Determining when karma-pact mock server has started

Question

We're using the karma-pact plugin to run our pact JS client tests, based on the example from https://github.com/pact-foundation/pact-js/blob/master/karma/mocha/client-spec.js .

In the example there's a timeout in the before(), I believe to ensure the mock service has started before running the tests (see comment "required for slower Travis CI builds").

I'm reluctant to set a fixed timeout in our tests as it'll either be too short or too long in different environments (e.g. CI vs local) and so I was looking for a way to check if the server has started.

I'd tried using the pact API https://github.com/pact-foundation/pact-node#check-if-a-mock-server-is-running , however this appears to start a new mock server which conflicts with the one started by the karma-pact plugin (an Error: kill ESRCH error is reported when trying to run pact.createServer().running from within a test).

Is there a way to determine if the mock server has started up e.g. by waiting for a URL to become available? Possibly there's a way to get a reference the mock server started by the karma-pact plugin in order to use the pact-node API?

Matthew Fellows Matthew Fellows · Accepted Answer · 2017-05-02T23:12:16

Actually the simplest way is to wait for the port to be in use.

Karma Pact by default will start the Mock on port 1234 (and you can specify your own). Once the port is up, the service is running and you can proceed.

For example, you could use something like wait-for-host to detect the running mock service:

var waitForPort = require('wait-for-port');

waitForPort('localhost', 1234, function(err) {
  if (err) throw new Error(err);
  // ... Mock Service is up - now we can run the tests
});

Determining when karma-pact mock server has started

1 Answers