Add E2E tests to ensure zipkin-js is usable in the browser

[DanielMSchmidt]

We have the problem that we sometimes merge PRs which add functionality in a way that the entire zipkin library is unusable in the browser (I think there was only one usable version of it, afaik). To prevent us from doing so we need E2E tests, but very simple ones would be sufficient.

We could use cypress to open a browser, click on a button in a create-react-app which just triggers one span to be recorded to the console or to a server. That would already help a lot with making sure we don't break things moving forward.

[jcchavezs]

This is a terrific idea Daniel! I had a similar idea but since my knowledge about JS is limited I implemented a E2E test in zipkin-js-example which runs every night against the master version of zipkin-js. This is rudimentary but at least worked as smoke test: https://github.com/openzipkin/zipkin-js-example/blob/master/.circleci/config.yml

Your idea sounds more professional and I would be more than happy to help if you wanna start with it!

[DavideCarvalho]

@DanielMSchmidt I was thinking the same thing, really nice that this issue is open. Do you know if the zipkin library is broken, it will break the app too?