Add integration tests

[nuest]

Currently the package has no test - but it is really useful to me, so I'll add this "request" knowing that I'll probably have to do this myself :-)

Since this package really needs an actual MongoDB and Elasticsearch to be tested, integration tests could run both of these databases in Docker containers and then insert data into the MongoDB and check that they are available in Elasticsearch.

Here are some links that could get somebody started on this task:

• use compose and a script (start the containers "around" the tests) https://hharnisc.github.io/2016/06/19/integration-testing-with-docker-compose.html
• use dockerode (start the containers from within the script) https://www.npmjs.com/package/dockerode

[toystars]

@nuest are you still on the test or should I get along with it?

[nuest]

I haven't started on this yet, so if you want to give it a go, please do.