Add unit tests

[carlosms]

We should have as many unit tests as makes sense.
When possible, all features that can be tested with unit tests instead of integration tests will save time.

[smacker]

I added tests to internal packages. My idea was to also add some tests for cmd package with mocked docker dependency but as I'm not working on it right now, I'm returning the issue into todo.

[se7entyse7en]

@kyrcha will start looking into this so that we can also familiarize with the project. @kyrcha do you mind self-assigning yourself this card then?

[kyrcha]

@se7entyse7en Sure. Could you add the QA team to the repo and also to the metadata because I cannot do the assignment myself?
Related issue: src-d/metadata-retrieval#13

[se7entyse7en]

@se7entyse7en Sure. Could you add the QA team to the repo and also to the metadata because I cannot do the assignment myself?

\cc @smola what's the policy here? maybe QA should be part of all repos by default?

[se7entyse7en]

@kyrcha I'll manually add you for now 👍

[smola]

@se7entyse7en We have pending some automation of GitHub permissions by infra. Other than that, please add QA team with Write permission to any repository on demand. Thanks!