Feature: Add assertion test framework best practice for Android using AssertJ-Android

[ghost]

@futurice Hey there! I have added best practices on asserting Android specific components in Android tests. Let me know what you like and your reasoning if you don't. Thanks!

[Tony---Zhang]

I prefer AssertJ too~

[peter-tackage]

I'm also an AssertJ fan, I had it somewhere in my mind to include a reference to it in an updated testing section (that section is really dated now). I'd be inclined to mention that the key point is that there are libraries out there to make more powerful assertions (also note: https://github.com/google/truth)

[ghost]

@peter-tackage Thanks for the response, you are correct about Truth, and for me personally keeping your projects to use purely Google dependencies is a big yes. I have recently stumbled across Truth and found it very similar to using AssertJ (both using Hamcrest matchers). I have not noticed Truth power yet with Android, as I find AssertJ-Android is currently more geared towards Android. I would love to help adding Android specific extensions to Truth, it is however a big task and not a days work with my current schedule.

Lastly please could you post back the link to the up to date testing section so I may familiarize myself with it. Much appreciated.

[peter-tackage]

I don't know if I'd go as far as advocating Google-only dependencies. Google can still be quite fickle with some of their non-official Android / Java libraries. Picking future trend or winners in libraries is a difficult task; having a big name backer is one dimension, but certainly no guarantee. Is anyone using Agera rather than RxJava?

[ghost]

@peter-tackage It is definitely a difficult task picking libraries as there is so many out there mostly bad but a lot of good ones, and my reasoning behind pure Google dependencies is that Google is there to stay, I am however open minded to try anything new, going to look at Agera, and try it out definitely! Thanks for the mention!