This is a quick little note as I forget how to easily setup an enviroment which allows me to use Retrofit to interface with a remote API and easily swap out the API implementation when testing to swap in canned responses from MockWebServer or Mockito

I imagine there are many approaches to achieve the same goal so I would be interested to hear of anyone elses.

Step 1 - Gradle setup

Step 2 - Create Retrofit API interface

See the Retrofit site

Step 3 - Create ApiModule Provider class for DI

This Module class is whats used to satisfy the runtime production api dependency via Dagger

Step 4 - Init Dagger in Application class

I am using a custom DaggerHelper class than makes it easy to swap the production and test modules. This needs to be init with DaggerHelper.initProductionModules(); in the Application.onCreate()

Step 5 - Inject any classes

Add @Inject to any class fields that are provided by a module and call DaggerHelper.inject(this) from the class constructor. See Dagger docs for more.

Step 6 - Create a test

Step 7 - Party!