I feel like a case of deja vu so I need to write this down.

• Robolectric: simulating an Android runtime working on top of the JVM, local dev machine. No emulator needed.
• Used to be simple and straightforward. Since Robolectric 4 and recent android gradle updates, some things have been deprecated / changed making it harder to use.
• AndroidX runner “AndroidJUnitRunner” tests which go in androidTest folder: run on device or emulator, and are essentially the modern version of the instrumentation tests.
• Setup for gradle imports is highly modular. For ref:
• https://developer.android.com/training/testing/set-up-project 
• AndroidX runner “AndroidJUnit4” tests which go in androidTest folder: run on device or emulator too ⇒ the test folder name indicates which build rule is used and where the test runs.
• AndroidX runner “MockitoJUnitRunner” tests which go in the test folder: run on JVM.
• This is provided by mockito-core and is basically a JUnit runner that also happens to auto-init all the @Mock instances. ⇒ Just a convenience over the usual Mock rule, no relation to Android framework.
• How much of the Android framework can be used with that? ⇒ none
• Robolectric with AndroidX tests:
• http://robolectric.org/androidx_test/
• Use the “AndroidJUnit4” runner.
• Confusing because nothing makes it clear these are Robolectric tests.

What I have done for Cab v2:

• Build.gradle > defaultConfig > testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
• ServersActivityTest:
• @RunWith(AndroidJUnit4.class)
  @Config(application = TestMainApp.class)
  ApplicationProvider.getApplicationContext()
  ActivityScenario.launch(MainActivity.class)
• The cabv2 TestMainApp derives from the LegacyMainApp and replaces the IAppComponent by the ITestAppComponent for testing. That’s how test modules are injected in the app.

Since updating B3, I was getting errors:

• “robolectric RuntimeException Method not mocked”
• They are “solved” by adding this to app gradle:
• testOptions > unitTests >  returnDefaultValues = true
• Which in turn creates another error: “java.lang.ClassNotFoundException: android.content.res.ApkAssets”
• Real solution: following https://github.com/robolectric/robolectric/issues/4740
• The dumb solution is to remove the m2 robolectric cache so that it gets downloaded again.