Hilt: No JaCoCo test coverage on @AndroidEntryPoint classes.

Given a class

@AndroidEntryPoint
MyActivity : AppCompatActivity()

and a test class

@HiltAndroidTest
@RunWith(RobolectricTestRunner::class)
@LooperMode(LooperMode.Mode.PAUSED)
class MyActivityTest() {
    private lateinit var scenario : ActivityScenario<MainActivity>

    @Rule
    @JvmField
    val rule : HiltAndroidRule = HiltAndroidRule(this)

    @Before
    fun setup() {
        rule.inject()
        scenario = ActivityScenario.launch(MyActivity::class.java)
    }

    @Test
    fun myActivityTest() {
        scenario.onActivity { activity: MyActivity ->
        // test code
        }
   }
  // .. rest of test class
}

and given JaCoCo Gradle Plugin version 0.8.5

Expected: Some code coverage on MyActivity class. Actual:: 0% coverage

Notes:

• The coverage worked fine before the hilt plugin migration
• Given the same scenario with @AndroidEntryPoint MyActivity : MyActivityBase() where class ÀctivityBase : AppCompatActivity() There is coverage reported on ActivityBase but not on MyActivity.

This is surely to do with the fact that Hilt is adding an injecting class between MyActivity and it’s super class.

This is a Generic example, please tag me if you require any more information.

[goldy1992]

A useful note for anyone having trouble with this using Android Gradle Plugin (AGP) 4.1. In order to get any unit test code coverage with JaCoCo you need to testCoverageEnabled false so that AGP’s compiled classes for use on device are not used instead of the local instrumented classes.

See https://issuetracker.google.com/issues/171125857 and AGP 4.1 release notes on unit tests https://developer.android.com/studio/releases/gradle-plugin

[goldy1992]

@Chang-Eric this does indeed provide a workaround… Due to the vague explanation in the link you provided, I will demonstrate this with an example for an activity:

@AndroidEntryPoint(AppCompatActivity::class)
class MainActivity : Hilt_MainActivity() {
 // contents of class
}

@HiltAndroidTest
@RunWith(RobolectricTestRunner::class)
@LooperMode(LooperMode.Mode.PAUSED)
class MainActivityTest {

    private lateinit var scenario : ActivityScenario<MainActivity>

    @Rule
    @JvmField
    val rule : HiltAndroidRule = HiltAndroidRule(this)

    @Before
    fun setup() {
        rule.inject()
        scenario = ActivityScenario.launch(MainActivity::class.java)
    }

    @Test
    fun myTest() {
    }
}

This declaration allows JaCoCo to know of the existence of the generated Hilt_MainActivity class… This is a workaround as we end up having to refer to generated code from our real code, which doesn’t seem to cause to much trouble on my Android Studio 4.0.1 however will probably cause havoc on previous versions and/or other IDEs.