Hilt: handle Services with injection automatically started in instrumentation tests

Let’s assume I have a service that is automatically started at the app startup and it is required by some third party library. This service needs some fields to be injected in the onCreate method.

@AndroidEntryPoint
class MyMessagingService : FirebaseMessagingService() {
  @Inject internal lateinit var dep1: Dep1
  @Inject internal lateinit var dep2: Dep2
  ...
}

Then I have a @HiltAndroidTest that runs hiltRule.inject() in its @Before function.

@AndroidEntryPoint
class MyTest {
  @get:Rule val hiltRule = HiltAndroidRule(this)
  @Before fun inject() {
    hiltRule.inject()
  }
  ...
}

Unfortunately, the way Hilt injection works in tests generates a race condition between hiltRule.inject() and MyMessagingService#onCreate. If the latter gets executed before hiltRule.inject() the test will crash because dependency graph has not been created yet.

How can I avoid this issue?

[francescocervone]

@bcorso the original issue is fixed by using a combination of @EarlyEntryPoint and the solution proposed here -> https://github.com/google/dagger/issues/2016#issuecomment-685057959

---

@ReginFell usually the No instrumentation registered error appears when you are trying to test code dependent on the android framework on the JVM but you forgot to annotate the test class with

import androidx.test.ext.junit.runners.AndroidJUnit4
import org.junit.runner.RunWith

@RunWith(AndroidJUnit4::class)
class TestClass {  }

Of course you need Robolectric in order to make the test pass on the JVM. It should be unrelated to @EarlyEntryPoint annotation.

[bcorso]

FWIW, we’re considering loosening these restrictions a bit.

Basically, we want to allow you to use EntryPoints.get() before your test instance is created. While this would lead to a runtime exception if your entry point depends on an @BindValue, the error message should be pretty clear (e.g. Dagger will tell you that generated @Provides for the particular @BindValue field returned null when it should have been non-null).