Unit Testing android fragments and activity with Hilt and Robolectric

In this blog, which will be a short one I'll discuss how to test Fragments and Activities.

The problem is that you can't use the standard launchInContainer when talking about Hilt activities. Especially so because Robolectric has it's own way of creating Activities which are NOT annotated with @AndroidEntryPoint.

OK, as an example we'll create a new application, and within this project we'll test the activity.

I'll test detailing the process as we go. Let's start:

1. Create new project named Hilt Test Robolectric
2. Add hilt to the project https://developer.android.com/training/dependency-injection/hilt-android
3. Add Robolectric http://robolectric.org/getting-started/
4. Add a fragment

First we create a new fragment, I'll create it with the xml:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".BlankFragment">

    <TextView
        android:id="@+id/tv_blank"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="Hello From Blank" />

</FrameLayout>

And the Kotlin Class:

class BlankFragment : Fragment() {

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        return inflater.inflate(R.layout.fragment_blank, container, false)
    }
}

Now Let's test this:

First to use launchInContainer we should add the dependency:

debugImplementation "androidx.fragment:fragment-testing:1.3.6"

Now, we can write our first test:

@HiltAndroidTest
@RunWith(RobolectricTestRunner::class)
@Config(
    manifest = Config.NONE,
    sdk = [Build.VERSION_CODES.O_MR1],
)
class BlankFragmentTest {

    @Test
    fun testMainActivity() {
        val frag = launchFragmentInContainer<BlankFragment>()

        frag.onFragment {
            assert(it.view?.findViewById<TextView>(R.id.tv_blank)?.text.toString() == "Hello From Blank")
        }
    }
}

And here we find our problem, the one we are tying to fix:

Hilt Fragments must be attached to an @AndroidEntryPoint Activity. Found: class androidx.fragment.app.testing.FragmentScenario$EmptyFragmentActivity

Fixing this

First we create a new source set debug. and we add HiltTestActivity into it.

Since our package is de.sixbits.testrobolectrichilt we can create the HiltTestActivity inside src/debug/de/sixbits/testrobolectrichilt .

Now, in that package we can add the HiltTestActivity Like:

@AndroidEntryPoint
class HiltTestActivity : AppCompatActivity() {
}

Now in src/debug we'll create an android Manifest and add this activity to it like:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="de.sixbits.testrobolectrichilt">

    <application>
        <activity
            android:name=".HiltTestActivity"
            android:exported="true" />
    </application>
</manifest>

Next, we will create a helper Kotlin Extension which will inflate the fragment in this activity like:

inline fun <reified T : Fragment> launchFragmentInHiltContainer(
    fragmentArgs: Bundle? = null,
    @StyleRes themeResId: Int = R.style.FragmentScenarioEmptyFragmentActivityTheme,
    crossinline action: Fragment.() -> Unit = {}
) {
    val startActivityIntent = Intent.makeMainActivity(
        ComponentName(
            ApplicationProvider.getApplicationContext(),
            HiltTestActivity::class.java
        )
    )

    ActivityScenario.launch<HiltTestActivity>(startActivityIntent).onActivity { activity ->
        val fragment: Fragment = activity.supportFragmentManager.fragmentFactory.instantiate(
            Preconditions.checkNotNull(T::class.java.classLoader),
            T::class.java.name
        )
        fragment.arguments = fragmentArgs
        activity.supportFragmentManager
            .beginTransaction()
            .add(android.R.id.content, fragment, "")
            .commitNow()

        fragment.action()
    }
}

And now we are going to change the test to be like:

@HiltAndroidTest
@RunWith(RobolectricTestRunner::class)
@Config(
    manifest = Config.NONE,
    sdk = [Build.VERSION_CODES.O_MR1],
    application = HiltTestApplication::class
)
class BlankFragmentTest {
    @get:Rule
    val hiltAndroidRule = HiltAndroidRule(this)

    @Test
    fun testMainActivity() {
        launchFragmentInHiltContainer<BlankFragment> {
            assert(
                this.view?.findViewById<TextView>(
                    R.id.tv_blank
                )?.text.toString() == "Hello From Blank"
            )
        }
    }
}

And now we have a working test!

The application and it's source is located at:

https://github.com/MickSawy3r/testrobolectrichilt