Robolectric AndroidX fragments NoClassDefFoundErro

Question

After migration of code and tests to AndroidX, all seems to work pretty well, however Robolectric junit tests for two fragments are failing due to NoClassDefFoundError: androidx/fragment/testing/R$style exception. The stack trace:

java.lang.NoClassDefFoundError: androidx/fragment/testing/R$style at androidx.fragment.app.testing.FragmentScenario$EmptyFragmentActivity.onCreate(FragmentScenario.java:79) at android.app.Activity.performCreate(Activity.java:5933) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105) at androidx.test.runner.MonitoringInstrumentation.callActivityOnCreate(MonitoringInstrumentation.java:674) at org.robolectric.android.controller.ActivityController.lambda$create$0(ActivityController.java:69) at org.robolectric.shadows.ShadowLooper.runPaused(ShadowLooper.java:365) at org.robolectric.android.controller.ActivityController.create(ActivityController.java:69) at org.robolectric.android.controller.ActivityController.create(ActivityController.java:74) at org.robolectric.android.internal.LocalActivityInvoker.startActivity(LocalActivityInvoker.java:39) at androidx.test.core.app.ActivityScenario.launch(ActivityScenario.java:207) at androidx.fragment.app.testing.FragmentScenario.internalLaunch(FragmentScenario.java:283) at androidx.fragment.app.testing.FragmentScenario.launchInContainer(FragmentScenario.java:265)

For testing fragments I'm using FragmentScenario, and it seems the FragmentScenario.EmptyFragmentActivity refers to a missing R class from a package androidx.fragment.testing.R:

setTheme(getIntent().getIntExtra(THEME_EXTRAS_BUNDLE_KEY, R.style.FragmentScenarioEmptyFragmentActivityTheme));

Any idea what might be wrong? Maybe I'm missing a dependency that's not that obvious to me.

Reproducible in following project: https://github.com/marcinbak/androidx-test-error

Also reported in Google's issue tracker: https://issuetracker.google.com/issues/122321150

Answer 1

According to answer from Google it is required to include androidx_fragment_test (androidx.fragment:fragment-testing:1.1.0-alpha03) artifact in the testing APK (not in instrumentation APK or testing dependency).

What this means it has to be added as debugImplementation androix_fragment_test in your build.gradle file.

If you also run tests on release target then you have to add implementation androix_fragment_test.

You can see the whole conversation in Google's issue tracker: https://issuetracker.google.com/issues/122321150