Robolectric: Resources$NotFoundException: String resource ID with Android Gradle Plugin 3

Question

Android Studio 3.0 Beta2
classpath \'com.android.tools.build:gradle:3.0.0-beta3\'
testCompile \'org.robolectric:robolectric:3.4.2\'

Test class that

Answer 1

As mentioned by an engineer from Google team (most possibly Xavier Ducrohet), Robolectric has issues with AAPT2:

Robolectric is not compatible with aapt2.

Two options here.

First option - follow Robolectric guidelines for Android Studio 3.0+

Add the following to your build.gradle:

android {
  testOptions {
    unitTests {
      includeAndroidResources = true
    }
  }
}

Annotate your test with the Robolectric test runner:

@RunWith(RobolectricTestRunner.class)
public class SandwichTest {
}

---

Second option: disable AAPT2 adding following line into gradle.properties file:

android.enableAapt2=false

Answer 2

You can also try @Config(manifest = "<projectFolder>/src/main/AndroidManifest.xml") in the case that you can not simply include the resources as some projects tests will fail with that included.

Answer 3

Not a direct answer to the question, but if you are testing something that needs a context to query resources against I have found the following to work quite well:

ApplicationProvider.getApplicationContext()

(or RuntimeEnvironment.application -- but this is deprecated in favor of the above)

Answer 4

I was using espresso, and for that you needed to use app resources, not test resources.

So instead of

InstrumentationRegistry.getInstrumentation().context.resources.getString("key")

I used

activityRule.activity.getString("key")

Answer 5

(for anyone that might be looking for a solution to a similar problem)

---

Be sure to use

RuntimeEnvironment.application

and not:

RuntimeEnvironment.systemContext

when you're trying to resolve resources "manually".

That's one case in which Resources$NotFoundException might show up with Robolectric.

Answer 6

If your build fails due to an AAPT2 resource processing issue or you want to use Roboelectric, you can disable AAPT2 by setting android.enableAapt2=false in your gradle.properties file and restarting the Gradle daemon by running ./gradlew --stop from the command line.

Official guideline Android Studio 3.0 Release