Update
You should no longer encounter this error if youre using the latest gradle version.
I also encountered this issue.
If you look at migrating to Robolectric 4.0 here, it suggest to add the following line in your gradle.properties.
android.enableUnitTestBinaryResources=true
The problem is that, if you add this you your gradle.properties, it will output this warning:
WARNING: The option setting
‘android.enableUnitTestBinaryResources=true’ is experimental and
unsupported.
Now, if you look at Robolectric releases here. You could see that this is a known issue where they state that
Android Gradle Plugin may report the following warning, which may be safely ignored: WARNING: The option setting ‘android.enableUnitTestBinaryResources=true’ is experimental and unsupported.. Android Gradle Plugin 3.4 will resolve this issue.
I believe unless you could update you gradle to 3.4. You won’t be able to solve this issue.
What I did instead was to include Robolectric 4.0 as dependency.
testImplementation "org.robolectric:robolectric:4.0.2"
and annotate my test class with
@RunWith(RobolectricTestRunner::class)
This should make your test work.
Now when you run the test, you’ll notice that Robolectric will log the following:
[Robolectric] NOTICE: legacy resources mode is deprecated; see
http://robolectric.org/migrating/#migrating-to-40
Ignore this for now but as soon as you could update your gradle, migrate to the new Robolectric testing.