Disable 'testOnly' mode for Android Studio 3.0
Android Studio 3.0 sets
android:testOnly="true" automatically on APKs that are ran from the IDE.
However, for some devices (such as OPPO R11), the test-only APKs can never be installed ...
If you face the same problem, try add this line to your '/gradle.properties':
# gradle.properties android.injected.testOnly=false
Then the boring
android:testOnly attribute disappears. ( ͡° ͜ʖ ͡°)✧
BTW, if you do not have an 'OPPO R11' (congratulations), and just want to install such a test-only app with
adb install -t <test_only_apk_filename>.apk
Otherwise, you will get a failure message:
Failed to install app-debug.apk: Failure [INSTALL_FAILED_TEST_ONLY: installPackageLI]