JaCoCo shows 0% coverage, even all tests had passed

Question

1. I have written some test cases under androidTest directory.
2. I am using androidx (testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner")

3. added dependencies:

   androidTestImplementation 'androidx.test:runner:1.1.0'

   androidTestImplementation 'androidx.test:rules:1.1.0'

4. added JaCoCo as dependency, as well.

5. When I run createDebugAndroidTestCoverageReport Gradle task, all the test cases run successfully but coverage is 0% in report

I am guessing that is due to this error:

V/InstrumentationResultParser: Error: Failed to generate Emma/JaCoCo coverage. V/InstrumentationResultParser: INSTRUMENTATION_CODE: -1

Answer 1

Google just redirected me to my own answer ...

As it turned out, for Android projects one (meanwhile) has to use a path alike this:

"${project.buildDir}/intermediates/javac/debug/classes"

In case you may wonder... JaCoCo only works for @RunWith(JUnit4.class) Java unit tests in test (but not @RunWith(AndroidJUnit4.class) Android integration tests in androidTest).