Android multi module test dependency - unit-testing

Question

With Android Studio 3.0 / android_gradle_version = '3.0.1' / gradle-4.5
Let's say I have two android modules
module-base
module-a
When I want to access sources from module-base in module-a , I just need to write this in my
module-a.gradle
dependencies {
implementation project(path: ':module-base')
}
But, what if I want to access test sources from module-base in test of module-a?
Here does not work approach like above
dependencies {
testImplementation project(path: ':module-base')
}
I found lot of advices (few years old) which says something like
compileTestJava.dependsOn tasks.getByPath(':module-base:testClasses')
testCompile files(project(':module-base').sourceSets.test.output.classesDir)
or
testCompile project(':module-base).sourceSets.test.classes
But no one from mentioned works. There is always something wrong from the compiler point of view :-/
Can you someone help me how to create Android test code dependency between two modules?

Answer 1

In case anyone else ends up here, one way to accomplish this is to define the target module as a source set. Let's assume test-mdoule is the module we want to import stuff from, we can do it this way:
android {
sourceSets {
// non-instrumental test example
test {
java.srcDir project(":test-module").file("src/test/java")
}
// instrumental test example
androidTest {
java.srcDir project(":test-module").file("src/androidTest/java")
}
}
}
Reference: https://jonnycaley.medium.com/sharing-test-code-in-a-multi-module-android-project-7ce4de788016

Answer 2

Actually I find just workaround for this. Don't use test sources from module-base but use sources from test related module module-testutils which is defined like this
dependencies{
testImplementation project(':module-testutils')
}
Thus you can share common test code which will be excluded for non-testable apk.