Android gradle androidTestApi & testApi configuration obsoleted

This is Chris Margonis (Kudos!) answer in Kotlin-DSL:

// "base" module/project
configurations {
    create("testDependencies"){
        extendsFrom(configurations.testImplementation.get())
    }
}

dependencies {
    // example test dependency
    testImplementation "junit:junit:4.12"
    // .. other testImplementation dependencies here
}

//another module
dependencies {
    testImplementation(project(path = ":base", configuration = "testDependencies"))
}

To complement the accepted answer, in your base module :core add a configuration closure:

    // build.gradle (core module)
    configurations {  
        testDependencies.extendsFrom testImplementation  
        testRuntimeOnlyDependencies.extendsFrom testRuntimeOnly  
    }
    
    dependencies {
        def junit5_version = "5.6.0"

        // dependencies
        testImplementation "org.junit.jupiter:junit-jupiter-api:$junit5_version"  
        testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:$junit5_version"  
        testImplementation "org.junit.jupiter:junit-jupiter-params:$junit5_version" 
        testRuntimeOnly "org.junit.vintage:junit-vintage-engine:$junit5_version"
    }
    

Then in your feature module add:

    dependencies {
        implementation project(':core') {  
            testImplementation configurations.getByName('testDependencies').allDependencies  
            testRuntimeOnly configurations.getByName('testRuntimeOnlyDependencies').allDependencies  
        }
    }

Now your testing dependencies are shared across modules.

Note: Modules core and feature are fictitious, please substitute accordingly.

The way I did this was by creating a custom configuration. In your case inside the build.gradle file module A add:

configurations {
    yourTestDependencies.extendsFrom testImplementation
}

dependencies {
    // example test dependency
    testImplementation "junit:junit:4.12"
    // .. other testImplementation dependencies here
}

And in the build.gradle of module B add:

dependencies {
    testImplementation project(path: ':moduleA', configuration: 'yourTestDependencies')
}

The above will include all testImplementation dependencies declared in module A to module B.