Robolectric runtime dependencies downloader

build-robolectric.gradle

/**
 * Module that includes this will be configured to use offline dependencies for Robolectric
 * This downloads robolectric dependencies once into the root project
 */

def robolectricDependenciesFolder = rootProject.buildDir.path + "/robolectric-dependencies"

// configuration that resolves Robolectric runtime dependencies
configurations.create('robolectricRuntime')

// explicitly name required runtime dependencies
dependencies {
// runtime dependencies for org.robolectric:robolectric:3.0
    robolectricRuntime "org.ccil.cowan.tagsoup:tagsoup:1.2"
    robolectricRuntime "org.robolectric:android-all:4.1.2_r1-robolectric-0"
    robolectricRuntime "org.robolectric:shadows-core:3.0:16"
    robolectricRuntime "org.json:json:20080701"
}

rootProject.task(type: Copy, overwrite: true, "downloadRobolectricDependencies") {
    println "downloadRobolectricDependencies " + robolectricDependenciesFolder
    from configurations.robolectricRuntime
    into robolectricDependenciesFolder
}

tasks.all {
    if (it.name.startsWith("test")) {
        it.dependsOn(rootProject.tasks.findByName("downloadRobolectricDependencies"))
    }
}

// tests have own system properties, cannot be set from gradle via -D
android {
    testOptions {
        unitTests.all {
            systemProperty 'robolectric.offline', 'true'
            systemProperty 'robolectric.dependency.dir', robolectricDependenciesFolder
        }
    }
}

it doesn't work...