CircleCI’s parallelization: junit tests with Gradle

balancing.sh

#!/usr/bin/env bash
testFiles=$(find ./{app}/src/test/java/{your}/{package}/{name} -name '*.java' | sort | awk "NR % ${CIRCLE_NODE_TOTAL} == ${CIRCLE_NODE_INDEX}")
./gradlew test -PtestFilter="$testFiles"

build.gradle

testOptions {
        unitTests.all {
            if (project.hasProperty("testFilter")) {
                ArrayList props = project.getProperties().get("testFilter")
                        .replaceAll("./app/src/test/java/{your}/{package}/{name}/", "**/")
                        .replaceAll(".java", ".class")
                        .split("\\s+")

                for (String item : props) {
                    include item
                }
            }
        }
    }

circle.yml

test:
  override:
    - sh ./balancing.sh:
        parallel: true