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Road Runner

This library is a PoC like implementation which lets you use TestNG to run your Cucumber based BDD tests in Parallel. Well, there are already implementations and approaches available on the internet which lets you do that. So what's so special about Road-Runner.

Road-Runner unlike other implementations, lets you :

  • Run your Scenarios in parallel.
  • Provides you with a threadsafe version of the same reports that cucumber provides viz., JSON, and Html


  • JDK-8 or higher.
  • Hard-wired versions of the following cucumber artifacts:
    • info.cukes:cucumber-testng:jar:1.2.5. See here
    • info.cukes:cucumber-java:jar:1.2.5:compile. See here

Why the hard-wired dependency on Cucumber ?

The implementation hacks into the cucumber codebase and resorts to Classpath overriding[1] to hook in the support for parallel scenario execution. So if the version is upgraded, then the entire logic of parallel execution support will fall apart. This was done specifically because Cucumber implementation is Java is not thread-safe yet.

Getting started with cucumber-roadrunner.

Add a dependency to the artifact via


Create a TestNG runner that looks like below:

@CucumberOptions(plugin = {"html:output/old", "pretty:output/old/output.txt", "json:output/old/output.json"})
@Reporters(plugin = {
public class ShippingRunCukesTest extends TestNGCucumberTests {

You can provide all the options that are part of --options as detailed here via the annotation @CucumberOptions.

Cucumber-roadrunner provides one extra annotation called @Reporters. This annotation is specifically used to wire in thread-safe variants of the default cucumber reporters.

Currently the following two reporters are supported.

  1. Thread-safe HTML report.

This can be injected via "html:output/new/cucumber-html-report". This causes RoadRunner to generate the new reports in the folder output/new/cucumber-html-report. The folder value is customizable and can be changed to anything that you desire.

  1. Thread-safe JSON Report. This can be injected via "html:output/new/cucumber-html-report". This causes RoadRunner to generate the new reports in the folder output/new/ inside a file called cucumber-report.json. The folder name and file names are customizable and can be changed to anything that you desire.

Note: Both the reports have the same look and feel as that of the default reports.

Controlling parallelism.

By default this library enables scenario level parallel execution. This can be disabled via the JVM argument -Droadrunner.parallel=false.

By default the threadpool size is 10. But this can be altered to anything via the JVM argument -Droadrunner.threads=15 (This causes the threadpool size to be 15).

Further customization.

You can wire in your own threadsafe plugins (formatter or reporter) using Service Provider Interface approach.

In order to do this, here's the set of steps.

  1. Implement the interface com.rationaleemotions.PluginMapper
  2. Now either within src/main/resources (OR) src/test/resources, create a file META-INF/services/com.rationaleemotions.PluginMapper and add references of the implementation from (1) into this file.

Roadrunner will now start wiring in your threadsafe reporters as well.

[1] Classpath overriding - The process of duplicating a class from a jar to the local project, wherein the original class is created in the local project with the same project structure, but the contents are altered.


A Cucumber-TestNG variant that can execute multiple scenarios also in parallel








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