Speed up BDD with Parallel Cucumber

Shashikant Jagtap

Running Cucumber in Parallel

First of all, if you using Cucumber as a BDD tool and having large feature set, then you are at the right place.  Now we have an awesome Ruby Gem called ‘Parallel_tests’ which is going to make our life much easier by parallelising large set of feature to run much faster. You can read more ‘Parallel_tests’ on GitHub.

In this short tutorial, we will see how to use ‘Parallel_tests’ in our project and how to aggregate generated html cucumber reports.

We will use source code from my GitHub repository ‘Cuke_Experiment‘. Please download source code if you have development environment ready

$ git clone https://github.com/Shashikant86/Cuke_Experiment
$ cd Cuke_Experiment

You need to have Ruby 2.0.0 for this demonstration.

Using Parallel_Tests Gem

Parallel_Tests is a Ruby Gem for running RSpec, Cucumber and Test::Unit on multiple CPUs in the parallel to speed up tests. There are many benefits using Parallel_Tests Gem into your Cucumber.

  • It is very easy to use in your existing project or test suite
  • Parallel Tests forks cucumber into number of CPUs processes and you can specify number of processes.
  • Parallel Tests can generate separate reports for each process using variable ‘ENV[‘TEST_ENV_NUMBER’]’
  • You don’t need to change your test options. Just keep everything inside  ‘-o “your test profiles’

Installing Gem

You can just run following command to install parallel_tests gem into your existing project

$ gem install parallel_tests

OR Simply add it in your Gemfile.

$ vim Gemfile

And add following line

gem "parallel_tests"

Now, you need to install bundler.

$ bundle install

That’s it. You are now ready to use parallel_tests into your project.

Using Gem

Once you have successfully installed parallel_tests Gem then you are now ready to use it. By default, it forks cucumber into 4 processes depending on number of feature files. If number of feature files are less than 8 then it usually use 2 processes.

$ bundle exec parallel_cucumber features/

Now that, this command will run all your feature files within the ‘features’ directory.

Running features from sub-directories

You can run specific set of features from sub-directories by navigating to that directory.

$ bundle exec parallel_cucumber features/homepage_features/

Running features with specific profiles or tags

You can run parallel_tests y using specific profiles or tags using test options  ‘- o’

$ bundle exec parallel_cucumber features/ -o "-p stage -t @sanity"

 Running features by specifying number of processes

You can specify number of processes to speed up feature executions by using option ‘-n’

$ bundle exec parallel_cucumber features/ -n 8

This will break down features into 8 different processes.

Generating HTML Reports

We can easily generate HTML reports for the each process and aggregate reports for each process. As we said earlier that there is a variable ENV[‘TEST_ENV_NUMBER’] which gives details about all the process that cucumber scenarios are executing.

In order to generate reports for all the processes, we need to create a profile in our ‘cucumber.yml’. Let’s call this profile ‘default’ profile.

default: --format html --out report<%= ENV['TEST_ENV_NUMBER'] %>.html

This will create HTML report for each process and name it as report.html, report2.html and so on.

Source Code & Quick Start

Source code available on GitHub ‘Cuke_Experiment‘ , Download it and get started. I assume, you have Ruby development environment ready(RVM, XCode, Homebrew etc etc)

$ git clone https://github.com/Shashikant86/Cuke_Experiment
$ cd Cuke_Experiment
$ rvm use 2.0.0
$ bundle install
$ bundle exec parallel_cucumber features/

It will execute all the features in 2 different processes and generate report.html and report2.html. My i-Term look like this:

Parallel_Cucumber

 

Watch Video Demo

You can watch in action in the following Video

 

 

 

HAPPY BDD !!