Skip to content


Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?
This branch is 1933 commits behind cucumber:main.

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time

Build Status Gem Version Dependency Status Code Climate Join the chat at

Aruba is Cucumber extension for testing command line applications. Features at a glance:

  • Test any command line application, implemented in any language
  • Manipulate the file system
  • Automatically reset state of file system between scenarios



If you have a Gemfile, add aruba. Otherwise, install it like this:

gem install aruba

Then, require the library in one of your ruby files under features/support (e.g. env.rb)

require 'aruba/cucumber'

You now have a bunch of step definitions that you can use in your features. Look at lib/aruba/cucumber.rb to see them all. Look at features/*.feature for examples (which are also testing Aruba itself).


Originally written for cucumber, aruba can be helpful in other contexts as well. One might want to use it together with rspec.

  1. Create a directory named spec/support
  2. Create a file named spec/support/aruba.rb with:
require 'aruba/rspec'
  1. Add the following to your spec/spec_helper.rb
Dir.glob(::File.expand_path('../support/*.rb', __FILE__)).each { |f| require_relative f }
  1. Add a type to your specs
RSpec.describe 'My feature', type: :aruba do
  # [...]


aruba provides a wonderful API to be used in your tests:

  • Creating files/directories
  • Deleting files/directories
  • Checking file size
  • Checking file existence/absence
  • ...

A full documentation of the API can be found here.


Aruba has some default behaviour that you can change if you need to.

Use a different working directory

Per default Aruba will create a directory tmp/aruba where it performs its file operations. If you want to change this behaviour put this into your features/support/env.rb:

Before do
  @dirs = ["somewhere/else"]

Modify the PATH

Aruba will automatically add the bin directory of your project to the PATH environment variable for the duration of each Cucumber scenario. So if you're developing a Ruby gem with a binary command, you can test those commands as though the gem were already installed.

If you need other directories to be added to the PATH, you can put the following in features/support/env.rb:

ENV['PATH'] = "/my/special/bin/path#{File::PATH_SEPARATOR}#{ENV['PATH']}"

Increasing timeouts

A process sometimes takes longer than expected to terminate, and Aruba will kill them off (and fail your scenario) if it is still alive after 3 seconds. If you need more time you can modify the timeout by assigning a different value to @aruba_timeout_seconds in a Before block:

Before do
  @aruba_timeout_seconds = 5

Increasing IO wait time

Running processes interactively can result in race conditions when Aruba executes an IO-related step but the interactive process has not yet flushed or read some content. To help prevent this Aruba waits before reading or writing to the process if it is still running. You can control the wait by setting @aruba_io_wait_seconds to an appropriate value. This is particularly useful with tags:

Before('@slow_process') do
  @aruba_io_wait_seconds = 5


Aruba defines several tags that you can put on on individual scenarios, or on a feature.

Seeing more output with @announce-*

To get more information on what Aruba is doing, use these tags:

  • @announce-cmd - See what command is run
  • @announce-stdout - See the stdout
  • @announce-stderr - See the stderr
  • @announce-dir - See the current directory
  • @announce-env - See environment variables set by Aruba
  • @announce - Does all of the above

Adding Hooks

You can hook into Aruba's lifecycle just before it runs a command:

Aruba.configure do |config|
  config.before_cmd do |cmd|
    puts "About to run '#{cmd}'"

Keep files around with @no-clobber

Aruba clobbers all files in its working directory before each scenario. -Unless you tag it with @no-clobber

Making assertions about ANSI escapes with @ansi

Aruba strips away ANSI escapes from the stdout and stderr of spawned child processes by default. It's usually rather cumbersome to make assertions about coloured output. Still, there might be cases where you want to leave the ANSI escapes intact. Just tag your scenario with @ansi. Alternatively you can add your own Before hook that sets @aruba_keep_ansi = true.

Testing Ruby CLI programs without spawning a new Ruby process.

If your CLI program is written in Ruby you can speed up your suite of scenarios by running your CLI in the same process as Cucumber/Aruba itself. In order to be able to do this, the entry point for your CLI application must be a class that has a constructor with a particular signature and an execute! method:

class MyMain
  def initialize(argv, stdin=STDIN, stdout=STDOUT, stderr=STDERR, kernel=Kernel)
    @argv, @stdin, @stdout, @stderr, @kernel = argv, stdin, stdout, stderr, kernel

  def execute!
    # your code here, assign a value to exitstatus

Your bin/something executable would look something like the following:

require 'my_main'!

Then wire it all up in your features/support/env.rb file:

require 'aruba'
require 'aruba/in_process'

Aruba::InProcess.main_class = MyMain
Aruba.process = Aruba::InProcess

That's it! Everything will now run inside the same ruby process, making your suite a lot faster. Cucumber itself uses this approach to test itself, so check out the Cucumber source code for an example.


  • Very fast compared to spawning processes
  • You can use libraries like simplecov more easily, because there is only one "process" which adds data to simplecov's database


  • You might oversee some bugs: You might forget to require libraries in your "production" code, because you have required them in your testing code

JRuby Tips

Improve startup time by disabling JIT and forcing client JVM mode. This can be accomplished by adding

require 'aruba/jruby'

or setting a hook like this example:

Aruba.configure do |config|
  config.before_cmd do |cmd|
    set_env('JRUBY_OPTS', "-X-C #{ENV['JRUBY_OPTS']}") # disable JIT since these processes are so short lived
    set_env('JAVA_OPTS', "-d32 #{ENV['JAVA_OPTS']}") # force jRuby to use client JVM for faster startup times
end if RUBY_PLATFORM == 'java'

Note - no conflict resolution on the JAVA/JRuby environment options is done; only merging. For more complex settings please manually set the environment variables in the hook or externally.

A larger process timeout for java may be needed

Before do
  @aruba_timeout_seconds = RUBY_PLATFORM == 'java' ? 60 : 10

Refer to for other tips on startup time.


Sometimes your tests need existing files to work - e.g binary data files you cannot create programmatically. Since aruba >= 0.6.3 includes some basic support for fixtures. All you need to do is the following:

  1. Create a fixtures-directory
  2. Create fixture files in this directory

The expand_path-helper will expand % to the path of your fixtures directory:

# => /home/user/projects/my_project/fixtures/song.mp3


  1. Create fixtures directory
cd project

mkdir -p fixtures/
# or
mkdir -p test/fixtures/
# or
mkdir -p spec/fixtures/
# or
mkdir -p features/fixtures/
  1. Store song.mp3 in fixtures-directory
cp song.mp3 fixtures/
  1. Add fixture to vcs-repository - e.g. git, mercurial

  2. Create test

RSpec.describe 'My Feature' do
  describe '#read_music_file' do
    context 'when the file exists' do
      let(:path) { expand_path('%/song.mp3') }

      before :each do
        in_current_directory { FileUtils.cp path, 'file.mp3' }

      before :each do
        run 'my_command'

      it { expect(all_stdout).to include('Rate is 128 KB') }


Important - you need Pygments installed to use this feature.

Aruba can generate a HTML page for each scenario that contains:

  • The title of the scenario
  • The description from the scenario (You can use Markdown here)
  • The command(s) that were run
  • The output from those commands (in colour if the output uses ANSI escapes)
  • The files that were created (syntax highlighted in colour)

In addition to this, it creates an index.html file with links to all individual report files. Reporting is off by default, but you can enable it by defining the ARUBA_REPORT_DIR environment variable, giving it the value where reports should be written:

ARUBA_REPORT_DIR=doc cucumber features

This will use Aruba's built-in template by default (See the templates folder). If you want to use your own template you can override its location:

ARUBA_REPORT_TEMPLATES=templates ARUBA_REPORT_DIR=doc cucumber features

The templates directory must contain a main.erb and files.erb template. It can also contain other assets such as css, javascript and images. All of these files will be copied over to the report dir well.

Escaping Markdown

There are some edge cases where Gherkin and Markdown don't agree. Bullet lists using * is one example. The * is also an alias for step keywords in Gherkin. Markdown headers (the kind starting with a #) is another example. They are parsed as comments by Gherkin. To use either of these, just escape them with a backslash. So instead of writing:

Scenario: Make tea
  ## Making tea
  * Get a pot
  * And some hot water


You'd write:

Scenario: Make tea
  \## Making tea
  \* Get a pot
  \* And some hot water


This way Gherkin won't recognize these lines as special tokens, and the reporter will render them as Markdown. (The reporter strips away any leading the backslashes before handing it off to the Markdown parser).

Another option is to use alternative Markdown syntax and omit conflicts and escaping altogether:

Scenario: Make tea
  Making tea
  - Get a pot
  - And some hot water



Please see the


Copyright (c) 2010,2011,2012,2013,2014 Aslak Hellesøy, David Chelimsky and Mike Sassak. See LICENSE for details.


CLI Steps for Cucumber







No packages published


  • Ruby 81.2%
  • Gherkin 13.7%
  • CSS 3.1%
  • HTML 1.3%
  • Other 0.7%