devroom.io/content/posts/2014-04-15-testing-home-with-cucumber-and-aruba.md

+++
date = "2014-04-15"
title = "Testing $HOME with Cucumber and Aruba"
tags = ["programming", "cucumber", "aruba"]
description = "Cucumber and Aruba make it awesome to write acceptance tests for your command line programs. But how do you test your program interacting withfiles from a user's <code>$HOME</code> directory?"
slug = "testing-home-with-cucumber-and-aruba"
+++
[Cucumber][1] and [Aruba][2] are awesome tools to write acceptance tests for your command line application. The allow you to do things like this:

``` cucumber
Scenario: Exit with 0 when no examples are run
    Given a file named "a_no_examples_spec.rb" with:
        """ruby
        """
    When I run `rspec a_no_examples_spec.rb`
    Then the exit status should be 0
    And the output should contain "0 examples"
```

_This example was taken from rspec-core._

Aruba basically does three things for you:

 * Create and inspect files and directories
 * Run commands
 * Inspect output and exit status

## The problem

Now, if you are writing a CLI that interacts with a configuration file in the user's home directory, you'd write a cucumber like this:

``` cucumber
Scenario: use .my-app configuration
    Given a file named "~/.my-app" with:
        """
        awesome_enabled: true
        """
    When I run `my-app`
    Then the output should contain "AWESOME"
```

But how does your app and Aruba differentiate between this generated test file and your actual configration file in your home directory? It doens't.

## The answer

The solution is quite easy and elegant, in your `Before` set the `$HOME` environment variable to a custom location inside the `tmp/aruba` directory.

In `features/support/env.rb`:

``` ruby
Before do
  set_env 'HOME', File.expand_path(File.join(current_dir, 'home'))
  FileUtils.mkdir_p ENV['HOME']
end
```

This will set `$HOME` to `tmp/aruba/home` in the context of your cucumbers (and execute binary). `current_dir` automatically points to the right location for the aruba temporary directory.

[1]: https://github.com/cucumber/cucumber
[2]: https://github.com/cucumber/aruba