Running Your Test Cases in Isolation

The RSpec examples are generally run in a single ruby process. It dosen't matter until your code introduces some global variables, which would be polluted between examples. A common solution is to reset them in the after hook, but it breaks the DRY rule and would brings a lots of extra works. The best way is to run them in separated sub processes. This gem would help you to achieve this within a single method call.

Dependency

This gem depends on Rspec 2.0 and above. You should have it installed before using this gem.

Installation

sudo gem install rspec-isolation

Note: The installation would NOT automatically install the rspec 2.0.

Usage

Image a spec file exists:

$greeting = "Hello, world!"

describe "Test with global vars" do
  it "should be replaced with my name" do
    $greeting.gsub!(/\bworld\b/, "Kevin")
    $greeting.should == "Hello, Kevin!"
  end

  it "should be replaced with my hometown name" do
    $greeting.gsub!(/\bworld\b/, "Wuhan")
    $greeting.should == "Hello, Wuhan!"
  end
end

The $greeting is polluted in the first example and the second example would failed.

Now we require this gem:

require 'rspec/isolation'

Then you can choose one of the following ways to enable the isolation:

1. Using iso_it:

require 'rspec/isolation'
$greeting = "Hello, world!"

describe "Test with global vars" do
  iso_it "should be replaced with my name" do
    $greeting.gsub!(/\bworld\b/, "Kevin")
    $greeting.should == "Hello, Kevin!"
  end

  it "should be replaced with my hometown name" do
    $greeting.gsub!(/\bworld\b/, "Wuhan")
    $greeting.should == "Hello, Wuhan!"
  end
end

Now the first example would be run in a sub process.

2. Using run_in_isolation in before(:each) hook:

require 'rspec/isolation'
$greeting = "Hello, world!"

describe "Test with global vars" do
  before(:each) do
    run_in_isolation
  end
  it "should be replaced with my name" do
    $greeting.gsub!(/\bworld\b/, "Kevin")
    $greeting.should == "Hello, Kevin!"
  end

  it "should be replaced with my hometown name" do
    $greeting.gsub!(/\bworld\b/, "Wuhan")
    $greeting.should == "Hello, Wuhan!"
  end
end

Now all examples would be run in separated sub processes. Note: It won't work if you put run_in_isolation in a before(:all) hook.

Author

Kevin Fu, corntrace@gmail.com, @corntrace. If you like and use this gem, please feel free to give me any recommandation.