Test Dependency Task

test.rake

namespace :test do
  desc "Ensures there are no dependencies between test classes."
  task :each => %w(each:functional each:unit each:integration)

  namespace :each do
    def each_test(tests)
      # This is where the magic happens
      ENV['TESTOPTS'] = '--verbose=progress' unless ENV['TESTOPTS']
      tests.each do |path|
        puts "\n#{path}"
        ENV['TEST'] = path
        Rake::Task['test'].execute
      end
    end

    desc "Run functional test classes independently."
    task :functional do
      each_test Dir["test/functional/**/*_test.rb"]
    end

    desc "Run unit test classes independently."
    task :unit do
      each_test Dir["test/unit/**/*_test.rb"]
    end

    desc "Run integration test classes independently."
    task :integration do
      each_test Dir["test/integration/**/*_test.rb"]
    end
  end
end

Do your test classes depend on one another? Want to be sure they don't? Here's a handy dandy rake task to help.

The idea is to iterate over all test classes and run it in isolation from others. I found in the project I'm working on that some tests had side effects which caused others to fail when run in isolation, but work when running the full suite. It takes a while to run; add it to your CI suite for extra juiciness.

Usage:

rake test:each # Ensures there are no dependencies between test classes.
rake test:each:functional # Run functional test classes independently.
rake test:each:integration # Run integration test classes independently.
rake test:each:unit # Run unit test classes independently.