Add rake task all:rubies which runs specs for ruby 1.8.7, 1.9.3 and 2…

….1.2

Rakefile

@@ -49,6 +49,22 @@ namespace :all do
     end
   end
 
+  desc 'Install gems and run tests on several Ruby versions'
+  task :rubies do
+    success = case
+    when system('which rvm')
+      run_for_all_rubies :rvm
+    when system('which rbenv') && `rbenv commands`.split("\n").include?('alias')
+      # rbenv currently works only with the alias plugin, as we do not want to
+      # specify Ruby versions down to their patch levels.
+      run_for_all_rubies :rbenv
+    else
+      fail 'Currently only RVM and rbenv (with alias plugin) are supported. Open Rakefile and add your Ruby version manager!'
+    end
+
+    fail "Tests failed" unless success
+  end
+
 end
 
 def for_each_directory_of(path, &block)
@@ -58,3 +74,35 @@ def for_each_directory_of(path, &block)
     block.call(directory)
   end
 end
+
+def run_for_all_rubies(version_manager)
+  %w[
+    1.8.7
+    1.9.3
+    2.1.2
+  ].all? do |ruby_version|
+    announce "Running bundle and specs for Ruby #{ruby_version}", 2
+
+    execute = case version_manager
+    when :rvm
+      "rvm #{ruby_version} do"
+    when :rbenv
+      ENV['RBENV_VERSION'] = ruby_version
+      'rbenv exec'
+    end
+
+    current_version = `#{execute} ruby -v`.match(/^ruby (\d\.\d\.\d)/)[1]
+    if current_version == ruby_version
+      puts "Currently active Ruby is #{current_version}"
+      system "#{execute} rake all:bundle all:spec"
+    else
+      fail "Failed to set Ruby #{ruby_version} (#{current_version} active!)"
+    end
+  end
+end
+
+def announce(text, level = 1)
+  space = "\n" * level
+  message = "# #{text}"
+  puts "\e[4;34m#{space + message}\e[0m" # blue underline
+end