Expose version and git revision

electric_sheep.gemspec

@@ -43,5 +43,6 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'mail', '~> 2.6', '>= 2.6.3'
   spec.add_dependency 'premailer', '~> 1.8', '>= 1.8.2'
   spec.add_dependency 'posix-spawn', '~> 0.3', '>= 0.3.9'
+  spec.add_dependency 'git_rev', '~> 0.1', '>= 0.1.0'
 
 end

lib/electric_sheep.rb

@@ -1,4 +1,5 @@
 require 'electric_sheep/version'
+require 'git_rev'
 require 'active_support'
 require 'active_support/core_ext'
 
@@ -23,15 +24,43 @@
 require 'electric_sheep/notifiers'
 
 module ElectricSheep
+
   class << self
+
     def template_path
       @_template_path ||= File.join(gem_path, 'templates')
     end
 
     def gem_path
       @_gem_path ||= File.expand_path(File.join(File.dirname(__FILE__), '..'))
     end
+
+    def version
+      VERSION
+    end
+
+    def git_revision
+      if @sha.nil?
+        if ENV['ELECTRIC_SHEEP_REVISION']
+          @sha = ENV['ELECTRIC_SHEEP_REVISION'][0, 7]
+        else
+          begin
+            @sha = GitRev::Sha.new.short
+          # Not a git repository
+          rescue
+            @sha = "-" * 7
+          end
+        end
+      end
+      @sha
+    end
+
+    def revision
+      [version, git_revision].join(" ")
+    end
+
   end
+
 end
 
 I18n.enforce_available_locales=false

spec/electric_sheep_spec.rb

@@ -10,4 +10,46 @@
     subject.template_path.must_equal "#{subject.gem_path}/templates"
   end
 
+  it 'provides the version' do
+    subject.version.must_equal ElectricSheep::VERSION
+  end
+
+  describe 'providing the revision hash' do
+
+    before do
+      subject.instance_variable_set(:@sha, nil)
+    end
+
+    after do
+      ENV['ELECTRIC_SHEEP_REVISION'] = nil
+    end
+
+    it 'uses the revision in cache' do
+      subject.instance_variable_set(:@sha, 'xxxxxxx')
+      subject.git_revision.must_equal 'xxxxxxx'
+    end
+
+    it 'gets the hash from an environment variable' do
+      ENV['ELECTRIC_SHEEP_REVISION'] = '0123456' + 'x' * 33
+      subject.git_revision.must_equal '0123456'
+    end
+
+    it 'get the hash from the git repository' do
+      GitRev::Sha.any_instance.expects(:short).returns 'fedcba9'
+      subject.git_revision.must_equal 'fedcba9'
+    end
+
+    it 'returns an unknown revision when unable to get it' do
+      GitRev::Sha.any_instance.expects(:short).raises 'An exception'
+      subject.git_revision.must_equal '-------'
+    end
+
+  end
+
+  it 'merges the version and git revision' do
+    subject.expects(:version).returns('0.0.0')
+    subject.expects(:git_revision).returns('0000000')
+    subject.revision.must_equal '0.0.0 0000000'
+  end
+
 end