only define gem packaging tasks if rubygems is already loaded

Rakefile

@@ -5,6 +5,11 @@ require 'fileutils'
 task :default => :test
 task :spec => :test
 
+def source_version
+  line = File.read('lib/sinatra/base.rb')[/^\s*VERSION = .*/]
+  line.match(/.*VERSION = '(.*)'/)[1]
+end
+
 # SPECS ===============================================================
 
 Rake::TestTask.new(:test) do |t|
@@ -12,8 +17,43 @@ Rake::TestTask.new(:test) do |t|
   t.ruby_opts = ['-rubygems -I.'] if defined? Gem
 end
 
+# Rcov ================================================================
+namespace :test do
+  desc 'Mesures test coverage'
+  task :coverage do
+    rm_f "coverage"
+    rcov = "rcov --text-summary --test-unit-only -Ilib"
+    system("#{rcov} --no-html --no-color test/*_test.rb")
+  end
+end
+
+# Website =============================================================
+# Building docs requires HAML and the hanna gem:
+#   gem install mislav-hanna --source=http://gems.github.com
+
+desc 'Generate RDoc under doc/api'
+task 'doc'     => ['doc:api']
+
+task 'doc:api' => ['doc/api/index.html']
+
+file 'doc/api/index.html' => FileList['lib/**/*.rb','README.rdoc'] do |f|
+  rb_files = f.prerequisites
+  sh((<<-end).gsub(/\s+/, ' '))
+    hanna --charset utf8 \
+          --fmt html \
+          --inline-source \
+          --line-numbers \
+          --main README.rdoc \
+          --op doc/api \
+          --title 'Sinatra API Documentation' \
+          #{rb_files.join(' ')}
+  end
+end
+CLEAN.include 'doc/api'
+
 # PACKAGING ============================================================
 
+if defined?(Gem)
   # Load the gemspec using the same limitations as github
   def spec
     require 'rubygems' unless defined? Gem::Specification
@@ -49,37 +89,6 @@ file package('.tar.gz') => %w[pkg/] + spec.files do |f|
     SH
   end
 
-# Website ============================================================
-# Building docs requires HAML and the hanna gem:
-#   gem install mislav-hanna --source=http://gems.github.com
-
-task 'doc'     => ['doc:api']
-
-desc 'Generate Hanna RDoc under doc/api'
-task 'doc:api' => ['doc/api/index.html']
-
-file 'doc/api/index.html' => FileList['lib/**/*.rb','README.rdoc'] do |f|
-  rb_files = f.prerequisites
-  sh((<<-end).gsub(/\s+/, ' '))
-    hanna --charset utf8 \
-          --fmt html \
-          --inline-source \
-          --line-numbers \
-          --main README.rdoc \
-          --op doc/api \
-          --title 'Sinatra API Documentation' \
-          #{rb_files.join(' ')}
-  end
-end
-CLEAN.include 'doc/api'
-
-# Gemspec Helpers ====================================================
-
-def source_version
-  line = File.read('lib/sinatra/base.rb')[/^\s*VERSION = .*/]
-  line.match(/.*VERSION = '(.*)'/)[1]
-end
-
   task 'sinatra.gemspec' => FileList['{lib,test,compat}/**','Rakefile','CHANGES','*.rdoc'] do |f|
     # read spec file and split out manifest section
     spec = File.read(f.name)
@@ -101,13 +110,4 @@ task 'sinatra.gemspec' => FileList['{lib,test,compat}/**','Rakefile','CHANGES','
     File.open(f.name, 'w') { |io| io.write(spec) }
     puts "updated #{f.name}"
   end
-
-# Rcov ==============================================================
-namespace :test do
-  desc 'Mesures test coverage'
-  task :coverage do
-    rm_f "coverage"
-    rcov = "rcov --text-summary --test-unit-only -Ilib"
-    system("#{rcov} --no-html --no-color test/*_test.rb")
-  end
 end