Group all test related gems in :test group and do not require them automatically

Gemfile

@@ -1,10 +1,13 @@
 source "http://rubygems.org"
 
 gem "rails", "~> 3.0.0"
-gem "mocha"
 
-if RUBY_VERSION < "1.9"
-  gem "ruby-debug"
-else
-  gem "test-unit"
+group :test do
+  gem "mocha", :require => false
+
+  if RUBY_VERSION < "1.9"
+    gem "ruby-debug", :require => false
+  else
+    gem "test-unit", :require => false
+  end
 end

Gemfile.lock

@@ -28,20 +28,20 @@ GEM
       activemodel (= 3.0.3)
       activesupport (= 3.0.3)
     activesupport (3.0.3)
-    arel (2.0.4)
+    arel (2.0.6)
     builder (2.1.2)
     columnize (0.3.2)
     erubis (2.6.6)
       abstract (>= 1.0.0)
-    i18n (0.4.2)
+    i18n (0.5.0)
     linecache (0.43)
-    mail (2.2.10)
+    mail (2.2.12)
       activesupport (>= 2.3.6)
-      i18n (~> 0.4.1)
+      i18n (>= 0.4.0)
       mime-types (~> 1.16)
       treetop (~> 1.4.8)
     mime-types (1.16)
-    mocha (0.9.9)
+    mocha (0.9.10)
       rake
     polyglot (0.3.1)
     rack (1.2.1)