Try to load lib before trying to activate the gem for testing

railties/test/abstract_unit.rb

@@ -27,8 +27,12 @@
 end
 
 def uses_gem(gem_name, test_name, version = '> 0')
-  gem gem_name.to_s, version
-  require gem_name.to_s
+  begin
+    require gem_name.to_s
+  rescue LoadError
+    gem gem_name.to_s, version
+    require gem_name.to_s
+  end
   yield
 rescue LoadError
   $stderr.puts "Skipping #{test_name} tests. `gem install #{gem_name}` and try again."