Fix enable_net_connection! when Connection is first used

ActiveResource::HttpMock.enable_net_connection! was ignored on
the first call to ActiveResource::Connection#http.

Author: khuston

lib/active_resource/http_mock.rb

@@ -375,11 +375,11 @@ def http_stub
         end
 
         def unstub_http?
-          HttpMock.net_connection_enabled? && defined?(@http) && @http.kind_of?(HttpMock)
+          HttpMock.net_connection_enabled? && (!defined?(@http) || @http.kind_of?(HttpMock))
         end
 
         def stub_http?
-          HttpMock.net_connection_disabled? && defined?(@http) && @http.kind_of?(Net::HTTP)
+          HttpMock.net_connection_disabled? && (!defined?(@http) || @http.kind_of?(Net::HTTP))
         end
       end
   end

test/cases/connection_test.rb

@@ -312,6 +312,13 @@ def test_enable_net_connection
     end
   end
 
+  def test_enable_net_connection_first_time
+    keep_net_connection_status do
+      ActiveResource::HttpMock.enable_net_connection!
+      assert @conn.send(:http).kind_of?(Net::HTTP)
+    end
+  end
+
   def test_disable_net_connection
     keep_net_connection_status do
       ActiveResource::HttpMock.enable_net_connection!