Make the non inferrable controller message a little friendlier. [Koz]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8749 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

actionpack/lib/action_controller/test_case.rb

@@ -3,9 +3,15 @@ require 'active_support/test_case'
 module ActionController
   class NonInferrableControllerError < ActionControllerError
     def initialize(name)
+      @name = name
       super "Unable to determine the controller to test from #{name}. " +
         "You'll need to specify it using 'tests YourController' in your " +
-        "test case definition"
+        "test case definition. This could mean that #{inferred_controller_name} does not exist " +
+        "or it contains syntax errors"
+    end
+
+    def inferred_controller_name
+      @name.sub(/Test$/, '')
     end
   end