Fix exception on not recognized shortcut

Author: codesnik

lib/calculate-all.rb

@@ -97,7 +97,7 @@ def decode_expression_shortcut(shortcut, group_values = [])
       when /^(\w+)_minimum$/, /^minimum_(\w+)$/
         "MIN(#{$1})"
       else
-        raise ArgumentError, "Can't recognize expression shortcut #{key}"
+        raise ArgumentError, "Can't recognize expression shortcut #{shortcut}"
       end
     end
   end

test/calculate_all_test.rb

@@ -90,6 +90,12 @@ def test_no_args
     end
   end
 
+  def test_unknown_shortcut
+    assert_raises ArgumentError do
+      Order.all.calculate_all(:foo)
+    end
+  end
+
   def test_model_and_no_data
     assert_nil(Order.calculate_all("sum(cents)"))
   end