Only allow to configure columns as summable, that can be summed

no more "sum that subject and the versions!"

app/helpers/settings_helper.rb

@@ -149,14 +149,18 @@ module SettingsHelper
 
   def build_settings_matrix_body(settings, choices)
     choices.map { |choice|
-      text, value = (choice.is_a?(Array)) ? choice : [choice, choice]
+      value = choice[:value]
+      caption = choice[:caption] || value.to_s
+      exceptions = Array(choice[:except]).compact
       content_tag(:tr, class: 'form--matrix-row') do
-        content_tag(:td, text, class: 'form--matrix-cell') +
+        content_tag(:td, caption, class: 'form--matrix-cell') +
           settings.map { |setting|
             content_tag(:td, class: 'form--matrix-checkbox-cell') do
-              styled_check_box_tag("settings[#{setting}][]", value,
-                                   Setting.send(setting).include?(value),
-                                   id: "#{setting}_#{value}")
+              unless exceptions.include?(setting)
+                styled_check_box_tag("settings[#{setting}][]", value,
+                                     Setting.send(setting).include?(value),
+                                     id: "#{setting}_#{value}")
+              end
             end
           }.join.html_safe
       end

app/views/settings/_work_packages.html.erb

@@ -36,8 +36,15 @@ See doc/COPYRIGHT.rdoc for more details.
     <div class="form--field"><%= setting_text_field :work_packages_export_limit, :size => 6 %></div>
   </section>
   <fieldset class="form--fieldset"><legend class="form--fieldset-legend"><%= l(:setting_column_options) %></legend>
+    <%
+       column_choices = Query.new.available_columns.map { |column|
+         choice = { caption: column.caption, value: column.name.to_s }
+         choice[:except] = :work_package_list_summable_columns unless column.summable?
+         choice
+       }
+    %>
     <%= settings_matrix([:work_package_list_default_columns, :work_package_list_summable_columns],
-  Query.new.available_columns.collect {|c| [c.caption, c.name.to_s]}, :label_choices => :setting_work_package_properties) %>
+                        column_choices, :label_choices => :setting_work_package_properties) %>
   </fieldset>
   <%= styled_button_tag l(:button_save), class: '-highlight -with-icon icon-yes' %>
 <% end %>

spec/helpers/settings_helper_spec.rb

@@ -87,9 +87,25 @@ describe SettingsHelper, type: :helper do
     end
 
     subject(:output) {
-      helper.settings_matrix [:field_a, :field_b], [
-        ['Popsickle', '1'], ['Jello', '2'], ['Ice Cream', '3'], 'Quarkspeise'
+      settings = [:field_a, :field_b]
+      choices = [
+        {
+          caption: 'Popsickle',
+          value: '1'
+        },
+        {
+          caption: 'Jello',
+          value: '2'
+        },
+        {
+          caption: 'Ice Cream',
+          value: '3'
+        },
+        {
+          value: 'Quarkspeise'
+        }
       ]
+      helper.settings_matrix settings, choices
     }
 
     it_behaves_like 'not wrapped in container'