[#2281] Refactored the implementation of billable?.

lib/overhead_time_entry_activity_patch.rb

@@ -19,24 +19,36 @@ module OverheadTimeEntryActivityPatch
   module InstanceMethods
     # Is the Activity Billable, based on it's custom data?
     def billable?
-      if Setting['plugin_redmine_overhead'] && Setting['plugin_redmine_overhead']['custom_field']
+      if overhead_configured?
         billable_field = TimeEntryActivityCustomField.find_by_id(Setting['plugin_redmine_overhead']['custom_field'])
-
+        return field_equals_the_configured_billable_field?(billable_field)
-        if billable_field && field = self.custom_value_for(billable_field)
-          if billable_field.field_format == 'bool'
-            setting = (Setting['plugin_redmine_overhead']['billable_value'] == "true") ? true : false
-            activity_field = (field.value == "1") ? true : false
-            return activity_field == setting
-          else
-            return field.value == Setting['plugin_redmine_overhead']['billable_value']
-          end
-        else
-          return false
-        end
       else
         return false
       end
     end
+
+    private
+
+    def overhead_configured?
+      Setting['plugin_redmine_overhead'] && Setting['plugin_redmine_overhead']['custom_field']
+    end
+
+    # Checks if the field's value equals the  configured billable
+    # value.
+    def field_equals_the_configured_billable_field?(field=nil)
+      return false unless field
+      
+      custom_value = self.custom_value_for(field)
+      
+      if field.field_format == 'bool'
+        # Map string values to proper booleans
+        setting = (Setting['plugin_redmine_overhead']['billable_value'] == "true") ? true : false
+        activity_field = (custom_value.value == "1") ? true : false
+        return activity_field == setting
+      else
+        return custom_value.value == Setting['plugin_redmine_overhead']['billable_value']
+      end
+    end
   end    
 end