raise InvalidAttribute if Base#count is called with a custom attribute

lib/sugarcrm/base.rb

@@ -56,6 +56,7 @@ def connection
     # note: the REST API has a bug where passing custom attributes in the options will result in the 
     # options being ignored and '0' being returned, regardless of the existence of records satisfying the options
     def count(options={})
+      raise InvalidAttribute, 'Conditions on custom attributes are not supported due to REST API bug' if contains_custom_attribute(options[:conditions])
       query = query_from_options(options)
       connection.get_entries_count(self._module.name, query, options)['result_count'].to_i
     end
@@ -261,6 +262,15 @@ def is_a?(klass)
   alias :=== :is_a?
 
   private
+  # returns true if the hash contains a custom attribute created in Studio (and whose name therefore ends in '_c')
+  def self.contains_custom_attribute(attributes)
+    attributes ||= {}
+    attributes.each_key{|k|
+      return true if k.to_s =~ /_c$/
+    }
+    false
+  end
+
   def superclasses
     return @superclasses if @superclasses
     @superclasses = [self.class]

test/test_sugarcrm.rb

@@ -11,15 +11,24 @@ class TestSugarCRM < ActiveSupport::TestCase
       assert first_account.id != new_account.id
     end
 
-    should "implement self.class.count" do
+    should "implement self.count" do
       nb_accounts = SugarCRM::Account.count
       assert nb_accounts > 0
-      nb_inc_accounts = SugarCRM::Account.count(:conditions => {:name => "LIKE '%Inc'"})
+      nb_inc_accounts = nil
+      assert_nothing_raised do
+        nb_inc_accounts = SugarCRM::Account.count(:conditions => {:name => "LIKE '%Inc'"})
+      end
       nb_inc_accounts_size = SugarCRM::Account.all(:conditions => {:name => "LIKE '%Inc'"}).size
       assert nb_inc_accounts > 0
       assert nb_inc_accounts < nb_accounts
       assert_equal nb_inc_accounts_size, nb_inc_accounts
     end
+
+    should "raise InvalidAttribute if self.count is called with a custom attribute" do
+      assert_raise SugarCRM::InvalidAttribute do
+        SugarCRM::Account.count(:conditions => {:custom_attribute_c => "value"})
+      end
+    end
   end
 
   context "A SugarCRM::Base instance" do