add more specs, fixed some errors

app/models/group.rb

@@ -230,12 +230,20 @@ class Group < Namespace
     ldap_group_links.first.try(:cn)
   end
 
+  def ldap_filter
+    ldap_group_links.first.try(:filter)
+  end
+
   def ldap_access
     ldap_group_links.first.try(:group_access)
   end
 
+  def ldap_cn_or_filter_present?
+    ldap_cn.present? || ldap_filter.present?
+  end
+
   def ldap_synced?
-    Gitlab.config.ldap.enabled && ldap_cn.present?
+    Gitlab.config.ldap.enabled && ldap_cn_or_filter_present?
   end
 
   def post_create_hook

app/models/ldap_group_link.rb

@@ -8,7 +8,7 @@ class LdapGroupLink < ActiveRecord::Base
   validates :cn, uniqueness: { scope: [:group_id, :provider] }, unless: :filter
   validates :filter, :group_access, :group_id, presence: true, unless: :cn
   validates :filter, uniqueness: { scope: [:group_id, :provider] }, unless: :cn
-  validates :filter, ldap_filter: true, if: :filter
+  validates :filter, ldap_filter: true, unless: :cn
   validates :group_access, inclusion: { in: Gitlab::Access.all_values }
   validates :provider, presence: true
 

spec/factories/groups.rb

@@ -27,20 +27,34 @@ FactoryGirl.define do
       end
     end
 
-    factory :group_with_ldap_group_link do
+    factory :group_with_ldap do
       transient do
         cn 'group1'
         group_access Gitlab::Access::GUEST
         provider 'ldapmain'
       end
 
-      after(:create) do |group, evaluator|
-        group.ldap_group_links << create(
-          :ldap_group_link,
-          cn: evaluator.cn,
-          group_access: evaluator.group_access,
-          provider: evaluator.provider
-        )
+      factory :group_with_ldap_group_link do
+        after(:create) do |group, evaluator|
+          group.ldap_group_links << create(
+              :ldap_group_link,
+              cn: evaluator.cn,
+              group_access: evaluator.group_access,
+              provider: evaluator.provider
+          )
+        end
+      end
+
+      factory :group_with_ldap_group_filter_link do
+        after(:create) do |group, evaluator|
+          group.ldap_group_links << create(
+              :ldap_group_link,
+              filter: '(a=b)',
+              cn: nil,
+              group_access: evaluator.group_access,
+              provider: evaluator.provider
+          )
+        end
       end
     end