diff --git a/test/test_helper.rb b/test/test_helper.rb
index 11bd52c..20ef4b1 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -278,9 +278,12 @@ module Redmine
   end
 
   class HelperTest < ActionView::TestCase
+    include Redmine::I18n
+
     def setup
       super
       User.current = nil
+      ::I18n.locale = 'en'
     end
   end
 
diff --git a/test/unit/helpers/activities_helper_test.rb b/test/unit/helpers/activities_helper_test.rb
index a7df3c6..6c6c0c8 100644
--- a/test/unit/helpers/activities_helper_test.rb
+++ b/test/unit/helpers/activities_helper_test.rb
@@ -19,7 +19,6 @@ require File.expand_path('../../../test_helper', __FILE__)
 
 class ActivitiesHelperTest < Redmine::HelperTest
   include ActivitiesHelper
-  include Redmine::I18n
 
   class MockEvent
     attr_reader :event_datetime, :event_group, :name
diff --git a/test/unit/helpers/application_helper_test.rb b/test/unit/helpers/application_helper_test.rb
index 299488a..e6530e5 100644
--- a/test/unit/helpers/application_helper_test.rb
+++ b/test/unit/helpers/application_helper_test.rb
@@ -20,7 +20,6 @@
 require File.expand_path('../../../test_helper', __FILE__)
 
 class ApplicationHelperTest < Redmine::HelperTest
-  include Redmine::I18n
   include ERB::Util
   include Rails.application.routes.url_helpers
 
diff --git a/test/unit/helpers/custom_fields_helper_test.rb b/test/unit/helpers/custom_fields_helper_test.rb
index 7e352a9..21a9a12 100644
--- a/test/unit/helpers/custom_fields_helper_test.rb
+++ b/test/unit/helpers/custom_fields_helper_test.rb
@@ -20,7 +20,6 @@ require File.expand_path('../../../test_helper', __FILE__)
 class CustomFieldsHelperTest < Redmine::HelperTest
   include ApplicationHelper
   include CustomFieldsHelper
-  include Redmine::I18n
   include ERB::Util
 
   def test_format_boolean_value
diff --git a/test/unit/helpers/groups_helper_test.rb b/test/unit/helpers/groups_helper_test.rb
index 3f10628..1f30dcf 100644
--- a/test/unit/helpers/groups_helper_test.rb
+++ b/test/unit/helpers/groups_helper_test.rb
@@ -18,7 +18,6 @@
 require File.expand_path('../../../test_helper', __FILE__)
 
 class GroupsHelperTest < Redmine::HelperTest
-  include Redmine::I18n
   include ERB::Util
   include GroupsHelper
   include Rails.application.routes.url_helpers
diff --git a/test/unit/helpers/issues_helper_test.rb b/test/unit/helpers/issues_helper_test.rb
index d618470..e255d1e 100644
--- a/test/unit/helpers/issues_helper_test.rb
+++ b/test/unit/helpers/issues_helper_test.rb
@@ -18,7 +18,6 @@
 require File.expand_path('../../../test_helper', __FILE__)
 
 class IssuesHelperTest < Redmine::HelperTest
-  include Redmine::I18n
   include IssuesHelper
   include CustomFieldsHelper
   include ERB::Util
@@ -35,11 +34,6 @@ class IssuesHelperTest < Redmine::HelperTest
            :attachments,
            :versions
 
-  def setup
-    super
-    set_language_if_valid('en')
-  end
-
   def test_issue_heading
     assert_equal "Bug #1", issue_heading(Issue.find(1))
   end
diff --git a/test/unit/helpers/members_helper_test.rb b/test/unit/helpers/members_helper_test.rb
index 0cda5d6..ad3e1cc 100644
--- a/test/unit/helpers/members_helper_test.rb
+++ b/test/unit/helpers/members_helper_test.rb
@@ -18,7 +18,6 @@
 require File.expand_path('../../../test_helper', __FILE__)
 
 class MembersHelperTest < Redmine::HelperTest
-  include Redmine::I18n
   include ERB::Util
   include MembersHelper
   include Rails.application.routes.url_helpers
diff --git a/test/unit/helpers/my_helper_test.rb b/test/unit/helpers/my_helper_test.rb
index 0448741..d79525d 100644
--- a/test/unit/helpers/my_helper_test.rb
+++ b/test/unit/helpers/my_helper_test.rb
@@ -18,7 +18,6 @@
 require File.expand_path('../../../test_helper', __FILE__)
 
 class MyHelperTest < Redmine::HelperTest
-  include Redmine::I18n
   include ERB::Util
   include MyHelper
 
diff --git a/test/unit/helpers/projects_helper_test.rb b/test/unit/helpers/projects_helper_test.rb
index 2e87414..fc6afe6 100644
--- a/test/unit/helpers/projects_helper_test.rb
+++ b/test/unit/helpers/projects_helper_test.rb
@@ -20,7 +20,6 @@ require File.expand_path('../../../test_helper', __FILE__)
 class ProjectsHelperTest < Redmine::HelperTest
   include ApplicationHelper
   include ProjectsHelper
-  include Redmine::I18n
   include ERB::Util
   include Rails.application.routes.url_helpers
 
@@ -33,11 +32,6 @@ class ProjectsHelperTest < Redmine::HelperTest
            :groups_users,
            :enabled_modules
 
-  def setup
-    super
-    set_language_if_valid('en')
-  end
-
   def test_link_to_version_within_project
     @project = Project.find(2)
     User.current = User.find(1)
diff --git a/test/unit/helpers/queries_helper_test.rb b/test/unit/helpers/queries_helper_test.rb
index 6b10d50..12f00ce 100644
--- a/test/unit/helpers/queries_helper_test.rb
+++ b/test/unit/helpers/queries_helper_test.rb
@@ -19,7 +19,6 @@ require File.expand_path('../../../test_helper', __FILE__)
 
 class QueriesHelperTest < Redmine::HelperTest
   include QueriesHelper
-  include Redmine::I18n
 
   fixtures :projects, :enabled_modules, :users, :members,
            :member_roles, :roles, :trackers, :issue_statuses,
diff --git a/test/unit/helpers/search_helper_test.rb b/test/unit/helpers/search_helper_test.rb
index 6e1b1ac..888f4d3 100644
--- a/test/unit/helpers/search_helper_test.rb
+++ b/test/unit/helpers/search_helper_test.rb
@@ -21,7 +21,6 @@ require File.expand_path('../../../test_helper', __FILE__)
 
 class SearchHelperTest < Redmine::HelperTest
   include SearchHelper
-  include Redmine::I18n
   include ERB::Util
 
   def test_highlight_single_token
diff --git a/test/unit/helpers/settings_helper_test.rb b/test/unit/helpers/settings_helper_test.rb
index 42dc7a5..10649d2 100644
--- a/test/unit/helpers/settings_helper_test.rb
+++ b/test/unit/helpers/settings_helper_test.rb
@@ -19,7 +19,6 @@ require File.expand_path('../../../test_helper', __FILE__)
 
 class SettingsHelperTest < Redmine::HelperTest
   include SettingsHelper
-  include Redmine::I18n
   include ERB::Util
 
   def test_date_format_setting_options_should_include_human_readable_format
diff --git a/test/unit/helpers/sort_helper_test.rb b/test/unit/helpers/sort_helper_test.rb
index 3aedcca..33657dc 100644
--- a/test/unit/helpers/sort_helper_test.rb
+++ b/test/unit/helpers/sort_helper_test.rb
@@ -19,7 +19,6 @@ require File.expand_path('../../../test_helper', __FILE__)
 
 class SortHelperTest < Redmine::HelperTest
   include SortHelper
-  include Redmine::I18n
   include ERB::Util
 
   def setup
diff --git a/test/unit/helpers/timelog_helper_test.rb b/test/unit/helpers/timelog_helper_test.rb
index ad04b99..61b9219 100644
--- a/test/unit/helpers/timelog_helper_test.rb
+++ b/test/unit/helpers/timelog_helper_test.rb
@@ -19,7 +19,6 @@ require File.expand_path('../../../test_helper', __FILE__)
 
 class TimelogHelperTest < Redmine::HelperTest
   include TimelogHelper
-  include Redmine::I18n
   include ActionView::Helpers::TextHelper
   include ActionView::Helpers::DateHelper
   include ERB::Util
diff --git a/test/unit/helpers/watchers_helper_test.rb b/test/unit/helpers/watchers_helper_test.rb
index 2dccfa1..47c7d07 100644
--- a/test/unit/helpers/watchers_helper_test.rb
+++ b/test/unit/helpers/watchers_helper_test.rb
@@ -19,16 +19,10 @@ require File.expand_path('../../../test_helper', __FILE__)
 
 class WatchersHelperTest < Redmine::HelperTest
   include WatchersHelper
-  include Redmine::I18n
   include Rails.application.routes.url_helpers
 
   fixtures :users, :issues
 
-  def setup
-    super
-    set_language_if_valid('en')
-  end
-
   test '#watcher_link with a non-watched object' do
     expected = link_to(
       "Watch",