diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 06871c6bc..2e89ebccc 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -79,6 +79,8 @@ test:unit:mysql:
     - rake db:seed
     - rake test:units
     - rake test:controllers
+    - ruby -I test/ test/integration/object_manager_test.rb
+    - ruby -I test/ test/integration/package_test.rb
     - rake db:drop
 
 test:unit:postgresql:
@@ -93,6 +95,8 @@ test:unit:postgresql:
     - rake db:seed
     - rake test:units
     - rake test:controllers
+    - ruby -I test/ test/integration/object_manager_test.rb
+    - ruby -I test/ test/integration/package_test.rb
     - rake db:drop
 
 test:integration:autowizard:
diff --git a/.pkgr.yml b/.pkgr.yml
index 8f87d0fc7..a4828c79f 100644
--- a/.pkgr.yml
+++ b/.pkgr.yml
@@ -18,7 +18,7 @@ targets:
     dependencies:
       - elasticsearch
       - nginx|apache2
-      - postgresql|mariadb-server|sqlite      
+      - postgresql|mariadb-server|sqlite
   ubuntu-16.04:
     dependencies:
       - elasticsearch
diff --git a/.travis.yml b/.travis.yml
index 2df15c507..e2ba0b4fc 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -41,6 +41,8 @@ script:
   - rake db:seed
   - rake test:units
   - rake test:controllers
+  - ruby -I test/ test/integration/object_manager_test.rb
+  - ruby -I test/ test/integration/package_test.rb
   - rake assets:precompile
   - rake db:drop
   - rake db:create
diff --git a/lib/sessions.rb b/lib/sessions.rb
index a78b29a2d..b191013a7 100644
--- a/lib/sessions.rb
+++ b/lib/sessions.rb
@@ -579,7 +579,7 @@ remove all session and spool messages
         next if !session_data
         next if !session_data[:user]
         next if !session_data[:user]['id']
-        user = User.lookup( id: session_data[:user]['id'] )
+        user = User.lookup(id: session_data[:user]['id'])
         next if !user
 
         # start client thread
@@ -590,7 +590,9 @@ remove all session and spool messages
           thread_client(client_id)
           @@client_threads[client_id] = nil
           log('debug', "close client (#{client_id}) thread")
-          ActiveRecord::Base.connection.close
+          if ActiveRecord::Base.connection.owner == Thread.current
+            ActiveRecord::Base.connection.close
+          end
         end
         sleep 0.5
       end
diff --git a/test/fixtures/seeds.rb b/test/fixtures/seeds.rb
index 4d788de1d..8ed902c03 100644
--- a/test/fixtures/seeds.rb
+++ b/test/fixtures/seeds.rb
@@ -20,5 +20,17 @@ email_address = EmailAddress.create_or_update(
 )
 Group.all.each do |group|
   group.email_address_id = email_address.id
-  group.save
+  group.save!
 end
+
+User.create_or_update(
+  login: 'admin@example.com',
+  firstname: 'Default',
+  lastname: 'Admin',
+  email: 'admin@example.com',
+  password: 'adminpw',
+  active: true,
+  roles: Role.where(name: %w(Admin)),
+  updated_by_id: 1,
+  created_by_id: 1,
+)
diff --git a/test/integration/clearbit_test.rb b/test/integration/clearbit_test.rb
index 0ca2dbc26..6e01e9ca0 100644
--- a/test/integration/clearbit_test.rb
+++ b/test/integration/clearbit_test.rb
@@ -2,6 +2,7 @@
 require 'integration_test_helper'
 
 class ClearbitTest < ActiveSupport::TestCase
+  self.use_transactional_tests = true
 
   # check
   test 'base' do
diff --git a/test/integration/facebook_test.rb b/test/integration/facebook_test.rb
index de647a283..769b9a523 100644
--- a/test/integration/facebook_test.rb
+++ b/test/integration/facebook_test.rb
@@ -2,6 +2,8 @@
 require 'integration_test_helper'
 
 class FacebookTest < ActiveSupport::TestCase
+  self.test_order = :sorted
+  self.use_transactional_tests = false
 
   # set system mode to done / to activate
   Setting.set('system_init_done', true)
diff --git a/test/unit/object_manager_test.rb b/test/integration/object_manager_test.rb
similarity index 99%
rename from test/unit/object_manager_test.rb
rename to test/integration/object_manager_test.rb
index 177be2eba..c6125a69f 100644
--- a/test/unit/object_manager_test.rb
+++ b/test/integration/object_manager_test.rb
@@ -2,6 +2,8 @@
 require 'test_helper'
 
 class ObjectManagerTest < ActiveSupport::TestCase
+  self.use_transactional_tests = false
+
   test 'a object manager' do
 
     list_objects = ObjectManager.list_objects
diff --git a/test/unit/package_test.rb b/test/integration/package_test.rb
similarity index 99%
rename from test/unit/package_test.rb
rename to test/integration/package_test.rb
index dfec3e3f2..1799e97cc 100644
--- a/test/unit/package_test.rb
+++ b/test/integration/package_test.rb
@@ -2,6 +2,8 @@
 require 'test_helper'
 
 class PackageTest < ActiveSupport::TestCase
+  self.use_transactional_tests = false
+
   test 'packages' do
     tests = [
 
diff --git a/test/integration/twitter_test.rb b/test/integration/twitter_test.rb
index 2675cdf87..c1d984f16 100644
--- a/test/integration/twitter_test.rb
+++ b/test/integration/twitter_test.rb
@@ -2,6 +2,8 @@
 require 'integration_test_helper'
 
 class TwitterTest < ActiveSupport::TestCase
+  self.test_order = :sorted
+  self.use_transactional_tests = false
 
   # set system mode to done / to activate
   Setting.set('system_init_done', true)
diff --git a/test/integration/user_device_controller_test.rb b/test/integration/user_device_controller_test.rb
index 25611dd26..a5788f44d 100644
--- a/test/integration/user_device_controller_test.rb
+++ b/test/integration/user_device_controller_test.rb
@@ -2,13 +2,16 @@
 require 'test_helper'
 
 class UserDeviceControllerTest < ActionDispatch::IntegrationTest
+  self.test_order = :sorted
+  self.use_transactional_tests = false
+
   setup do
 
     # set accept header
     @headers = { 'ACCEPT' => 'application/json', 'CONTENT_TYPE' => 'application/json' }
 
     # create agent
-    roles  = Role.where( name: %w(Admin Agent) )
+    roles  = Role.where(name: %w(Admin Agent))
     groups = Group.all
 
     UserInfo.current_user_id = 1
@@ -24,7 +27,7 @@ class UserDeviceControllerTest < ActionDispatch::IntegrationTest
     )
 
     # create agent
-    roles = Role.where( name: 'Agent' )
+    roles = Role.where(name: 'Agent')
     @agent = User.create_or_update(
       login: 'user-device-agent',
       firstname: 'UserDevice',
diff --git a/test/integration/zendesk_import_test.rb b/test/integration/zendesk_import_test.rb
index 820d53178..8d125fa7a 100644
--- a/test/integration/zendesk_import_test.rb
+++ b/test/integration/zendesk_import_test.rb
@@ -2,6 +2,8 @@
 require 'integration_test_helper'
 
 class ZendeskImportTest < ActiveSupport::TestCase
+  self.test_order = :sorted
+  self.use_transactional_tests = false
 
   if !ENV['IMPORT_ZENDESK_ENDPOINT']
     raise "ERROR: Need IMPORT_ZENDESK_ENDPOINT - hint IMPORT_ZENDESK_ENDPOINT='https://example.zendesk.com/api/v2'"
@@ -45,7 +47,7 @@ class ZendeskImportTest < ActiveSupport::TestCase
 
   # check count of imported items
   test 'check counts' do
-    assert_equal(143, User.count, 'users')
+    assert_equal(144, User.count, 'users')
     assert_equal(3, Group.count, 'groups')
     assert_equal(3, Role.count, 'roles')
     assert_equal(2, Organization.count, 'organizations')
@@ -69,7 +71,7 @@ class ZendeskImportTest < ActiveSupport::TestCase
 
     checks = [
       {
-        id:   4,
+        id:   5,
         data: {
           firstname:     'Bob',
           lastname:      'Smith',
@@ -83,7 +85,7 @@ class ZendeskImportTest < ActiveSupport::TestCase
         groups: [group_support],
       },
       {
-        id:   5,
+        id:   6,
         data: {
           firstname:     'Hansimerkur',
           lastname:      '',
@@ -96,7 +98,7 @@ class ZendeskImportTest < ActiveSupport::TestCase
         groups: [group_additional_group, group_support],
       },
       {
-        id:   6,
+        id:   7,
         data: {
           firstname: 'Bernd',
           lastname:  'Hofbecker',
@@ -108,7 +110,7 @@ class ZendeskImportTest < ActiveSupport::TestCase
         groups: [],
       },
       {
-        id:   7,
+        id:   8,
         data: {
           firstname: 'Zendesk',
           lastname:  '',
@@ -120,7 +122,7 @@ class ZendeskImportTest < ActiveSupport::TestCase
         groups: [],
       },
       {
-        id:   89,
+        id:   90,
         data: {
           firstname: 'Hans',
           lastname:  'Peter Wurst',
@@ -309,7 +311,7 @@ class ZendeskImportTest < ActiveSupport::TestCase
           group_id:                 3,
           priority_id:              3,
           owner_id:                 1,
-          customer_id:              6,
+          customer_id:              7,
           organization_id:          2,
           test_checkbox:            true,
           custom_integer:           999,
@@ -332,7 +334,7 @@ If you\'re reading this message in your email, click the ticket number link that
           group_id:                 3,
           priority_id:              1,
           owner_id:                 1,
-          customer_id:              7,
+          customer_id:              8,
           organization_id:          nil,
           test_checkbox:            false,
           custom_integer:           nil,
@@ -353,7 +355,7 @@ If you\'re reading this message in your email, click the ticket number link that
           group_id:                 3,
           priority_id:              2,
           owner_id:                 1,
-          customer_id:              91,
+          customer_id:              92,
           organization_id:          nil,
         },
       },
@@ -369,7 +371,7 @@ If you\'re reading this message in your email, click the ticket number link that
           group_id:                 1,
           priority_id:              2,
           owner_id:                 1,
-          customer_id:              143,
+          customer_id:              144,
           organization_id:          nil,
         },
       },
diff --git a/test/integration_test_helper.rb b/test/integration_test_helper.rb
index bd2991608..841df1ccc 100644
--- a/test/integration_test_helper.rb
+++ b/test/integration_test_helper.rb
@@ -4,8 +4,9 @@ require 'rails/test_help'
 require 'cache'
 
 class ActiveSupport::TestCase
-  # disable transactions
-  #self.use_transactional_tests = false
+
+  # disable transactions / to work with own database connections for each thread
+  self.use_transactional_tests = false
 
   ActiveRecord::Base.logger = Rails.logger.clone
   ActiveRecord::Base.logger.level = Logger::INFO
@@ -22,15 +23,12 @@ class ActiveSupport::TestCase
     # clear cache
     Cache.clear
 
+    # reload settings
+    Setting.reload
+
     # remove all session messages
     Sessions.cleanup
 
-    # remove background jobs
-    Delayed::Job.destroy_all
-    Trigger.destroy_all
-    ActivityStream.destroy_all
-    PostmasterFilter.destroy_all
-
     # set current user
     UserInfo.current_user_id = nil
   end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index c83c0aba7..d1064274c 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -7,10 +7,7 @@ require 'simplecov-rcov'
 require 'coveralls'
 Coveralls.wear!
 
-#ActiveSupport::TestCase.test_order = :sorted
-
 class ActiveSupport::TestCase
-  self.test_order = :sorted
 
   ActiveRecord::Base.logger = Rails.logger.clone
   ActiveRecord::Base.logger.level = Logger::INFO
@@ -27,9 +24,6 @@ class ActiveSupport::TestCase
   SimpleCov.start
   fixtures :all
 
-  # disable transactions
-  self.use_transactional_tests = false
-
   # clear cache
   Cache.clear
 
@@ -52,27 +46,12 @@ class ActiveSupport::TestCase
     # clear cache
     Cache.clear
 
+    # reload settings
+    Setting.reload
+
     # remove all session messages
     Sessions.cleanup
 
-    # remove background jobs
-    Delayed::Job.destroy_all
-    Trigger.destroy_all
-    ActivityStream.destroy_all
-    PostmasterFilter.destroy_all
-    Ticket.destroy_all
-    Taskbar.destroy_all
-    Sla.destroy_all
-    Calendar.destroy_all
-
-    # reset settings
-    Setting.all.pluck(:name).each do |name|
-      next if name == 'models_searchable' # skip setting
-      Setting.reset(name, false)
-    end
-    Setting.set('system_init_done', true)
-    Setting.reload
-
     # set current user
     UserInfo.current_user_id = nil
 
diff --git a/test/unit/session_enhanced_test.rb b/test/unit/session_enhanced_test.rb
index 3029c5589..680933deb 100644
--- a/test/unit/session_enhanced_test.rb
+++ b/test/unit/session_enhanced_test.rb
@@ -2,7 +2,7 @@
 require 'test_helper'
 
 class SessionEnhancedTest < ActiveSupport::TestCase
-  test 'a check clients and send messages' do
+  test 'check clients and send messages' do
 
     # create users
     roles  = Role.where(name: ['Agent'])
@@ -172,7 +172,8 @@ class SessionEnhancedTest < ActiveSupport::TestCase
     travel_back
   end
 
-  test 'b check client and backends' do
+  test 'check client and backends' do
+
     # create users
     roles        = Role.where(name: ['Agent'])
     groups       = Group.all
diff --git a/test/unit/user_test.rb b/test/unit/user_test.rb
index 7d0a7806a..e04984cf8 100644
--- a/test/unit/user_test.rb
+++ b/test/unit/user_test.rb
@@ -932,15 +932,9 @@ class UserTest < ActiveSupport::TestCase
   end
 
   test 'min admin permission check' do
-    # workaround:
-    # - We need to get rid of all admin users but can't delete them
-    #   because we have foreign keys pointing at them since the tests are not isolated yet :(
-    # - We can't just remove the roles since then our check would take place
-    # So we need to merge them with the User Nr 1 and destroy them afterwards
-    User.with_permissions('admin').each do |user|
-      Models.merge('User', 1, user.id)
-      user.destroy!
-    end
+
+    # delete inital admin
+    User.find_by(login: 'admin@example.com').destroy
 
     # store current admin count
     admin_count_inital = User.with_permissions('admin').count
diff --git a/test/unit/user_validate_agent_limit_test.rb b/test/unit/user_validate_agent_limit_test.rb
index 855b640ce..2fbfa936c 100644
--- a/test/unit/user_validate_agent_limit_test.rb
+++ b/test/unit/user_validate_agent_limit_test.rb
@@ -79,7 +79,7 @@ class UserValidateAgentLimit < ActiveSupport::TestCase
       permissions: Permission.where(name: 'ticket.agent'),
       active: false,
     )
-    user3.roles =  [role_agent_limit]
+    user3.roles = [role_agent_limit]
     user3.active = true
     user3.save!
 
@@ -90,6 +90,17 @@ class UserValidateAgentLimit < ActiveSupport::TestCase
 
     assert_equal(User.with_permissions('ticket.agent').count, agent_max)
 
+    # set roles of agent again
+    role_admin = Role.lookup(name: 'Admin')
+    user2.roles = [role_agent, role_admin]
+    user2.save!
+
+    user2.role_ids = [role_admin.id, role_agent_limit.id]
+    user2.save!
+
+    user2.role_ids = [role_admin.id.to_s, role_agent_limit.id.to_s]
+    user2.save!
+
     user1.destroy!
     user2.destroy!
     user3.destroy!