diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 05f0a2a6..b846839d 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -16,7 +16,7 @@ def info
 
   # Find the user that owns the access token
   def current_resource_owner
-    User.find(doorkeeper_token.resource_owner_id) if doorkeeper_token
+    User.find(doorkeeper_token.resource_owner_id) if doorkeeper_token && doorkeeper_token.resource_owner_id
   end
 
   def current_user
diff --git a/test/controllers/oauth_controller_test.rb b/test/controllers/oauth_controller_test.rb
new file mode 100644
index 00000000..6b3606fb
--- /dev/null
+++ b/test/controllers/oauth_controller_test.rb
@@ -0,0 +1,31 @@
+require 'test_helper'
+require 'authorization_helper'
+
+class OauthControllerTest < ActionDispatch::IntegrationTest
+  include AuthorizationHelper
+  include Devise::Test::IntegrationHelpers
+
+  setup do
+    if ENV['ENABLE_AUTHENTICATION'].present?
+
+    end
+    @pia = FactoryBot.create(:pia)
+    @admin = FactoryBot.create(:user_admin, identifier: "admin")
+    @doorkeeper_token = doorkeeper_token
+    @auth = FactoryBot.create(:access_token)
+    @auth_tokens = nil
+  end
+
+  test "should not access to pia because is not logged" do
+    get pias_url
+    assert_response :unauthorized
+  end
+
+  test "admin authentification and get pias" do
+    @auth_tokens = auth_tokens_for_user(@admin, @auth)
+    @doorkeeper_token = @auth_tokens['access_token']
+
+    get pias_url, headers: { 'Authorization' => "Bearer #{@doorkeeper_token}" }, as: :json
+    assert_response :success
+  end
+end
diff --git a/test/controllers/users_controller_test.rb b/test/controllers/users_controller_test.rb
index 95f2f132..acb70ed0 100644
--- a/test/controllers/users_controller_test.rb
+++ b/test/controllers/users_controller_test.rb
@@ -46,18 +46,6 @@ class UsersControllerTest < ActionDispatch::IntegrationTest
     end
   end
 
-  # TODO
-  test "test delete the only one admin" do
-    if ENV['ENABLE_AUTHENTICATION'].present?
-      user_to_delete = FactoryBot.create(:user, identifier: "technical")
-      delete user_url(user_to_delete), headers: {
-        "Authorization": "Bearer #{@auth_tokens['access_token']}"
-      }
-
-      # should not return a error
-    end
-  end
-
   test "test process to unlock user and set password" do
     # create a user locked by default
     new_user = FactoryBot.create(:user)
diff --git a/test/factories/users.rb b/test/factories/users.rb
index 28d9c222..d17bd046 100644
--- a/test/factories/users.rb
+++ b/test/factories/users.rb
@@ -6,7 +6,7 @@
 
     firstname { 'user' }
     lastname { 'nothing' }
-    password { [*'0'..'9', *'a'..'z', *'A'..'Z', *'!'..'?'].sample(16).join }
+    password { [*'0'..'9', *'a'..'z', *'A'..'Z', *'!'..'?'].sample(16).join('-') }
     password_confirmation { password }
     is_user { true }
     email { "user+#{identifier ? identifier : 'default'}@test.com" }