diff --git a/enrol/lti/tests/local/ltiadvantage/entity/resource_link_test.php b/enrol/lti/tests/local/ltiadvantage/entity/resource_link_test.php
index 33963c63345..04f35d0b01c 100644
--- a/enrol/lti/tests/local/ltiadvantage/entity/resource_link_test.php
+++ b/enrol/lti/tests/local/ltiadvantage/entity/resource_link_test.php
@@ -229,15 +229,16 @@ class resource_link_test extends \advanced_testcase {
      * @covers ::add_user
      */
     public function test_add_user() {
+        global $CFG;
         $reslinkwithid = resource_link::create('res-link-id-123', 24, 44, 66, 33);
-        $user = $reslinkwithid->add_user(2, 'platform-user-id-123', 'en', 'Sydney', 'AU', 'Test university', '99');
+        $user = $reslinkwithid->add_user(2, 'platform-user-id-123', $CFG->lang, 'Sydney', 'AU', 'Test university', '99');
         $this->assertInstanceOf(user::class, $user);
         $this->assertEquals(33, $user->get_resourcelinkid());
 
         $reslinkwithoutid = resource_link::create('res-link-id-123', 24, 44);
         $this->expectException(\coding_exception::class);
         $this->expectExceptionMessage("Can't add user to a resource_link that hasn't first been saved");
-        $reslinkwithoutid->add_user(2, 'platform-user-id-123', 'en', 'Sydney', 'Australia', 'Test university', '99');
+        $reslinkwithoutid->add_user(2, 'platform-user-id-123', $CFG->lang, 'Sydney', 'Australia', 'Test university', '99');
     }
 
     /**
diff --git a/enrol/lti/tests/local/ltiadvantage/entity/user_test.php b/enrol/lti/tests/local/ltiadvantage/entity/user_test.php
index e456961fda2..ae594f9c8ce 100644
--- a/enrol/lti/tests/local/ltiadvantage/entity/user_test.php
+++ b/enrol/lti/tests/local/ltiadvantage/entity/user_test.php
@@ -65,6 +65,7 @@ class user_test extends \advanced_testcase {
      * @return array the data for testing.
      */
     public function create_data_provider(): array {
+        global $CFG;
         return [
             'Valid create, only required args provided' => [
                 'args' => [
@@ -72,7 +73,7 @@ class user_test extends \advanced_testcase {
                     'userid' => 2,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => '99'
                 ],
                 'expectations' => [
@@ -80,7 +81,7 @@ class user_test extends \advanced_testcase {
                     'resourceid' => 22,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => '99',
                     'city' => '',
                     'country' => '',
@@ -99,7 +100,7 @@ class user_test extends \advanced_testcase {
                     'userid' => 2,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => '99',
                     'city' => 'Melbourne',
                     'country' => 'AU',
@@ -115,7 +116,7 @@ class user_test extends \advanced_testcase {
                     'resourceid' => 22,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => '99',
                     'city' => 'Melbourne',
                     'country' => 'AU',
@@ -134,7 +135,7 @@ class user_test extends \advanced_testcase {
                     'userid' => 2,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => '99',
                     'city' => 'Melbourne',
                     'country' => 'AU',
@@ -151,7 +152,7 @@ class user_test extends \advanced_testcase {
                     'resourceid' => 22,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => '99',
                     'city' => 'Melbourne',
                     'country' => 'AU',
@@ -164,19 +165,19 @@ class user_test extends \advanced_testcase {
                     'id' => null
                 ]
             ],
-            'Invalid create, lang with bad value (fr not installed)' => [
+            'Invalid create, lang with bad value (vvvv not installed)' => [
                 'args' => [
                     'resourceid' => 22,
                     'userid' => 2,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'fr',
+                    'lang' => 'vvvv',
                     'timezone' => '99',
                 ],
                 'expectations' => [
                     'valid' => false,
                     'exception' => \coding_exception::class,
-                    'exceptionmessage' => "Invalid lang 'fr' provided."
+                    'exceptionmessage' => "Invalid lang 'vvvv' provided."
                 ]
             ],
             'Invalid create, timezone with bad value' => [
@@ -185,7 +186,7 @@ class user_test extends \advanced_testcase {
                     'userid' => 2,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => 'NOT/FOUND',
                 ],
                 'expectations' => [
@@ -200,7 +201,7 @@ class user_test extends \advanced_testcase {
                     'userid' => 2,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => '99',
                     'city' => '',
                     'country' => 'FFF',
@@ -217,7 +218,7 @@ class user_test extends \advanced_testcase {
                     'userid' => 2,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => '99',
                     'city' => '',
                     'country' => '',
@@ -272,6 +273,7 @@ class user_test extends \advanced_testcase {
      * @return array the data for testing.
      */
     public function create_from_resource_link_data_provider(): array {
+        global $CFG;
         return [
             'Valid creation, all args provided explicitly' => [
                 'args' => [
@@ -280,7 +282,7 @@ class user_test extends \advanced_testcase {
                     'userid' => 2,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => '99',
                     'city' => 'Melbourne',
                     'country' => 'AU',
@@ -295,7 +297,7 @@ class user_test extends \advanced_testcase {
                     'resourceid' => 22,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => '99',
                     'city' => 'Melbourne',
                     'country' => 'AU',
@@ -312,7 +314,7 @@ class user_test extends \advanced_testcase {
                     'userid' => 2,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => 'UTC'
                 ],
                 'expectations' => [
@@ -323,7 +325,7 @@ class user_test extends \advanced_testcase {
                     'resourceid' => 22,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => 'UTC',
                     'city' => '',
                     'country' => '',
@@ -340,7 +342,7 @@ class user_test extends \advanced_testcase {
                     'user' => 2,
                     'deploymentid' => 33,
                     'sourceid' => '',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => 'UTC'
                 ],
                 'expectations' => [
@@ -372,7 +374,7 @@ class user_test extends \advanced_testcase {
                     'userid' => 2,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => ''
                 ],
                 'expectations' => [
@@ -381,20 +383,20 @@ class user_test extends \advanced_testcase {
                     'exceptionmessage' => 'Invalid timezone value. Cannot be an empty string.'
                 ]
             ],
-            'Invalid creation, only required args provided, invalid lang (fr not installed)' => [
+            'Invalid creation, only required args provided, invalid lang (vvvv not installed)' => [
                 'args' => [
                     'resourcelinkid' => 11,
                     'resourceid' => 22,
                     'userid' => 2,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'fr',
+                    'lang' => 'vvvv',
                     'timezone' => 'UTC'
                 ],
                 'expectations' => [
                     'valid' => false,
                     'exception' => \coding_exception::class,
-                    'exceptionmessage' => "Invalid lang 'fr' provided."
+                    'exceptionmessage' => "Invalid lang 'vvvv' provided."
                 ]
             ],
             'Invalid creation, only required args provided, invalid timezone' => [
@@ -404,7 +406,7 @@ class user_test extends \advanced_testcase {
                     'userid' => 2,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => 'NOT/FOUND'
                 ],
                 'expectations' => [
@@ -420,7 +422,7 @@ class user_test extends \advanced_testcase {
                     'userid' => 2,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => '99',
                     'city' => 'Melbourne',
                     'country' => 'FFF',
@@ -440,7 +442,7 @@ class user_test extends \advanced_testcase {
                     'userid' => 2,
                     'deploymentid' => 33,
                     'sourceid' => 'user-id-123',
-                    'lang' => 'en',
+                    'lang' => $CFG->lang,
                     'timezone' => '99',
                     'city' => 'Melbourne',
                     'country' => 'AU',
@@ -462,13 +464,14 @@ class user_test extends \advanced_testcase {
      * @return user a user instance.
      */
     protected function create_test_user(): user {
+        global $CFG;
         $args = [
             'resourcelinkid' => 11,
             'resourceid' => 22,
             'userid' => 2,
             'deploymentid' => 33,
             'sourceid' => 'user-id-123',
-            'lang' => 'en',
+            'lang' => $CFG->lang,
             'timezone' => 'UTC'
         ];
         return user::create_from_resource_link(...array_values($args));
@@ -509,6 +512,7 @@ class user_test extends \advanced_testcase {
      * @return array the array of test data.
      */
     public function setters_getters_data_provider(): array {
+        global $CFG;
         return [
             'Testing set_resourcelinkid with valid id' => [
                 'methodname' => 'resourcelinkid',
@@ -641,7 +645,7 @@ class user_test extends \advanced_testcase {
             ],
             'Testing set_lang with valid lang code' => [
                 'methodname' => 'lang',
-                'arg' => 'en',
+                'arg' => $CFG->lang,
                 'expectations' => [
                     'valid' => true,
                 ]
diff --git a/enrol/lti/tests/local/ltiadvantage/repository/resource_link_repository_test.php b/enrol/lti/tests/local/ltiadvantage/repository/resource_link_repository_test.php
index 858a617d6d5..a9ff411f17c 100644
--- a/enrol/lti/tests/local/ltiadvantage/repository/resource_link_repository_test.php
+++ b/enrol/lti/tests/local/ltiadvantage/repository/resource_link_repository_test.php
@@ -197,6 +197,7 @@ class resource_link_repository_test extends \advanced_testcase {
      * @covers ::find_by_resource_and_user
      */
     public function test_find_by_resource_and_user() {
+        global $CFG;
         $this->resetAfterTest();
         $resourcelink = $this->generate_resource_link();
         $repository = new resource_link_repository();
@@ -214,7 +215,7 @@ class resource_link_repository_test extends \advanced_testcase {
         $user = $newreslink->add_user(
             $user1->id,
             'platform-user-id-123',
-            'en',
+            $CFG->lang,
             'Sydney',
             'AU',
             'Test university',
@@ -227,7 +228,7 @@ class resource_link_repository_test extends \advanced_testcase {
         $user2 = $newreslink3->add_user(
             $user2->id,
             'platform-user-id-777',
-            'en',
+            $CFG->lang,
             'Melbourne',
             'AU',
             'Test university',
@@ -255,6 +256,7 @@ class resource_link_repository_test extends \advanced_testcase {
      * @covers ::delete
      */
     public function test_delete() {
+        global $CFG;
         $this->resetAfterTest();
         $resourcelink = $this->generate_resource_link();
         $repository = new resource_link_repository();
@@ -265,7 +267,7 @@ class resource_link_repository_test extends \advanced_testcase {
         $user = $newreslink->add_user(
             2,
             'source-id-123',
-            'en',
+            $CFG->lang,
             'Perth',
             'AU',
             'An Example Institution',
@@ -293,6 +295,7 @@ class resource_link_repository_test extends \advanced_testcase {
      * @covers ::delete_by_resource
      */
     public function test_delete_by_resource() {
+        global $CFG;
         $this->resetAfterTest();
         $resourcelink = $this->generate_resource_link();
         $repository = new resource_link_repository();
@@ -302,7 +305,7 @@ class resource_link_repository_test extends \advanced_testcase {
         $user = $newreslink->add_user(
             2,
             'source-id-123',
-            'en',
+            $CFG->lang,
             'Perth',
             'AU',
             'An Example Institution',
@@ -337,6 +340,7 @@ class resource_link_repository_test extends \advanced_testcase {
      * @covers ::delete_by_deployment
      */
     public function test_delete_by_deployment() {
+        global $CFG;
         $this->resetAfterTest();
         $resourcelink = $this->generate_resource_link();
         $repository = new resource_link_repository();
@@ -347,7 +351,7 @@ class resource_link_repository_test extends \advanced_testcase {
         $user = $newreslink->add_user(
             2,
             'source-id-123',
-            'en',
+            $CFG->lang,
             'Perth',
             'AU',
             'An Example Institution',
diff --git a/enrol/lti/tests/local/ltiadvantage/repository/user_repository_test.php b/enrol/lti/tests/local/ltiadvantage/repository/user_repository_test.php
index c745a8a14f3..cd690379330 100644
--- a/enrol/lti/tests/local/ltiadvantage/repository/user_repository_test.php
+++ b/enrol/lti/tests/local/ltiadvantage/repository/user_repository_test.php
@@ -34,6 +34,7 @@ class user_repository_test extends \advanced_testcase {
      * @return user a user instance
      */
     protected function generate_user(int $mockresourceid = 1): user {
+        global $CFG;
         $registration = application_registration::create(
             'Test',
             'a2c94a2c94',
@@ -66,7 +67,7 @@ class user_repository_test extends \advanced_testcase {
         $ltiuser = $savedresourcelink->add_user(
             $user->id,
             'source-id-123',
-            'en',
+            $CFG->lang,
             'Perth',
             'AU',
             'An Example Institution',
@@ -215,6 +216,7 @@ class user_repository_test extends \advanced_testcase {
      * @covers ::save
      */
     public function test_save_stale_id() {
+        global $CFG;
         $this->resetAfterTest();
         $instructoruser = $this->getDataGenerator()->create_user();
         $userrepo = new user_repository();
@@ -223,7 +225,7 @@ class user_repository_test extends \advanced_testcase {
             $instructoruser->id,
             5,
             'source-id-123',
-            'en',
+            $CFG->lang,
             '99',
             '',
             '',
@@ -280,6 +282,7 @@ class user_repository_test extends \advanced_testcase {
      * @covers ::find_by_resource
      */
     public function test_find_by_resource() {
+        global $CFG;
         $this->resetAfterTest();
         $user = $this->generate_user();
         $userrepo = new user_repository();
@@ -291,7 +294,7 @@ class user_repository_test extends \advanced_testcase {
             $instructoruser->id,
             $saveduser->get_deploymentid(),
             'another-user-123',
-            'en',
+            $CFG->lang,
             '99',
             'Perth',
             'AU',
@@ -314,6 +317,7 @@ class user_repository_test extends \advanced_testcase {
      * @covers ::find_by_resource_link
      */
     public function test_find_by_resource_link() {
+        global $CFG;
         $this->resetAfterTest();
         $user = $this->generate_user();
         $user->set_resourcelinkid(33);
@@ -326,7 +330,7 @@ class user_repository_test extends \advanced_testcase {
             $instructoruser->id,
             $saveduser->get_deploymentid(),
             'another-user-123',
-            'en',
+            $CFG->lang,
             '99',
             'Perth',
             'AU',
@@ -390,6 +394,7 @@ class user_repository_test extends \advanced_testcase {
      * @covers ::delete_by_deployment
      */
     public function test_delete_by_deployment() {
+        global $CFG;
         $this->resetAfterTest();
         $user = $this->generate_user();
         $userrepo = new user_repository();
@@ -402,7 +407,7 @@ class user_repository_test extends \advanced_testcase {
             $instructoruser->id,
             $saveduser->get_deploymentid(),
             'another-user-123',
-            'en',
+            $CFG->lang,
             '99',
             'Perth',
             'AU',
@@ -415,7 +420,7 @@ class user_repository_test extends \advanced_testcase {
             $instructor2user->id,
             $saveduser->get_deploymentid() + 1,
             'another-user-678',
-            'en',
+            $CFG->lang,
             '99',
             'Melbourne',
             'AU',