diff --git a/docs/apis/subsystems/external/testing.md b/docs/apis/subsystems/external/testing.md
index 02390fbc7..c218cf102 100644
--- a/docs/apis/subsystems/external/testing.md
+++ b/docs/apis/subsystems/external/testing.md
@@ -20,10 +20,18 @@ Writing unit tests for an external service function is no different to writing u
 
 ## How to write an external function PHPUnit test
 
-You should create one unit test testcase for each external service file, and it should be named after the file that it tests.
+You should create one unit test testcase for each external service class, and it should be named after the class that it tests.
 
 For example, if you have written a service function in `[componentfolder]/classes/external/get_fruit.php`, you should write a unit test in `[componentfolder]/tests/external/get_fruit_test.php`.
 
+:::note External Services Testcase
+
+An external testcase has been created to make testing external services easier.
+
+When creating your tests, you can extend the `\core_external\tests\externallib_testcase` class instead of `\advanced_testcase`.
+
+:::
+
 ```php title="mod/kitchen/tests/external/get_fruit_test.php"
 <?php
 // This file is part of Moodle - http://moodle.org/
@@ -41,28 +49,20 @@ For example, if you have written a service function in `[componentfolder]/classe
 // You should have received a copy of the GNU General Public License
 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
 
+namespace mod_kitchen\external;
+
 /**
  * Unit tests for the get_fruit function of the kitchen.
  *
  * @package    mod_kitchen
  * @category   external
- * @copyright  20XX Your Name
+ * @copyright  Your Name
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
-
-namespace mod_kitchen\external;
-
-defined('MOODLE_INTERNAL') || die();
-
-global $CFG;
-require_once($CFG->dirroot . '/webservice/tests/helpers.php');
-
-class get_fruit_test extends externallib_advanced_testcase {
-
+#[\PHPUnit\Framework\Attributes\CoversClass(get_fruit::class)]
+class get_fruit_test extends \core_external\tests\externallib_testcase {
     /**
      * Test the execute function when capabilities are present.
-     *
-     * @covers \mod_fruit\external\get_fruit::execute
      */
     public function test_capabilities(): void {
         $this->resetAfterTest(true);
@@ -96,8 +96,6 @@ class get_fruit_test extends externallib_advanced_testcase {
 
     /**
      * Test the execute function when capabilities are missing.
-     *
-     * @covers \mod_fruit\external\get_fruit::execute
      */
     public function test_capabilities_missing(): void {
         global $USER;
diff --git a/docs/devupdate.md b/docs/devupdate.md
index 98f76bbc2..8c612067a 100644
--- a/docs/devupdate.md
+++ b/docs/devupdate.md
@@ -28,3 +28,11 @@ The `maxsections` setting in course formats is now deprecated. Previously, this
 Although the `maxsections` setting remains available for now, it is marked as deprecated and will be removed in Moodle 6.0. Also, the `get_max_sections` from `core_courseformat\base` is also deprecated and will be removed in Moodle 6.0.
 
 If your format plugin relies on `maxsections`, you should add a custom setting in your plugin to control section limits. For reference, see the week format plugin, which now uses its own setting for this functionality.
+
+## Unit Testing
+
+### Testing External Service classes
+
+<Since versions={["5.1", "5.0.7", "4.5.11", "4.4.21"]} issueNumber="MDL-86301" />
+
+A new `\core_external\tests\externallib_testcase` has been introduced to replace the `\externallib_advanced_testcase` class. The new class can be autoloaded, and is available from Moodle 4.4 onwards.