diff --git a/lib/external/tests/util_test.php b/lib/external/tests/util_test.php
new file mode 100644
index 00000000000..1eefdad8786
--- /dev/null
+++ b/lib/external/tests/util_test.php
@@ -0,0 +1,198 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace core_external;
+
+/**
+ * Unit tests for core_external\util.
+ *
+ * @package     core_external
+ * @category    test
+ * @copyright   2022 Andrew Lyons <andrew@nicols.co.uk>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU Public License
+ * @covers      \core_external\util
+ */
+class util_test extends \advanced_testcase {
+    /** @var \moodle_database The database connection */
+    protected $db;
+
+    /**
+     * Store the global DB for restore between tests.
+     */
+    public function setUp(): void {
+        global $DB;
+        $this->db = $DB;
+    }
+
+    /**
+     * Reset the global DB between tests.
+     */
+    public function tearDown(): void {
+        global $DB;
+        if ($this->db !== null) {
+            $DB = $this->db;
+        }
+    }
+
+    /**
+     * Validate courses, but still return courses even if they fail validation.
+     *
+     * @covers \core_external\util::validate_courses
+     */
+    public function test_validate_courses_keepfails(): void {
+        $this->resetAfterTest(true);
+
+        $c1 = $this->getDataGenerator()->create_course();
+        $c2 = $this->getDataGenerator()->create_course();
+        $c3 = $this->getDataGenerator()->create_course();
+        $u1 = $this->getDataGenerator()->create_user();
+        $this->getDataGenerator()->enrol_user($u1->id, $c1->id);
+        $courseids = [$c1->id, $c2->id, $c3->id];
+
+        $this->setUser($u1);
+        [$courses, $warnings] = util::validate_courses($courseids, [], false, true);
+        $this->assertCount(2, $warnings);
+        $this->assertEquals($c2->id, $warnings[0]['itemid']);
+        $this->assertEquals($c3->id, $warnings[1]['itemid']);
+        $this->assertCount(3, $courses);
+        $this->assertTrue($courses[$c1->id]->contextvalidated);
+        $this->assertFalse($courses[$c2->id]->contextvalidated);
+        $this->assertFalse($courses[$c3->id]->contextvalidated);
+    }
+
+    /**
+     * Validate courses can re-use an array of prefetched courses.
+     *
+     * @covers \core_external\util::validate_courses
+     */
+    public function test_validate_courses_prefetch(): void {
+        $this->resetAfterTest(true);
+
+        $c1 = $this->getDataGenerator()->create_course();
+        $c2 = $this->getDataGenerator()->create_course();
+        $c3 = $this->getDataGenerator()->create_course();
+        $c4 = $this->getDataGenerator()->create_course();
+        $u1 = $this->getDataGenerator()->create_user();
+        $this->getDataGenerator()->enrol_user($u1->id, $c1->id);
+        $this->getDataGenerator()->enrol_user($u1->id, $c2->id);
+
+        $courseids = [$c1->id, $c2->id, $c3->id];
+        $courses = [$c2->id => $c2, $c3->id => $c3, $c4->id => $c4];
+
+        $this->setUser($u1);
+        list($courses, $warnings) = util::validate_courses($courseids, $courses);
+        $this->assertCount(2, $courses);
+        $this->assertCount(1, $warnings);
+        $this->assertArrayHasKey($c1->id, $courses);
+        $this->assertSame($c2, $courses[$c2->id]);
+        $this->assertArrayNotHasKey($c3->id, $courses);
+        // The extra course passed is not returned.
+        $this->assertArrayNotHasKey($c4->id, $courses);
+    }
+
+    /**
+     * Test the Validate courses standard functionality.
+     *
+     * @covers \core_external\util::validate_courses
+     */
+    public function test_validate_courses(): void {
+        $this->resetAfterTest(true);
+
+        $c1 = $this->getDataGenerator()->create_course();
+        $c2 = $this->getDataGenerator()->create_course();
+        $c3 = $this->getDataGenerator()->create_course();
+        $u1 = $this->getDataGenerator()->create_user();
+        $this->getDataGenerator()->enrol_user($u1->id, $c1->id);
+        $courseids = [$c1->id, $c2->id, $c3->id];
+
+        $this->setAdminUser();
+        [$courses, $warnings] = \external_util::validate_courses($courseids);
+        $this->assertEmpty($warnings);
+        $this->assertCount(3, $courses);
+        $this->assertArrayHasKey($c1->id, $courses);
+        $this->assertArrayHasKey($c2->id, $courses);
+        $this->assertArrayHasKey($c3->id, $courses);
+        $this->assertEquals($c1->id, $courses[$c1->id]->id);
+        $this->assertEquals($c2->id, $courses[$c2->id]->id);
+        $this->assertEquals($c3->id, $courses[$c3->id]->id);
+
+        $this->setUser($u1);
+        [$courses, $warnings] = \external_util::validate_courses($courseids);
+        $this->assertCount(2, $warnings);
+        $this->assertEquals($c2->id, $warnings[0]['itemid']);
+        $this->assertEquals($c3->id, $warnings[1]['itemid']);
+        $this->assertCount(1, $courses);
+        $this->assertArrayHasKey($c1->id, $courses);
+        $this->assertArrayNotHasKey($c2->id, $courses);
+        $this->assertArrayNotHasKey($c3->id, $courses);
+        $this->assertEquals($c1->id, $courses[$c1->id]->id);
+    }
+
+    /**
+     * Text util::get_area_files
+     *
+     * @covers \core_external\util::get_area_files
+     */
+    public function test_external_util_get_area_files(): void {
+        global $CFG, $DB;
+
+        $this->DB = $DB;
+        $DB = $this->getMockBuilder('moodle_database')->getMock();
+
+        $content = base64_encode("Let us create a nice simple file.");
+        $timemodified = 102030405;
+        $itemid = 42;
+        $filesize = strlen($content);
+
+        $DB->method('get_records_sql')->willReturn([
+            (object) [
+                'filename'      => 'example.txt',
+                'filepath'      => '/',
+                'mimetype'      => 'text/plain',
+                'filesize'      => $filesize,
+                'timemodified'  => $timemodified,
+                'itemid'        => $itemid,
+                'pathnamehash'  => sha1('/example.txt'),
+            ],
+        ]);
+
+        $component = 'mod_foo';
+        $filearea = 'area';
+        $context = 12345;
+
+        $expectedfiles[] = [
+            'filename' => 'example.txt',
+            'filepath' => '/',
+            'fileurl' => "{$CFG->wwwroot}/webservice/pluginfile.php/{$context}/{$component}/{$filearea}/{$itemid}/example.txt",
+            'timemodified' => $timemodified,
+            'filesize' => $filesize,
+            'mimetype' => 'text/plain',
+            'isexternalfile' => false,
+        ];
+        // Get all the files for the area.
+        $files = util::get_area_files($context, $component, $filearea, false);
+        $this->assertEquals($expectedfiles, $files);
+
+        $DB->method('get_in_or_equal')->willReturn([
+            '= :mock1',
+            ['mock1' => $itemid],
+        ]);
+
+        // Get just the file indicated by $itemid.
+        $files = util::get_area_files($context, $component, $filearea, $itemid);
+        $this->assertEquals($expectedfiles, $files);
+    }
+}
diff --git a/lib/tests/externallib_test.php b/lib/tests/externallib_test.php
index 18d3814942c..df82f185175 100644
--- a/lib/tests/externallib_test.php
+++ b/lib/tests/externallib_test.php
@@ -30,19 +30,6 @@ require_once($CFG->libdir . '/externallib.php');
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 class externallib_test extends \advanced_testcase {
-    protected $DB;
-
-    public function setUp(): void {
-        $this->DB = null;
-    }
-
-    public function tearDown(): void {
-        global $DB;
-        if ($this->DB !== null) {
-            $DB = $this->DB;
-        }
-    }
-
     public function test_external_format_text() {
         $settings = \external_settings::get_instance();
 
@@ -184,145 +171,6 @@ class externallib_test extends \advanced_testcase {
         $settings->set_filter($currentfilter);
     }
 
-    public function test_validate_courses() {
-        $this->resetAfterTest(true);
-
-        $c1 = $this->getDataGenerator()->create_course();
-        $c2 = $this->getDataGenerator()->create_course();
-        $c3 = $this->getDataGenerator()->create_course();
-        $u1 = $this->getDataGenerator()->create_user();
-        $this->getDataGenerator()->enrol_user($u1->id, $c1->id);
-        $courseids = array($c1->id, $c2->id, $c3->id);
-
-        $this->setAdminUser();
-        list($courses, $warnings) = \external_util::validate_courses($courseids);
-        $this->assertEmpty($warnings);
-        $this->assertCount(3, $courses);
-        $this->assertArrayHasKey($c1->id, $courses);
-        $this->assertArrayHasKey($c2->id, $courses);
-        $this->assertArrayHasKey($c3->id, $courses);
-        $this->assertEquals($c1->id, $courses[$c1->id]->id);
-        $this->assertEquals($c2->id, $courses[$c2->id]->id);
-        $this->assertEquals($c3->id, $courses[$c3->id]->id);
-
-        $this->setUser($u1);
-        list($courses, $warnings) = \external_util::validate_courses($courseids);
-        $this->assertCount(2, $warnings);
-        $this->assertEquals($c2->id, $warnings[0]['itemid']);
-        $this->assertEquals($c3->id, $warnings[1]['itemid']);
-        $this->assertCount(1, $courses);
-        $this->assertArrayHasKey($c1->id, $courses);
-        $this->assertArrayNotHasKey($c2->id, $courses);
-        $this->assertArrayNotHasKey($c3->id, $courses);
-        $this->assertEquals($c1->id, $courses[$c1->id]->id);
-    }
-
-    /**
-     * Validate courses, but still return courses even if they fail validation.
-     */
-    public function test_validate_courses_keepfails() {
-        $this->resetAfterTest(true);
-
-        $c1 = $this->getDataGenerator()->create_course();
-        $c2 = $this->getDataGenerator()->create_course();
-        $c3 = $this->getDataGenerator()->create_course();
-        $u1 = $this->getDataGenerator()->create_user();
-        $this->getDataGenerator()->enrol_user($u1->id, $c1->id);
-        $courseids = array($c1->id, $c2->id, $c3->id);
-
-        $this->setUser($u1);
-        list($courses, $warnings) = \external_util::validate_courses($courseids, [], false, true);
-        $this->assertCount(2, $warnings);
-        $this->assertEquals($c2->id, $warnings[0]['itemid']);
-        $this->assertEquals($c3->id, $warnings[1]['itemid']);
-        $this->assertCount(3, $courses);
-        $this->assertTrue($courses[$c1->id]->contextvalidated);
-        $this->assertFalse($courses[$c2->id]->contextvalidated);
-        $this->assertFalse($courses[$c3->id]->contextvalidated);
-    }
-
-    /**
-     * Validate courses can re-use an array of prefetched courses.
-     */
-    public function test_validate_courses_prefetch() {
-        $this->resetAfterTest(true);
-
-        $c1 = $this->getDataGenerator()->create_course();
-        $c2 = $this->getDataGenerator()->create_course();
-        $c3 = $this->getDataGenerator()->create_course();
-        $c4 = $this->getDataGenerator()->create_course();
-        $u1 = $this->getDataGenerator()->create_user();
-        $this->getDataGenerator()->enrol_user($u1->id, $c1->id);
-        $this->getDataGenerator()->enrol_user($u1->id, $c2->id);
-
-        $courseids = array($c1->id, $c2->id, $c3->id);
-        $courses = array($c2->id => $c2, $c3->id => $c3, $c4->id => $c4);
-
-        $this->setUser($u1);
-        list($courses, $warnings) = \external_util::validate_courses($courseids, $courses);
-        $this->assertCount(2, $courses);
-        $this->assertCount(1, $warnings);
-        $this->assertArrayHasKey($c1->id, $courses);
-        $this->assertSame($c2, $courses[$c2->id]);
-        $this->assertArrayNotHasKey($c3->id, $courses);
-        // The extra course passed is not returned.
-        $this->assertArrayNotHasKey($c4->id, $courses);
-    }
-
-    /**
-     * Text \external_util::get_area_files
-     */
-    public function test_external_util_get_area_files() {
-        global $CFG, $DB;
-
-        $this->DB = $DB;
-        $DB = $this->getMockBuilder('moodle_database')->getMock();
-
-        $content = base64_encode("Let us create a nice simple file.");
-        $timemodified = 102030405;
-        $itemid = 42;
-        $filesize = strlen($content);
-
-        $DB->method('get_records_sql')->willReturn([
-            (object) [
-                'filename'      => 'example.txt',
-                'filepath'      => '/',
-                'mimetype'      => 'text/plain',
-                'filesize'      => $filesize,
-                'timemodified'  => $timemodified,
-                'itemid'        => $itemid,
-                'pathnamehash'  => sha1('/example.txt'),
-            ],
-        ]);
-
-        $component = 'mod_foo';
-        $filearea = 'area';
-        $context = 12345;
-
-        $expectedfiles[] = array(
-            'filename' => 'example.txt',
-            'filepath' => '/',
-            'fileurl' => "{$CFG->wwwroot}/webservice/pluginfile.php/{$context}/{$component}/{$filearea}/{$itemid}/example.txt",
-            'timemodified' => $timemodified,
-            'filesize' => $filesize,
-            'mimetype' => 'text/plain',
-            'isexternalfile' => false,
-        );
-        // Get all the files for the area.
-        $files = \external_util::get_area_files($context, $component, $filearea, false);
-        $this->assertEquals($expectedfiles, $files);
-
-        $DB->method('get_in_or_equal')->willReturn([
-            '= :mock1',
-            ['mock1' => $itemid]
-        ]);
-
-        // Get just the file indicated by $itemid.
-        $files = \external_util::get_area_files($context, $component, $filearea, $itemid);
-        $this->assertEquals($expectedfiles, $files);
-
-    }
-
     /**
      * Test default time for user created tokens.
      */