MDL-84780 course: Disabled modules are not allowed

public/course/lib.php

@@ -1483,6 +1483,10 @@ function course_allowed_module($course, $modname, ?\stdClass $user = null) {
                 supports numeric module ids. Please update your code to pass the module name.');
     }
 
+    if (!\core\plugininfo\mod::get_enabled_plugin($modname)) {
+        return false;
+    }
+
     $capability = 'mod/' . $modname . ':addinstance';
     if (!get_capability_info($capability)) {
         // Debug warning that the capability does not exist, but no more than once per page.

public/course/tests/courselib_test.php

@@ -7035,6 +7035,12 @@ final class courselib_test extends advanced_testcase {
 
         // Manager has permissions.
         $this->assertTrue(course_allowed_module($course, 'assign', $manager));
+
+        // Disable the assign module.
+        $DB->set_field('modules', 'visible', 0, ['name' => 'assign']);
+
+        // Verify that disabled modules are not allowed.
+        $this->assertFalse(course_allowed_module($course, 'assign', $manager));
     }
 
     /**