diff --git a/tests/auth_plugin_test.php b/tests/auth_plugin_test.php
index c17493d..adf2f37 100644
--- a/tests/auth_plugin_test.php
+++ b/tests/auth_plugin_test.php
@@ -26,6 +26,8 @@ use external_value;
 /**
  * Tests for auth_plugin_userkey class.
  *
+ * @covers auth_plugin_userkey
+ *
  * @package    auth_userkey
  * @copyright  2016 Dmitrii Metelkin (dmitriim@catalyst-au.net)
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
diff --git a/tests/core_userkey_manager_test.php b/tests/core_userkey_manager_test.php
index fa113a7..96c135a 100644
--- a/tests/core_userkey_manager_test.php
+++ b/tests/core_userkey_manager_test.php
@@ -22,6 +22,8 @@ namespace auth_userkey;
  * Key validation is fully covered in auth_plugin_test.php file.
  * TODO: write tests for validate_key() function.
  *
+ * @covers core_userkey_manager
+ *
  * @package    auth_userkey
  * @copyright  2016 Dmitrii Metelkin (dmitriim@catalyst-au.net)
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
diff --git a/tests/externallib_test.php b/tests/externallib_test.php
index 1148b2b..77081fb 100644
--- a/tests/externallib_test.php
+++ b/tests/externallib_test.php
@@ -27,6 +27,8 @@ use context_system;
 /**
  * Tests for externallib.php.
  *
+ * @covers auth_userkey_external
+ *
  * @package    auth_userkey
  * @copyright  2016 Dmitrii Metelkin (dmitriim@catalyst-au.net)
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later