diff --git a/lib/aws-sns-message-validator/src/MessageValidator.php b/lib/aws-sns-message-validator/src/MessageValidator.php
index 474aec8..4697a31 100644
--- a/lib/aws-sns-message-validator/src/MessageValidator.php
+++ b/lib/aws-sns-message-validator/src/MessageValidator.php
@@ -62,7 +62,7 @@ private static function convertLambdaMessage(Message $lambdaMessage)
      * @param string $hostNamePattern
      */
     public function __construct(
-        callable $certClient = null,
+        ?callable $certClient = null,
         $hostNamePattern = ''
     ) {
         $this->certClient = $certClient ?: function($certUrl) {
diff --git a/tests/bounce_threshold_block_test.php b/tests/bounce_threshold_block_test.php
index ea56781..06905c5 100644
--- a/tests/bounce_threshold_block_test.php
+++ b/tests/bounce_threshold_block_test.php
@@ -15,6 +15,8 @@
 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
 
 namespace tool_emailutils;
+use PHPUnit\Framework\Attributes\CoversMethod;
+
 defined('MOODLE_INTERNAL') || die();
 
 global $CFG;
@@ -26,10 +28,10 @@
  * @copyright  2024 onwards Catalyst IT {@link http://www.catalyst-eu.net/}
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
+#[CoversMethod(hook_callbacks::class, 'before_email_to_user')]
 final class bounce_threshold_block_test extends \advanced_testcase {
     /**
      * Test that emails over the bounce threshold are blocked.
-     * @covers \tool_emailutils\hook_callbacks::before_email_to_user
      */
     public function test_bounce_threshold_block_test(): void {
         global $CFG;
diff --git a/tests/sns_client_test.php b/tests/sns_client_test.php
index 4dbd973..3b4e34e 100644
--- a/tests/sns_client_test.php
+++ b/tests/sns_client_test.php
@@ -21,6 +21,8 @@
 require_once(__DIR__ . '/../lib/aws-sns-message-validator/src/Message.php');
 
 use Aws\Sns\Message;
+use PHPUnit\Framework\Attributes\CoversMethod;
+use PHPUnit\Framework\Attributes\DataProvider;
 
 /**
  * Tests for SNS client.
@@ -30,6 +32,10 @@
  * @copyright  Catalyst IT 2024
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
+#[
+    CoversMethod(sns_client::class, '__construct'),
+    CoversMethod(sns_notification::class, 'process_notification'),
+]
 final class sns_client_test extends \advanced_testcase {
     /**
      * Test email for user in unit test */
@@ -37,8 +43,6 @@ final class sns_client_test extends \advanced_testcase {
 
     /**
      * Test required libs are installed.
-     *
-     * @covers \tool_emailutils\sns_client::__construct
      */
     public function test_lib(): void {
         // Use process message to ensure no errors from missing libs are produced.
@@ -199,15 +203,14 @@ public static function bounce_processing_provider(): array {
     /**
      * Tests the email bounce thresholds
      *
-     * @dataProvider bounce_processing_provider
      * @param string $type bounce type
      * @param string $subtype bounce subtype
      * @param int $notifications the number of notifications to process
      * @param int $sendcount the email send count
      * @param int $expectedbounces expected bounce conut
      * @param bool $overthreshold expected to be over the threshold
-     * @covers \tool_emailutils\sns_notification::process_notification()
      **/
+    #[DataProvider('bounce_processing_provider')]
     public function test_bounce_processing(
         string $type,
         string $subtype,
@@ -257,8 +260,6 @@ public function test_bounce_processing(
 
     /**
      * Tests the email delivery processing
-     *
-     * @covers \tool_emailutils\sns_notification::process_notification()
      **/
     public function test_delivery_processing(): void {
         global $CFG, $DB;
diff --git a/tests/suffix_test.php b/tests/suffix_test.php
index a0d69a3..f048018 100644
--- a/tests/suffix_test.php
+++ b/tests/suffix_test.php
@@ -16,6 +16,9 @@
 
 namespace tool_emailutils;
 
+use PHPUnit\Framework\Attributes\CoversMethod;
+use PHPUnit\Framework\Attributes\DataProvider;
+
 /**
  * Tests for DKIM default suffix.
  *
@@ -24,6 +27,11 @@
  * @copyright  Catalyst IT 2024
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
+#[
+    CoversMethod(dns_util::class, 'get_selector_suffix'),
+    CoversMethod(dns_util::class, 'get_primary_domain'),
+    CoversMethod(dns_util::class, 'get_noreply_domain'),
+]
 final class suffix_test extends \advanced_testcase {
     /**
      * Test suffix.
@@ -32,15 +40,12 @@ final class suffix_test extends \advanced_testcase {
      * @param string $noreplydomain noreply domain
      * @param string $primarydomain primary domain
      * @param string $selectorsuffix selector suffix
-     * @dataProvider dns_comparisons
-     * @covers \tool_emailutils\dns_util::get_selector_suffix
-     * @covers \tool_emailutils\dns_util::get_primary_domain
-     * @covers \tool_emailutils\dns_util::get_noreply_domain
      */
+    #[DataProvider('dns_comparisons')]
     public function test_suffix(string $lmsdomain, string $noreplydomain, string $primarydomain, string $selectorsuffix): void {
         $this->resetAfterTest();
         $mock = $this->getMockBuilder('\tool_emailutils\dns_util')
-            ->setMethods(['get_primary_domain', 'get_noreply_domain'])
+            ->onlyMethods(['get_primary_domain', 'get_noreply_domain'])
             ->getMock();
 
         $mock->expects($this->any())
diff --git a/tests/suppressionlist_test.php b/tests/suppressionlist_test.php
index abc1700..75abd6a 100644
--- a/tests/suppressionlist_test.php
+++ b/tests/suppressionlist_test.php
@@ -15,6 +15,9 @@
 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
 
 namespace tool_emailutils;
+use PHPUnit\Framework\Attributes\CoversMethod;
+use tool_emailutils\task\update_suppression_list;
+
 defined('MOODLE_INTERNAL') || die();
 
 global $CFG;
@@ -26,6 +29,7 @@
  * @copyright  2024 onwards Catalyst IT {@link http://www.catalyst-eu.net/}
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
+#[CoversMethod(update_suppression_list::class, 'execute')]
 final class suppressionlist_test extends \advanced_testcase {
     /**
      * Set up the test environment and return a configured task.
@@ -81,8 +85,6 @@ protected function prepare_test_environment(bool $enablefeature): \tool_emailuti
      * 3. Each record has the correct email and reason as per the mock data.
      * 4. A CSV file is generated with the correct headers and content matching the database.
      *
-     * @covers \tool_emailutils\task\update_suppression_list::execute
-     *
      * @return void
      * @throws \dml_exception
      */
@@ -128,7 +130,6 @@ public function test_suppression_list_update_and_export(): void {
      *
      * @return void
      * @throws \dml_exception
-     * @covers \tool_emailutils\task\update_suppression_list::execute
      */
     public function test_suppression_list_update_when_disabled(): void {
         global $DB;
diff --git a/version.php b/version.php
index 36a3fb3..f92de8e 100644
--- a/version.php
+++ b/version.php
@@ -25,9 +25,9 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$plugin->version  = 2024112901;
+$plugin->version  = 2025021900;
 $plugin->release  = 2024112901;
 $plugin->requires = 2024042200;
 $plugin->component = 'tool_emailutils';
 $plugin->maturity  = MATURITY_STABLE;
-$plugin->supported = [404, 405];
+$plugin->supported = [500, 501];