diff --git a/classes/local/query.php b/classes/local/query.php
index d4bdc31..66c5f35 100644
--- a/classes/local/query.php
+++ b/classes/local/query.php
@@ -118,6 +118,7 @@ public function get_capability_string() {
      *
      * @param \context $context The context to check.
      * @return bool true if the user has this capability. Otherwise false.
+     * @covers \report_customsql\local\query
      */
     public function can_edit(\context $context): bool {
         return has_capability('report/customsql:definequeries', $context);
diff --git a/tests/external/external_get_users_test.php b/tests/external/external_get_users_test.php
index 3996f5f..27bef1c 100644
--- a/tests/external/external_get_users_test.php
+++ b/tests/external/external_get_users_test.php
@@ -67,9 +67,11 @@ protected function setup_users(): array {
         return [$admin, $manager, $coursecreateor];
     }
 
-    public function test_get_users_site_config() {
+    public function test_get_users_site_config(): void {
+        global $OUTPUT;
+        $defaultuserimage = $OUTPUT->image_url('u/f2');
+
         [$admin] = $this->setup_users();
-        $defaultuserimage = 'https://www.example.com/moodle/theme/image.php/_s/boost/core/1/u/f2';
 
         $result = get_users::execute('', 'moodle/site:config');
         $result = \external_api::clean_returnvalue(get_users::execute_returns(), $result);
@@ -85,9 +87,11 @@ public function test_get_users_site_config() {
         ], $result);
     }
 
-    public function test_get_users_site_viewreports() {
+    public function test_get_users_site_viewreports(): void {
+        global $OUTPUT;
+        $defaultuserimage = $OUTPUT->image_url('u/f2');
+
         [$admin, $manager] = $this->setup_users();
-        $defaultuserimage = 'https://www.example.com/moodle/theme/image.php/_s/boost/core/1/u/f2';
 
         $result = get_users::execute('', 'moodle/site:viewreports');
         $result = \external_api::clean_returnvalue(get_users::execute_returns(), $result);
@@ -110,43 +114,47 @@ public function test_get_users_site_viewreports() {
         ], $result);
     }
 
-    public function test_get_users_customsql_view() {
+    public function test_get_users_customsql_view(): void {
+        global $OUTPUT;
+        $defaultuserimage = $OUTPUT->image_url('u/f2');
+
         [$admin, $manager, $coursecreateor] = $this->setup_users();
-        $defaultuserimage = 'https://www.example.com/moodle/theme/image.php/_s/boost/core/1/u/f2';
 
         $result = get_users::execute('', 'report/customsql:view');
         $result = \external_api::clean_returnvalue(get_users::execute_returns(), $result);
 
         $this->assertEquals([
-                [
-                        'id' => $coursecreateor->id,
-                        'fullname' => fullname($coursecreateor),
-                        'identity' => 'cc@example.com',
-                        'hasidentity' => true,
-                        'profileimageurlsmall' => $defaultuserimage,
-                ],
-                [
-                        'id' => $manager->id,
-                        'fullname' => fullname($manager),
-                        'identity' => 'manager@example.com',
-                        'hasidentity' => true,
-                        'profileimageurlsmall' => $defaultuserimage,
-                ],
-                [
-                        'id' => $admin->id,
-                        'fullname' => fullname($admin),
-                        'identity' => 'admin@example.com',
-                        'hasidentity' => true,
-                        'profileimageurlsmall' => $defaultuserimage,
-                ],
+            [
+                'id' => $coursecreateor->id,
+                'fullname' => fullname($coursecreateor),
+                'identity' => 'cc@example.com',
+                'hasidentity' => true,
+                'profileimageurlsmall' => $defaultuserimage,
+            ],
+            [
+                'id' => $manager->id,
+                'fullname' => fullname($manager),
+                'identity' => 'manager@example.com',
+                'hasidentity' => true,
+                'profileimageurlsmall' => $defaultuserimage,
+            ],
+            [
+                'id' => $admin->id,
+                'fullname' => fullname($admin),
+                'identity' => 'admin@example.com',
+                'hasidentity' => true,
+                'profileimageurlsmall' => $defaultuserimage,
+            ],
         ], $result);
     }
 
-    public function test_get_users_serch_without_admins() {
+    public function test_get_users_serch_without_admins(): void {
+        global $OUTPUT;
+        $defaultuserimage = $OUTPUT->image_url('u/f2');
+
         global $OUTPUT;
 
         [, $manager] = $this->setup_users();
-        $defaultuserimage = $OUTPUT->image_url('u/f2');
 
         $result = get_users::execute('Man', 'report/customsql:view');
         $result = \external_api::clean_returnvalue(get_users::execute_returns(), $result);
@@ -162,9 +170,11 @@ public function test_get_users_serch_without_admins() {
         ], $result);
     }
 
-    public function test_get_users_serch_with_admin() {
+    public function test_get_users_serch_with_admin(): void {
+        global $OUTPUT;
+        $defaultuserimage = $OUTPUT->image_url('u/f2');
+
         [$admin] = $this->setup_users();
-        $defaultuserimage = 'https://www.example.com/moodle/theme/image.php/_s/boost/core/1/u/f2';
 
         $result = get_users::execute('n U', 'report/customsql:view');
         $result = \external_api::clean_returnvalue(get_users::execute_returns(), $result);
diff --git a/tests/local/category_test.php b/tests/local/category_test.php
index d1bd8ff..56cc30b 100644
--- a/tests/local/category_test.php
+++ b/tests/local/category_test.php
@@ -27,6 +27,7 @@
  * @package   report_customsql
  * @copyright 2021 The Open University
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @covers \report_customsql\local\category
  */
 class category_test extends \advanced_testcase {
     /**
diff --git a/tests/privacy_test.php b/tests/privacy_test.php
index 6eaa4e5..55644dc 100644
--- a/tests/privacy_test.php
+++ b/tests/privacy_test.php
@@ -25,6 +25,7 @@
  * @package    report_customsql
  * @copyright  2021 The Open University
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @covers \report_customsql\privacy\provider
  */
 class privacy_test extends \core_privacy\tests\provider_testcase {
 
diff --git a/tests/report_test.php b/tests/report_test.php
index 62b67ed..682a8df 100644
--- a/tests/report_test.php
+++ b/tests/report_test.php
@@ -61,6 +61,7 @@ public function get_week_starts_provider(): array {
      * @param string $lastweek
      *
      * @dataProvider get_week_starts_provider
+     * @covers ::report_customsql_get_week_starts
      */
     public function test_get_week_starts(
             int $startwday, string $datestr, string $currentweek, string $lastweek): void {
@@ -82,6 +83,7 @@ public function test_get_week_starts(
      * @return void
      *
      * @dataProvider get_week_starts_provider
+     * @covers ::report_customsql_get_week_starts
      */
     public function test_get_week_starts_use_calendar_default(
             int $startwday, string $datestr, string $currentweek, string $lastweek): void {
@@ -95,6 +97,7 @@ public function test_get_week_starts_use_calendar_default(
         $this->assertEquals($expected, report_customsql_get_week_starts(strtotime($datestr)));
     }
 
+    /** @covers ::report_customsql_get_month_starts */
     public function test_get_month_starts_test(): void {
         $this->assertEquals([
                 strtotime('00:00 1 November 2009'), strtotime('00:00 1 October 2009')],
@@ -109,6 +112,7 @@ public function test_get_month_starts_test(): void {
                 report_customsql_get_month_starts(strtotime('23:59 29 November 2009')));
     }
 
+    /** @covers ::report_customsql_get_element_type */
     public function test_report_customsql_get_element_type(): void {
         $this->assertEquals('date_time_selector', report_customsql_get_element_type('start_date'));
         $this->assertEquals('date_time_selector', report_customsql_get_element_type('startdate'));
@@ -120,12 +124,14 @@ public function test_report_customsql_get_element_type(): void {
         $this->assertEquals('text', report_customsql_get_element_type('mandated'));
     }
 
+    /** @covers ::report_customsql_substitute_user_token */
     public function test_report_customsql_substitute_user_token(): void {
         $this->assertEquals('SELECT COUNT(*) FROM oh_quiz_attempts WHERE user = 123',
                 report_customsql_substitute_user_token('SELECT COUNT(*) FROM oh_quiz_attempts '.
                         'WHERE user = %%USERID%%', 123));
     }
 
+    /** @covers ::report_customsql_capability_options */
     public function test_report_customsql_capability_options(): void {
         $capoptions = [
             'report/customsql:view' => get_string('anyonewhocanveiwthisreport', 'report_customsql'),
@@ -136,6 +142,7 @@ public function test_report_customsql_capability_options(): void {
 
     }
 
+    /** @covers ::report_customsql_runable_options */
     public function test_report_customsql_runable_options(): void {
         $options = [
             'manual'  => get_string('manual', 'report_customsql'),
@@ -147,6 +154,7 @@ public function test_report_customsql_runable_options(): void {
         $this->assertEquals($options, report_customsql_runable_options());
     }
 
+    /** @covers ::report_customsql_daily_at_options */
     public function test_report_customsql_daily_at_options(): void {
         $time = [];
         for ($h = 0; $h < 24; $h++) {
@@ -156,6 +164,7 @@ public function test_report_customsql_daily_at_options(): void {
         $this->assertEquals($time, report_customsql_daily_at_options());
     }
 
+    /** @covers ::report_customsql_email_options */
     public function test_report_customsql_email_options(): void {
         $options = [
             'emailnumberofrows' => get_string('emailnumberofrows', 'report_customsql'),
@@ -164,16 +173,19 @@ public function test_report_customsql_email_options(): void {
         $this->assertEquals($options, report_customsql_email_options());
     }
 
+    /** @covers ::report_customsql_bad_words_list */
     public function test_report_customsql_bad_words_list(): void {
         $options = ['ALTER', 'CREATE', 'DELETE', 'DROP', 'GRANT', 'INSERT', 'INTO', 'TRUNCATE', 'UPDATE'];
         $this->assertEquals($options, report_customsql_bad_words_list());
     }
 
+    /** @covers ::report_customsql_bad_words_list */
     public function test_report_customsql_contains_bad_word(): void {
         $string = 'DELETE * FROM prefix_user u WHERE u.id  > 0';
         $this->assertEquals(1, report_customsql_contains_bad_word($string));
     }
 
+    /** @covers ::report_customsql_get_daily_time_starts */
     public function test_report_customsql_get_ready_to_run_daily_reports(): void {
         global $DB;
         $this->resetAfterTest(true);
@@ -247,6 +259,7 @@ public function test_report_customsql_get_ready_to_run_daily_reports(): void {
         $this->assertTrue(report_customsql_is_daily_report_ready($report, $timenow));
     }
 
+    /** @covers ::report_customsql_is_integer */
     public function test_report_customsql_is_integer(): void {
         $this->assertTrue(report_customsql_is_integer(1));
         $this->assertTrue(report_customsql_is_integer('1'));
@@ -254,6 +267,7 @@ public function test_report_customsql_is_integer(): void {
         $this->assertFalse(report_customsql_is_integer('2013-10-07'));
     }
 
+    /** @covers ::report_customsql_get_table_headers */
     public function test_report_customsql_get_table_headers(): void {
         $rawheaders = [
                 'String date',
@@ -280,6 +294,7 @@ public function test_report_customsql_get_table_headers(): void {
         $this->assertEquals([3 => 4, 4 => -1, 5 => 7, 7 => -1], $linkcolumns);
     }
 
+    /** @covers ::report_customsql_pretify_column_names */
     public function test_report_customsql_pretify_column_names(): void {
         $row = new \stdClass();
         $row->column = 1;
@@ -288,9 +303,9 @@ public function test_report_customsql_pretify_column_names(): void {
         $query = "SELECT 1 AS First, 2 AS Column_URL, 3 AS column_3";
         $this->assertEquals(['column', 'Column URL', 'column 3'],
                 report_customsql_pretify_column_names($row, $query));
-
     }
 
+    /** @covers ::report_customsql_pretify_column_names */
     public function test_report_customsql_pretify_column_names_multi_line(): void {
         $row = new \stdClass();
         $row->column = 1;
@@ -303,9 +318,9 @@ public function test_report_customsql_pretify_column_names_multi_line(): void {
                     FROM table";
         $this->assertEquals(['column', 'Column URL', 'column 3'],
                 report_customsql_pretify_column_names($row, $query));
-
     }
 
+    /** @covers ::report_customsql_pretify_column_names */
     public function test_report_customsql_pretify_column_names_same_name_diff_capitialisation(): void {
         $row = new \stdClass();
         $row->course = 'B747-19B';
@@ -316,6 +331,7 @@ public function test_report_customsql_pretify_column_names_same_name_diff_capiti
 
     }
 
+    /** @covers ::report_customsql_pretify_column_names */
     public function test_report_customsql_pretify_column_names_issue(): void {
         $row = new \stdClass();
         $row->website = 'B747-19B';
@@ -346,6 +362,7 @@ public function test_report_customsql_pretify_column_names_issue(): void {
 
     }
 
+    /** @covers ::report_customsql_display_row */
     public function test_report_customsql_display_row(): void {
         $rawdata = [
                 'Not a date',
@@ -373,7 +390,7 @@ public function test_report_customsql_display_row(): void {
     /**
      * Test plugin emailing of reports
      *
-     * @return void
+     * @covers ::report_customsql_email_report
      */
     public function test_report_customsql_email_report(): void {
         global $CFG, $DB;
@@ -441,7 +458,7 @@ public function test_report_customsql_email_report(): void {
     /**
      * Test plugin downloading of reports.
      *
-     * @return void
+     * @covers ::report_customsql_downloadurl
      */
     public function test_report_custom_sql_download_report_url(): void {
         global $DB;
@@ -478,6 +495,7 @@ public function test_report_custom_sql_download_report_url(): void {
         $this->assertEquals($expected, $url->out(false));
     }
 
+    /** @covers ::report_customsql_write_csv_row */
     public function test_report_customsql_write_csv_row(): void {
         global $CFG;
         $this->resetAfterTest();