Do not always show 'My certificates' profile link (#585)

lib.php

@@ -361,9 +361,16 @@ function customcert_extend_settings_navigation(settings_navigation $settings, na
  * @param stdClass $user user object
  * @param bool $iscurrentuser
  * @param stdClass $course Course object
- * @return bool
+ * @return void
  */
 function mod_customcert_myprofile_navigation(core_user\output\myprofile\tree $tree, $user, $iscurrentuser, $course) {
+    global $USER;
+
+    if (($user->id != $USER->id)
+            && !has_capability('mod/customcert:viewallcertificates', context_system::instance())) {
+        return;
+    }
+
     $params = [
         'userid' => $user->id
     ];

tests/behat/my_certificates.feature

@@ -12,9 +12,11 @@ Feature: Being able to view the certificates you have been issued
     And the following "users" exist:
       | username | firstname | lastname | email                |
       | student1 | Student   | 1        | student1@example.com |
+      | student2 | Student   | 2        | student2@example.com |
     And the following "course enrolments" exist:
       | user     | course | role    |
       | student1 | C1     | student |
+      | student2 | C1     | student |
       | student1 | C2     | student |
     And the following "activities" exist:
       | activity   | name                 | intro                      | course | idnumber    |
@@ -37,3 +39,14 @@ Feature: Being able to view the certificates you have been issued
     And I follow "My certificates"
     And I should see "Custom certificate 1"
     And I should see "Custom certificate 2"
+
+  Scenario: User does not see link for another user's certificates
+    And I log in as "student1"
+    And I am on "Course 1" course homepage
+    And I follow "Custom certificate 1"
+    And I press "View certificate"
+    And I log in as "student2"
+    And I am on "Course 1" course homepage
+    And I follow "Participants"
+    And I follow "Student 1"
+    And I should not see "My certificates"