MDL-65093 core_message: dont show users with cap as blocked

It is possible that before this patch the user blocked a
teacher from messaging them, even though this would have
no effect. It is also possible for a user to block a user,
then that user gets 'promoted' to a teacher role and the
block becoming ineffective. In these cases we dont show the
user's status as blocked.

message/classes/helper.php

@@ -583,7 +583,10 @@ public static function get_member_info(int $referenceuserid, array $userids, boo
 
             // Set contact and blocked status indicators.
             $data->iscontact = ($member->contactid) ? true : false;
-            $data->isblocked = ($member->blockedid) ? true : false;
+
+            // We don't want that a user has been blocked if they can message the user anyways.
+            $canmessageifblocked = api::can_send_message($referenceuserid, $member->id, true);
+            $data->isblocked = ($member->blockedid && !$canmessageifblocked) ? true : false;
 
             $data->isdeleted = ($member->deleted) ? true : false;
 
@@ -594,9 +597,9 @@ public static function get_member_info(int $referenceuserid, array $userids, boo
                 $privacysetting = api::get_user_privacy_messaging_preference($member->id);
                 $data->requirescontact = $privacysetting == api::MESSAGE_PRIVACY_ONLYCONTACTS;
 
-                // Here we check that if the sender wanted to block the recipient, the recipient would
-                // still be able to message them regardless.
-                $data->canmessageevenifblocked = api::can_send_message($referenceuserid, $member->id, true);
+                // Here we check that if the sender wanted to block the recipient, the
+                // recipient would still be able to message them regardless.
+                $data->canmessageevenifblocked = !$data->isdeleted && $canmessageifblocked;
                 $data->canmessage = !$data->isdeleted && api::can_send_message($member->id, $referenceuserid);
             }
 

message/tests/behat/block_user.feature

@@ -41,3 +41,27 @@ Feature: To be able to block users that we are able to or to see a message if we
     And I open contact menu
     When I click on "Block" "link" in the "[data-region='header-container']" "css_element"
     Then I should see "You are unable to block Teacher 1"
+
+  Scenario: Block a user who then gets an elevated role
+    Given I log in as "student1"
+    And I select "Student 2" user in messaging
+    And I open contact menu
+    And I click on "Block" "link" in the "[data-region='header-container']" "css_element"
+    And I click on "Block" "button" in the "[data-region='confirm-dialogue']" "css_element"
+    And I log out
+    And I log in as "admin"
+    And I am on "Course 1" course homepage
+    And I navigate to course participants
+    And I click on "Unenrol" "icon" in the "student2" "table_row"
+    And I click on "Unenrol" "button" in the "Unenrol" "dialogue"
+    And I enrol "Student 2" user as "Teacher"
+    And I log out
+    And I log in as "student2"
+    And I select "Student 1" user in messaging
+    And I should not see "You are unable to message this user"
+    And I log out
+    And I log in as "student1"
+    And I select "Student 2" user in messaging
+    And I open contact menu
+    When I click on "Block" "link" in the "[data-region='header-container']" "css_element"
+    Then I should see "You are unable to block Student 2"