Make using assign and unassign quick actions together work as expected

app/services/quick_actions/interpret_service.rb

@@ -127,18 +127,16 @@ module QuickActions
     parse_params do |assignee_param|
       extract_users(assignee_param)
     end
-    # rubocop: disable CodeReuse/ActiveRecord
     command :assign do |users|
       next if users.empty?
 
-      @updates[:assignee_ids] =
       if issuable.allows_multiple_assignees?
-          issuable.assignees.pluck(:id) + users.map(&:id)
+        @updates[:assignee_ids] ||= issuable.assignees.map(&:id)
+        @updates[:assignee_ids] += users.map(&:id)
       else
-          [users.first.id]
+        @updates[:assignee_ids] = [users.first.id]
       end
     end
-    # rubocop: enable CodeReuse/ActiveRecord
 
     desc do
       if issuable.allows_multiple_assignees?
@@ -165,16 +163,14 @@ module QuickActions
       # When multiple users are assigned, all will be unassigned if multiple assignees are no longer allowed
       extract_users(unassign_param) if issuable.allows_multiple_assignees?
     end
-    # rubocop: disable CodeReuse/ActiveRecord
     command :unassign do |users = nil|
-      @updates[:assignee_ids] =
-        if users&.any?
-          issuable.assignees.pluck(:id) - users.map(&:id)
+      if issuable.allows_multiple_assignees? && users&.any?
+        @updates[:assignee_ids] ||= issuable.assignees.map(&:id)
+        @updates[:assignee_ids] -= users.map(&:id)
       else
-          []
+        @updates[:assignee_ids] = []
       end
     end
-    # rubocop: enable CodeReuse/ActiveRecord
 
     desc 'Set milestone'
     explanation do |milestone|

changelogs/unreleased/dm-fix-assign-unassign-quick-actions.yml

+---
+title: Don't ignore first action when assign and unassign quick actions are used in
+  the same comment
+merge_request: 21749
+author:
+type: fixed