FIX: pending_assigns_reminder reminder leaking total assigned topics count (#617)

Before this commit, the reminder was leaking the total assigned topics count in the title.

In the post raw it was ensured that it was not being leaked but the title was still leaking the count.

Also add specs and updated existing specs to ensure that the count is not leaked in the title.

lib/pending_assigns_reminder.rb

@@ -55,21 +55,23 @@ class PendingAssignsReminder
     posts.find_each { |post| PostDestroyer.new(Discourse.system_user, post).destroy }
   end
 
+  def visible_topics(user)
+    Topic.listable_topics.secured(Guardian.new(user)).or(Topic.private_messages_for_user(user))
+  end
+
   def assigned_count_for(user)
     assignments =
-      Assignment.joins_with_topics.where(
-        assigned_to_id: user.id,
-        assigned_to_type: "User",
-        active: true,
-      )
+      Assignment
+        .joins_with_topics
+        .where(assigned_to_id: user.id, assigned_to_type: "User", active: true)
+        .merge(visible_topics(user))
     assignments =
       DiscoursePluginRegistry.apply_modifier(:assigned_count_for_user_query, assignments, user)
     assignments.count
   end
 
   def assigned_topics(user, order:)
-    secure =
-      Topic.listable_topics.secured(Guardian.new(user)).or(Topic.private_messages_for_user(user))
+    secure = visible_topics(user)
 
     topics =
       Topic

spec/lib/pending_assigns_reminder_spec.rb

@@ -60,7 +60,7 @@ RSpec.describe PendingAssignsReminder do
 
       expect(topic.topic_allowed_users.pluck(:user_id)).to contain_exactly(system.id, user.id)
 
-      expect(topic.title).to eq(I18n.t("pending_assigns_reminder.title", pending_assignments: 3))
+      expect(topic.title).to eq(I18n.t("pending_assigns_reminder.title", pending_assignments: 2))
 
       expect(post.raw).to include(@post1.topic.fancy_title)
       expect(post.raw).to include(@post2.topic.fancy_title)
@@ -119,6 +119,41 @@ RSpec.describe PendingAssignsReminder do
       expect(reminders_count).to eq(2)
     end
 
+    it "doesn't leak assigned topics that were moved to PM" do
+      # we already add a fail to assign when the assigned user cannot view the pm
+      # so we don't need to test that here
+      # but if we move a topic to a PM that the user can't see, we should not
+      # include it in the reminder
+      post = Fabricate(:post)
+      Assigner.new(post.topic, user).assign(user)
+      post.topic.update(archetype: Archetype.private_message, category: nil)
+      reminder.remind(user)
+
+      post = Post.last
+      topic = post.topic
+      expect(topic.title).to eq(I18n.t("pending_assigns_reminder.title", pending_assignments: 2))
+      expect(post.raw).to include(@post1.topic.fancy_title)
+      expect(post.raw).to include(@post2.topic.fancy_title)
+
+      expect(post.raw).to_not include(post.topic.fancy_title)
+    end
+
+    it "reminds about PMs" do
+      pm = Fabricate(:private_message_topic, user: user)
+      Fabricate(:post, topic: pm)
+
+      Assigner.new(pm, user).assign(user)
+      reminder.remind(user)
+
+      post = Post.last
+      topic = post.topic
+
+      expect(topic.title).to eq(I18n.t("pending_assigns_reminder.title", pending_assignments: 3))
+      expect(post.raw).to include(@post1.topic.fancy_title)
+      expect(post.raw).to include(@post2.topic.fancy_title)
+      expect(post.raw).to include(pm.fancy_title)
+    end
+
     it "closed topics aren't included as active assigns" do
       SiteSetting.unassign_on_close = true
 
@@ -130,7 +165,7 @@ RSpec.describe PendingAssignsReminder do
       post = Post.last
       topic = post.topic
 
-      expect(topic.title).to eq(I18n.t("pending_assigns_reminder.title", pending_assignments: 4))
+      expect(topic.title).to eq(I18n.t("pending_assigns_reminder.title", pending_assignments: 3))
 
       @post5.topic.update_status("closed", true, Discourse.system_user)
       expect(@post5.topic.closed).to eq(true)
@@ -140,7 +175,7 @@ RSpec.describe PendingAssignsReminder do
       post = Post.last
       topic = post.topic
 
-      expect(topic.title).to eq(I18n.t("pending_assigns_reminder.title", pending_assignments: 3))
+      expect(topic.title).to eq(I18n.t("pending_assigns_reminder.title", pending_assignments: 2))
     end
 
     context "with assigns_reminder_assigned_topics_query modifier" do
@@ -162,7 +197,7 @@ RSpec.describe PendingAssignsReminder do
     context "with assigned_count_for_user_query modifier" do
       let(:modifier_block) { Proc.new { |query, user| query.where.not(assigned_to_id: user.id) } }
       it "updates the query correctly" do
-        expect(reminder.send(:assigned_count_for, user)).to eq(3)
+        expect(reminder.send(:assigned_count_for, user)).to eq(2)
 
         plugin_instance = Plugin::Instance.new
         plugin_instance.register_modifier(:assigned_count_for_user_query, &modifier_block)