DEV: more tests for mentions when updating chat messages (#21185)

This adds these two new test cases:

    context "when updating a mentioned user" do
      it "updates the mention record" do

    # and
    context "when there are duplicate mentions" do
        it "creates a single mention record per mention" do

Apart from that, this groups mention related tests into a context, renames one test, and moves setup of another test into the test case itself from the before block (to make it more clear, that test is the only one that uses that setup). See the PR's commit history.

plugins/chat/spec/components/chat/message_updater_spec.rb

@@ -30,8 +30,6 @@ describe Chat::MessageUpdater do
       Fabricate(:user_chat_channel_membership, chat_channel: public_chat_channel, user: user)
     end
     Group.refresh_automatic_groups!
-    @direct_message_channel =
-      Chat::DirectMessageChannelCreator.create!(acting_user: user1, target_users: [user1, user2])
   end
 
   def create_chat_message(user, message, channel, upload_ids: nil)
@@ -126,6 +124,7 @@ describe Chat::MessageUpdater do
     expect(events.map { _1[:event_name] }).to include(:chat_message_edited)
   end
 
+  context "with mentions" do
     it "sends notifications if a message was updated with new mentions" do
       message = create_chat_message(user1, "Mentioning @#{user2.username}", public_chat_channel)
 
@@ -165,9 +164,13 @@ describe Chat::MessageUpdater do
       expect(mention.notification).to be_nil
     end
 
-  it "destroys mention notifications that should be removed" do
+    it "destroys mentions that should be removed" do
       chat_message =
-      create_chat_message(user1, "ping @#{user2.username} @#{user3.username}", public_chat_channel)
+        create_chat_message(
+          user1,
+          "ping @#{user2.username} @#{user3.username}",
+          public_chat_channel,
+        )
       expect {
         Chat::MessageUpdater.update(
           guardian: guardian,
@@ -179,7 +182,11 @@ describe Chat::MessageUpdater do
 
     it "creates new, leaves existing, and removes old mentions all at once" do
       chat_message =
-      create_chat_message(user1, "ping @#{user2.username} @#{user3.username}", public_chat_channel)
+        create_chat_message(
+          user1,
+          "ping @#{user2.username} @#{user3.username}",
+          public_chat_channel,
+        )
       Chat::MessageUpdater.update(
         guardian: guardian,
         chat_message: chat_message,
@@ -192,7 +199,9 @@ describe Chat::MessageUpdater do
     end
 
     it "doesn't create mention notification in direct message for users without access" do
-    message = create_chat_message(user1, "ping nobody", @direct_message_channel)
+      direct_message_channel =
+        Chat::DirectMessageChannelCreator.create!(acting_user: user1, target_users: [user1, user2])
+      message = create_chat_message(user1, "ping nobody", direct_message_channel)
 
       Chat::MessageUpdater.update(
         guardian: guardian,
@@ -204,6 +213,39 @@ describe Chat::MessageUpdater do
       expect(mention.notification).to be_nil
     end
 
+    context "when updating a mentioned user" do
+      it "updates the mention record" do
+        chat_message = create_chat_message(user1, "ping @#{user2.username}", public_chat_channel)
+
+        Chat::MessageUpdater.update(
+          guardian: guardian,
+          chat_message: chat_message,
+          new_content: "ping @#{user3.username}",
+        )
+
+        user2_mentions = user2.chat_mentions.where(chat_message: chat_message)
+        expect(user2_mentions.length).to be(0)
+
+        user3_mentions = user3.chat_mentions.where(chat_message: chat_message)
+        expect(user3_mentions.length).to be(1)
+      end
+    end
+
+    context "when there are duplicate mentions" do
+      it "creates a single mention record per user" do
+        chat_message = create_chat_message(user1, "ping @#{user2.username}", public_chat_channel)
+
+        Chat::MessageUpdater.update(
+          guardian: guardian,
+          chat_message: chat_message,
+          new_content: "ping @#{user2.username} @#{user2.username} edited",
+        )
+
+        expect(user2.chat_mentions.where(chat_message: chat_message).count).to eq(1)
+      end
+    end
+  end
+
   describe "group mentions" do
     it "creates group mentions on update" do
       chat_message = create_chat_message(user1, "ping nobody", public_chat_channel)