Fix NoMethodError for tag moderators channel (#11047)

* Fix NoMethodError for tag moderators channel

In development, it is possible to hit a NoMethodError when adding a tag
moderator because the "tag-moderator" slug is hard-coded.

This change helps mitigate that by adding a safe navigation operator. We
can always remove it if we decide to get rid of the hard-coded value.

Secondarily, it adds this channel to the seeds file, since we pretty
much expect it to exist.

* Move nested conditional

app/labor/assign_tag_moderator.rb

@@ -25,13 +25,14 @@ module AssignTagModerator
   end
 
   def self.add_to_chat_channels(user, tag)
-    channels = user.chat_channels
+    user_channels = user.chat_channels
 
-    ChatChannel.find_by(slug: "tag-moderators").add_users(user) unless channels.exists?(slug: "tag-moderators")
+    ChatChannel.find_by(slug: "tag-moderators")&.add_users(user) unless
+      user_channels.exists?(slug: "tag-moderators")
 
-    if tag.mod_chat_channel_id
-      ChatChannel.find(tag.mod_chat_channel_id).add_users(user) unless channels.exists?(id: tag.mod_chat_channel_id)
-    else
+    if tag.mod_chat_channel_id && !user_channels.exists?(id: tag.mod_chat_channel_id)
+      ChatChannel.find(tag.mod_chat_channel_id).add_users(user)
+    elsif tag.mod_chat_channel_id.blank?
       channel = ChatChannels::CreateWithUsers.call(
         users: ([user] + User.with_role(:mod_relations_admin)).flatten.uniq,
         channel_type: "invite_only",

db/seeds.rb

@@ -372,6 +372,13 @@ seeder.create_if_none(ChatChannel) do
     )
   end
 
+  # This channel is hard-coded in a few places
+  ChatChannel.create!(
+    channel_name: "Tag Moderators",
+    channel_type: "open",
+    slug: "tag-moderators",
+  )
+
   direct_channel = ChatChannels::CreateWithUsers.call(users: User.last(2), channel_type: "direct")
   Message.create!(
     chat_channel: direct_channel,

spec/labor/assign_tag_moderator_spec.rb

@@ -6,40 +6,65 @@ RSpec.describe AssignTagModerator, type: :labor do
   let(:mod_relator) { create(:user) }
   let(:tag_one) { create(:tag) }
   let(:tag_two) { create(:tag) }
+  let!(:channel) do
+    create(:chat_channel,
+           slug: "tag-moderators",
+           channel_name: "Tag Moderators",
+           channel_type: "invite_only")
+  end
 
-  before do
+  def add_tag_moderators
     mod_relator.add_role(:mod_relations_admin)
     user_ids = [user_one.id, user_two.id]
     tag_ids = [tag_one.id, tag_two.id]
-    ChatChannel.create(slug: "tag-moderators", channel_name: "Tag Moderators", channel_type: "invite_only")
     described_class.add_tag_moderators(user_ids, tag_ids)
   end
 
-  it "assigns the correct moderators and tags" do
-    expect(tag_two.tag_moderator_ids.count).to eq(1)
+  def destroy_tag_moderator_channel
+    channel.destroy
   end
 
-  it "assigns the mod with the tag that lines up in the array" do
-    expect(user_one.has_role?(:tag_moderator, tag_one)).to be(true)
-    expect(user_two.has_role?(:tag_moderator, tag_two)).to be(true)
+  context "when a tag moderator channel exists" do
+    before do
+      add_tag_moderators
+    end
+
+    it "assigns the correct moderators and tags" do
+      expect(tag_two.tag_moderator_ids.count).to eq(1)
+    end
+
+    it "assigns the mod with the tag that lines up in the array" do
+      expect(user_one.has_role?(:tag_moderator, tag_one)).to be(true)
+      expect(user_two.has_role?(:tag_moderator, tag_two)).to be(true)
+    end
+
+    it "adds user to tag moderator channel" do
+      expect(channel.users.count).to eq(2)
+    end
+
+    it "creates channel and adds user to channel when tag doesn't already have channel" do
+      tag_channel = ChatChannel.find_by(channel_name: "##{tag_one.name} mods")
+      expect(tag_one.reload.mod_chat_channel_id).to eq(tag_channel.id)
+      expect(user_one.chat_channels).to include(tag_channel)
+      expect(mod_relator.chat_channels).to include(tag_channel)
+    end
+
+    it "adds user to channel when tag already has channel" do
+      user_three = create(:user)
+      described_class.add_tag_moderators([user_three.id], [tag_one.id])
+      channel = ChatChannel.find_by(channel_name: "##{tag_one.name} mods")
+      expect(channel.active_users).to include(user_three)
+    end
   end
 
-  it "adds user to tag moderator channel" do
-    channel = ChatChannel.find_by(slug: "tag-moderators")
-    expect(channel.users.count).to eq(2)
-  end
+  context "when a tag moderator channel doesn't exist" do
+    before do
+      destroy_tag_moderator_channel
+    end
 
-  it "creates channel and adds user to channel when tag doesn't already have channel" do
-    channel = ChatChannel.find_by(channel_name: "##{tag_one.name} mods")
-    expect(tag_one.reload.mod_chat_channel_id).to eq(channel.id)
-    expect(user_one.chat_channels).to include(channel)
-    expect(mod_relator.chat_channels).to include(channel)
-  end
-
-  it "adds user to channel when tag already has channel" do
-    user_three = create(:user)
-    described_class.add_tag_moderators([user_three.id], [tag_one.id])
-    channel = ChatChannel.find_by(channel_name: "##{tag_one.name} mods")
-    expect(channel.active_users).to include(user_three)
+    # Regression test for https://github.com/forem/forem/pull/11047
+    it "doesn't raise a NoMethodError error" do
+      expect { add_tag_moderators }.not_to raise_error(NoMethodError)
+    end
   end
 end