Fix results/query in `api/v1/featured_tags/suggestions` (#29597)

app/controllers/api/v1/featured_tags/suggestions_controller.rb

@@ -12,6 +12,10 @@ class Api::V1::FeaturedTags::SuggestionsController < Api::BaseController
   private
 
   def set_recently_used_tags
-    @recently_used_tags = Tag.recently_used(current_account).where.not(id: current_account.featured_tags).limit(10)
+    @recently_used_tags = Tag.recently_used(current_account).where.not(id: featured_tag_ids).limit(10)
+  end
+
+  def featured_tag_ids
+    current_account.featured_tags.pluck(:tag_id)
   end
 end

spec/controllers/api/v1/featured_tags/suggestions_controller_spec.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe Api::V1::FeaturedTags::SuggestionsController do
+  render_views
+
+  let(:user)    { Fabricate(:user) }
+  let(:token)   { Fabricate(:accessible_access_token, resource_owner_id: user.id, scopes: 'read:accounts') }
+  let(:account) { Fabricate(:account, user: user) }
+
+  before do
+    allow(controller).to receive(:doorkeeper_token) { token }
+  end
+
+  describe 'GET #index' do
+    let!(:unused_featured_tag) { Fabricate(:tag, name: 'unused_featured_tag') }
+    let!(:used_tag) { Fabricate(:tag, name: 'used_tag') }
+    let!(:used_featured_tag) { Fabricate(:tag, name: 'used_featured_tag') }
+
+    before do
+      _unused_tag = Fabricate(:tag, name: 'unused_tag')
+
+      # Make relevant tags used by account
+      status = Fabricate(:status, account: account)
+      status.tags << used_tag
+      status.tags << used_featured_tag
+
+      # Feature the relevant tags
+      Fabricate :featured_tag, account: account, name: unused_featured_tag.name
+      Fabricate :featured_tag, account: account, name: used_featured_tag.name
+    end
+
+    it 'returns http success and recently used but not featured tags', :aggregate_failures do
+      get :index, params: { account_id: account.id, limit: 2 }
+
+      expect(response)
+        .to have_http_status(200)
+      expect(body_as_json)
+        .to contain_exactly(
+          include(name: used_tag.name)
+        )
+    end
+  end
+end