Fix #5953 - Add GET /api/v1/accounts/:id/lists (#5983)

app/controllers/api/v1/accounts/lists_controller.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+class Api::V1::Accounts::ListsController < Api::BaseController
+  before_action -> { doorkeeper_authorize! :read }
+  before_action :require_user!
+  before_action :set_account
+
+  respond_to :json
+
+  def index
+    @lists = @account.lists.where(account: current_account)
+    render json: @lists, each_serializer: REST::ListSerializer
+  end
+
+  private
+
+  def set_account
+    @account = Account.find(params[:account_id])
+  end
+end

config/routes.rb

@@ -269,6 +269,7 @@ Rails.application.routes.draw do
         resources :statuses, only: :index, controller: 'accounts/statuses'
         resources :followers, only: :index, controller: 'accounts/follower_accounts'
         resources :following, only: :index, controller: 'accounts/following_accounts'
+        resources :lists, only: :index, controller: 'accounts/lists'
 
         member do
           post :follow

spec/controllers/api/v1/accounts/lists_controller_spec.rb

@@ -0,0 +1,23 @@
+require 'rails_helper'
+
+describe Api::V1::Accounts::ListsController do
+  render_views
+
+  let(:user)    { Fabricate(:user, account: Fabricate(:account, username: 'alice')) }
+  let(:token)   { Fabricate(:accessible_access_token, resource_owner_id: user.id, scopes: 'read') }
+  let(:account) { Fabricate(:account) }
+  let(:list)    { Fabricate(:list, account: user.account) }
+
+  before do
+    allow(controller).to receive(:doorkeeper_token) { token }
+    user.account.follow!(account)
+    list.accounts << account
+  end
+
+  describe 'GET #index' do
+    it 'returns http success' do
+      get :index, params: { account_id: account.id }
+      expect(response).to have_http_status(:success)
+    end
+  end
+end