Chore: Added tests for subscriptions_controller (#483)

Added tests for subscriptions_controller
ref: #37

app/controllers/api/base_controller.rb

@@ -1,16 +1,14 @@
 class Api::BaseController < ApplicationController
   respond_to :json
   before_action :authenticate_user!
-  unless Rails.env.development?
-    rescue_from StandardError do |exception|
-      Raven.capture_exception(exception)
-      render json: { error: '500 error', message: exception.message }.to_json, status: 500
-    end
-  end
 
   private
 
   def set_conversation
     @conversation ||= current_account.conversations.find_by(display_id: params[:conversation_id])
   end
+
+  def check_billing_enabled
+    raise ActionController::RoutingError, 'Not Found' unless ENV['BILLING_ENABLED']
+  end
 end