Rails控制器RSpec的nil：NilClass未定义方法'encode'

问题描述

我有一个带有ActiveAdmin面板的Rails 6应用程序，该面板具有一种使用管理员活动日志创建CSV文件的方法。我想为该操作创建RSpec测试，如下所示：

admin/users_spec.rb

describe Admin::UsersController,type: :controller do
  include Devise::Test::ControllerHelpers

  before { sign_in admin }

  let!(:admin) { create(:admin_user) }

  describe '#import_csv' do
    let(:csv_admin_log_generator_instance) { instance_double(::AdminLogData::CsvAdminLogGenerator) }

    before do
      allow(::AdminLogData::CsvAdminLogGenerator).to receive(:new).and_return(csv_admin_log_generator_instance)
      allow(csv_admin_log_generator_instance).to receive(:call)
      get :index
    end

    it 'accepts send_data' do
      get :import_csv
      expect(csv_admin_log_generator_instance).to receive(send_data)
    end
  end
end

但这给我一个错误：

  1) Admin::UsersController#import_csv accepts send_data
     Failure/Error:
       send_data file.encode('UTF-8'),type: 'text/csv; charset=UTF-8; header=present',disposition: 'attachment; filename=admin_logs.csv'

     NoMethodError:
       undefined method `encode' for nil:NilClass

这是我要测试的方法（其行为类似于控制器）。

  collection_action :import_csv,method: :get do
    file = ::AdminLogData::CsvAdminLogGenerator.new.call

    send_data file.encode('UTF-8'),disposition: 'attachment; filename=admin_logs.csv'
  end

解决方法

我相信问题出在allow(csv_admin_log_generator_instance).to receive(:call)，您对此方法进行了存根，其结果为nil。您需要强制它调用原始方法allow(csv_admin_log_generator_instance).to receive(:call).and_call_original

,

我发现我不需要模拟任何这些方法，而只是简单地启用paper_trail gem并按如下所示更新规范。

describe Admin::UsersController,type: :controller do
  include Devise::Test::ControllerHelpers

  let!(:admin) { create(:admin_user) }
  before do
    sign_in admin
    get :index
  end

  it_behaves_like 'controller response status',200

  describe '#import_csv' do
    it_behaves_like 'controller response status',200

    it 'create CSV file',versioning: true do
      admin.update!(email: '[e-mail]')
      get :import_csv
      expect(response.header['Content-Type']).to include 'text/csv'
    end
  end
end