RSpec:如何测试 Rails 记录器的消息期望? [英] RSpec: how to test Rails logger message expectations?

问题描述

我正在尝试测试 Rails 记录器是否接收到我的某些规范中的消息.我正在使用 Logging gem.

I am trying to test that the Rails logger receives messages in some of my specs. I am using the Logging gem.

假设我有这样的课程:

class BaseWorker

  def execute
    logger.info 'Starting the worker...'
  end

end

还有一个像这样的规范:

And a spec like:

describe BaseWorker do

  it 'should log an info message' do
    base_worker = BaseWorker.new
    logger_mock = double('Logging::Rails').as_null_object
    Logging::Rails.stub_chain(:logger, :info).and_return(logger_mock)

    logger_mock.should_receive(:info).with('Starting the worker...')
    base_worker.execute
    Logging::Rails.unstub(:logger)
  end

end

我收到以下失败消息:

 Failure/Error: logger_mock.should_receive(:info).with('Starting worker...')
   (Double "Logging::Rails").info("Starting worker...")
       expected: 1 time
       received: 0 times

我尝试了几种不同的方法来通过规范.例如:

I've tried out several different approaches to get the spec to pass. This works for example:

class BaseWorker

  attr_accessor :log

  def initialize
    @log = logger
  end

  def execute
    @log.info 'Starting the worker...'
  end

end

describe BaseWorker do
  it 'should log an info message' do
    base_worker = BaseWorker.new
    logger_mock = double('logger')
    base_worker.log = logger_mock

    logger_mock.should_receive(:info).with('Starting the worker...')
    base_worker.execute
  end
end

但是必须设置一个这样的可访问实例变量似乎在这里摇尾巴.(实际上，我什至不确定为什么将 logger 复制到 @log 会使其通过.)

But having to setup an accessible instance variable like that seems like the tail is wagging the dog here. (Actually, I'm not even sure why copying logger to @log would make it pass.)

什么是测试日志记录的好解决方案?

What's a good solution for testing the logging?

推荐答案

虽然我同意您通常不想测试记录器，但有时它可能有用.

While I agree you generally don't want to test loggers, there are times it may be useful.

我对 Rails.logger 的期望取得了成功.

I have had success with expectations on Rails.logger.

使用 RSpec 已弃用的 应该 语法:

Using RSpec's deprecated should syntax:

Rails.logger.should_receive(:info).with("some message")

使用 RSpec 较新的 expect 语法:

Using RSpec's newer expect syntax:

expect(Rails.logger).to receive(:info).with("some message")

注意:在控制器和模型规范中，您必须将此行放在之前记录消息.如果你把它放在后面，你会收到这样的错误消息:

Note: In controller and model specs, you have to put this line before the message is logged. If you put it after, you'll get an error message like this:

Failure/Error: expect(Rails.logger).to receive(:info).with("some message")
       (#<ActiveSupport::Logger:0x007f27f72136c8>).info("some message")
           expected: 1 time with arguments: ("some message")
           received: 0 times

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