Rails - Singleton class troubles with rspec feature

问题

I have a problem testing a functionality that depends of a Singleton class. That class (ERPDao) is a suite with diferent methods that helps application to connect with external ERP vía REST services using Faraday gem. URLMaker is a helper class for build requests strings. When i try to run a feature spec that depends of one of this methods i have the following message in rspec:

 Failure/Error: result = ERPDao.instance.get_credit_info(erp_id)

 NoMethodError:
   undefined method `instance' for ERPDao:Class
   Did you mean?  instance_of?
   Did you mean?  instance_of?

My class ERPDao

class ERPDao
def initialize
    @end_points = EndPoint.first
    @connection = Faraday.new(:url => @end_points.url_base, request: {
      open_timeout: 10,   # opening a connection
      timeout: 10         # waiting for response
    })
end
@@instance = ERPDao.new

def self.instance
    return @@instance
end

def get_credit_info(erp_id)
    begin
        return @connection.get URLMaker.instance.get_uri('credit_info', erp_id)
    rescue Faraday::Error::ConnectionFailed => e
        puts "Connection failed: #{e}"
        return 0, false, 0
    end
end

    ...
end

My rails_helper.rb

require 'spec_helper'
ENV['RAILS_ENV'] ||= 'test'
require File.expand_path('../../config/environment', __FILE__)
abort("The Rails environment is running in production mode!") if Rails.env.production?
require 'rspec/rails'
require 'support/factory_bot'
require 'support/wait_for_ajax'
ActiveRecord::Migration.maintain_test_schema!

RSpec.configure do |config|
  config.fixture_path = "#{::Rails.root}/spec/fixtures"
  config.use_transactional_fixtures = false

  config.before :suite do
    DatabaseCleaner.strategy = :truncation
  end

  config.before :each do
    DatabaseCleaner.clean
  end
  config.infer_spec_type_from_file_location!
  config.filter_rails_from_backtrace!
  config.include Warden::Test::Helpers

  config.include Devise::TestHelpers, type: :controller

  Shoulda::Matchers.configure do |config|
    config.integrate do |with|
      with.test_framework :rspec
      with.library :rails
    end
  end
  Capybara.javascript_driver = :webkit

  Capybara::Webkit.configure do |config|
    config.debug = false
    config.allow_unknown_urls
    config.skip_image_loading
    config.timeout = 15
    config.raise_javascript_errors = false
  end
end

My version of rails is 4.2.6, ruby 2.3.1, factory_bot 4.8.2 and rspec-rails 3.7. Someone knows about this error? Thanks!

回答1:

ERPDao is [also] being defined somewhere else. Maybe someone decided to add a method to it by re-opening the class like

class ERPDao
  def some_new_method
    ...
  end
end

Don't do that. Use modules and prepend instead.

module HasMyNewMethod
  def some_new_method
    ...
  end
end
ERPDau.prepend HasMyNewMethod

Otherwise you end up accidentally referencing the re-opening of the class and that becomes the definition - so the autoloader doesn't load it since it's already defined.

Search your codebase for 'class ERPDao'. Modify the ones that are not the initial declaration.

来源：https://stackoverflow.com/questions/58863185/rails-singleton-class-troubles-with-rspec-feature

标签

ruby-on-rails

ruby

rspec

automated-tests

singleton