在rspec中测试数据库连接

Question

我设置了一个查询从数据库而不是主数据库的救援后台作业。在我的resque类中，我添加了代码来建立到从属的连接，然后在方法结束时取消建立连接。我的问题是如何在rspec中测试查询是否在方法中击中特定数据库?代码示例如下:

 class ResqueJob
  @queue = :resque_job
def self.perform(user_id)
  ActiveRecord::Base.establish_connection(
      :adapter  => "mysql2",
      :host     => "slave_database.com",
      :username => "test",
      :database => "sample"
    )
    user = User.find_by_id(current_user_id)
    #bunch of code in here
  ActiveRecord::Base.clear_active_connections! # Disconnect from slave database
 end
end

Answer 1

作为一般规则，您不应该测试库代码的行为。一旦设置了连接，就由ActiveRecord将查询发送到正确的数据库。相反，测试代码是否完成了它的那部分工作:

it "sets the database connection to the slave" do
  params = { 
      :adapter  => "mysql2",
      :host     => "slave_database.com",
      :username => "test",
      :database => "sample"
  }
  ActiveRecord::Base.should_receive(:establish_connection).with(params)
  ActiveRecord::Base.should_receive(:clear_active_connections!)
  ResqueJob.perform(user)
end