如何使用Ruby模拟类？

我正在使用minitest / mock并且想要模拟一个类.我不是试图测试模型类本身,而是试图测试服务(SomeService)与模型(SomeModel)的交互.

我想出了这个(Hack :: ClassDelegate),但我不相信这是个好主意：

require 'minitest/autorun'
require 'minitest/mock'

module Hack
  class ClassDelegate
    def self.set_delegate(delegate); @@delegate = delegate; end
    def self.method_missing(sym,*args,&block)
      @@delegate.method_missing(sym,&block)
    end 
  end
end

class TestClassDelegation < MiniTest::Unit::TestCase

  class SomeModel < Hack::ClassDelegate ; end

  class SomeService
    def delete(id)
      SomeModel.delete(id)
    end
  end

  def test_delegation
    id = '123456789'
    mock = MiniTest::Mock.new
    mock.expect(:delete,nil,[id])

    SomeModel.set_delegate(mock)
    service = SomeService.new
    service.delete(id)

    assert mock.verify
  end
end

我很确定无论如何嘲笑一个类都不是一个好主意,但我有一个遗留系统,我需要编写一些测试,并且我不想更改系统,直到我对它进行了一些测试.

解决方法

我认为这有点复杂.那这个呢：

mock = MiniTest::Mock.new
SomeService.send(:const_set,:SomeModel,mock)
mock.expect(:delete,[1])
service = SomeService.new
service.delete(1)
mock.verify
SomeService.send(:remove_const,:SomeModel)