如何用黄瓜中的`rand`测试方法？

I have a page which either returns "No match." or one of the model objects names.
What is the best way to test it with Cucumber? Should I stub rand in Given step or should I provide something like page has either a or b? Or maybe I should provide rand parameters in scenarion outline parameter, use this parameter in Given step and use the second outline column to check the result?

我有一个页面要么返回“不匹配”。或其中一个模型对象名称。用Cucumber测试它的最佳方法是什么？我应该在给定步骤中存根rand还是应该提供像页面有a或b的东西？或者我可以在scenarion outline参数中提供rand参数，在Given步骤中使用此参数并使用第二个outline列来检查结果？

UPDATE: cookies controller example in the best traditions of Cookie Monster:

更新：饼干怪物的最佳传统中的cookie控制器示例：

cookie_controller.rb

cookie_controller.rb

  def random_cookie
    if rand(5) == 0 do
      cookie = Cookie.offset(rand(Cookie.count)).first
      response =  "You got 10 free #{cookie.type} cookies for your purchase!"
    else
      response = "Sorry, no cookies left :'("
    end
    respond_to do |format|
        format.json { render json: { response: response } }
  end

find_cookie.feature

find_cookie.feature

Scenario: Looking for cookie
    When I click "find"
    Then I should see "You got 10 free" or "Sorry, no cookies left :'("

How would Then I should see "You got 10 free" or "Sorry, no cookies left :'(" step look? I've tried something like

怎么会那么我应该看到“你有10个免费”或“对不起，没有剩下的饼干：”（“一步看？我试过像

  (page.should have_content "You got 10 free") || (page.should have_content "Sorry, no cookies left :'("

But it didn't work.

但它没有用。

3 个解决方案

#1

One of the properties of tests is that they should be repeatable: they should produce the same results each time, every time. Tests should not rely in uncontrollable params (like external resources, or random sources).

测试的一个属性是它们应该是可重复的：它们每次都应该产生相同的结果。测试不应该依赖于无法控制的参数（如外部资源或随机源）。

My point is that you will need two tests, one that checks for “You got 10 free” and another one that checks “Sorry, no cookies left”.

我的观点是你需要进行两次测试，一次检查“你有10个免费”，另一个检查“对不起，没有剩下的cookie”。

In the documentation of rand, you can find this snippet: “Kernel::srand may be used to ensure repeatable sequences of random numbers between different runs of the program.”, so if your write your scenarios with a setup step that sets the seed to some number that you know results (always) in one result or the other you will have your tests.

在rand的文档中，您可以找到以下片段：“Kernel :: srand可用于确保程序的不同运行之间的可重复序列的随机数。”，所以如果您使用设置步骤设置种子来编写场景某个数字，你知道结果（总是）在一个结果或另一个结果，你将有你的测试。

Scenario: Looking for cookie and finding it
  When I seed with X
  And click "find"
  Then I should see "You got 10 free"
Scenario: Looking for cookie and not finding it
  When I seed with Y
  And click "find"
  Then I should see "Sorry, no cookies left :'("


When /^I seed with (\d+)$/ do |seed|
  srand(seed.to_i)
end

You will need to find which seeds give you one result or the other, but once you find them, they will work forever.

你将需要找到哪种种子给你一个结果或另一个结果，但一旦你找到它们，它们将永远地工作。

#2

Don't test random behaviour as this goes against proper software design practices. Your tests should be deterministic.

不要测试随机行为，因为这违反了正确的软件设计实践。您的测试应该是确定性的。

A way to wrest control of this is to define a module or class that can be substituted or mocked as required:

取而决制的方法是定义一个可以根据需要替换或模拟的模块或类：

def random_cookie
  if CookieDealer.free_cookie?
    # ...
  end
end

The method would look like:

该方法看起来像：

require 'securerandom'

module CookieDealer
  def self.free_cookie?
    SecureRandom.random_number(5) == 0
  end
end

You can then mock the free_cookie? method to simulate various conditions.

你可以嘲笑free_cookie吗？模拟各种条件的方法。

You will, of course, want to test the free_cookies method itself in a unit test of some sort. In this case you might want to run a very large number of tests to be sure it hands out approximately the correct number of cookies.

当然，您将要在某种单元测试中测试free_cookies方法本身。在这种情况下，您可能希望运行大量测试，以确保它能够分发大约正确数量的cookie。

#3

You will want to set the random seed, perhaps storing the original to restore it after testing is done.

您将需要设置随机种子，可能存储原始文件以在测试完成后恢复它。

See documentation here: http://ruby-doc.org/core-1.9.3/Kernel.html#method-i-srand for 1.9.3 or documentation for Ruby 2.0.0 here: http://ruby-doc.org/core-2.0/Kernel.html#method-i-srand

请参阅此处的文档：http：//ruby-doc.org/core-1.9.3/Kernel.html#method-i-srand for 1.9.3或Ruby 2.0.0的文档：http：// ruby-doc。组织/芯 - 2.0 / Kernel.html＃方法-I-函数srand

#1