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在敏捷开发的实践中,测试驱动是少不了的。这篇来看看在rails中的一个测试驱动开发的例子。

在前面我们编写并进行了一些单元测试和功能测试,现在,我们的客户突然要求添加一个功能:系统的每个用户都可以对商品进行查询。

 我们先初步的画了一些草图,来整理我们的思路和设计,然后开始写代码。对于具体的实现,我们已经有了大致的思路,但是如果有更多的反馈信息的话会有助于我们走在正确的道路上。我们会在深入到代码之前,编写测试代码。考虑我们的代码将怎样工作,确定一些规约,当测试通过,你的代码就OK了。

现在,我们来考虑一下查询功能的测试,应该由哪个controller来控制查询操作呢?用户和管理员都可以进行查询操作,我们可以在store_controller.rb或者admin_controller.rb中添加一个search()Action,但是这里我们添加一个SearchController,并且含有一个方法search。在rails命令行执行命令:

depot>ruby script/generate controller Search search

 

我们看到,在app/controllerstest/functional目录下已经生成了对应的文件。但是现在我们并不关心SearchControllersearch方法的实现,我们关心的是在测试时我们所期望看到的结果。现在添加测试代码,在test/functional/search_controller_test.rb中添加test_search方法:

我们首先想到的是调用searchAction,然后判断是否得到了响应:

get :search, :title => "Pragmatic Version Control"

assert_response :success

 

根据之前的草图,我们应该在页面上显示一个flash信息,所以我们要判断flash信息的文本,以及是否显示了正确的页面:

assert_equal "Found 1 product(s).", flash[:notice]

assert_template "search/results"

 

然后我们想要判断查询所得到的商品信息:

products = assigns(:products)

assert_not_nil products

assert_equal 1, products.size

assert_equal "Pragmatic Version Control", products[0].title

 

我们还想判断用来显示查询结果的页面的一些内容,我们查询到的商品会作为列表在页面上显示,我们使用catelog视图相同的css样式:

assert_tag :tag => "div",

      :attributes => { :class => "results" },

      :children => { :count => 1,

      :only => { :tag => "div",

      :attributes => { :class => "catalogentry" }}}

 

下面是完整的测试方法:

def test_search

    get :search, :title => "Pragmatic Version Control"

    assert_response :success

    assert_equal "Found 1 product(s).", flash[:notice]

    assert_template "search/results"

    products = assigns(:products)

    assert_not_nil products

    assert_equal 1, products.size

    assert_equal "Pragmatic Version Control", products[0].title

    assert_tag :tag => "div",

      :attributes => { :class => "results" },

      :children => { :count => 1,

      :only => { :tag => "div",

      :attributes => { :class => "catalogentry" }}}

  end 

 

现在我们来运行测试:ruby test/functional/search_controller_test.rb

不出意外,会得到下面的结果:

test_search(SearchControllerTest) [test/functional/search_controller_test.rb:17]:

<"Found 1 product(s)."> expected but was

<nil>.

1 tests, 2 assertions, 1 failures, 0 errors

 

因为我们还没有设置flash的内容,进一步说,我们还没有实现search这个Action。怎样实现,书上给留了个作业。OK,那我们就自己来一步步实现searchAction

1.       search方法添加内容:

@products = Product.find(:all,:conditions=>['title=?',params[:title]])

    if not @products.nil?

      flash[:notice] = sprintf('Found %d product(s).',@products.size)

    end

   

    render(:action=>'results')现在运行测试,结果如下:

----------------------------------------------------------------------------

  1) Failure:

test_search(SearchControllerTest)

    [Z:/study/ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/actionpack……

     Z:/study/ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/actionpack……

     test/functional/search_controller_test.rb:19:in `test_search']:

expecting <"search/results"> but rendering with <"search/search">

1 tests, 3 assertions, 1 failures, 0 errors

----------------------------------------------------------------------------

 

2.       这次轮到assert_template "search/results"断言出错了,是因为我们还没有results这个View,我们在view目录下添加一个results.rhmtl文件,在search_controller.rb文件中添加一个results的空方法:

def results                               

end

还要在search方法中添加一句:render("search/results"),然后再运行测试,结果如下:

----------------------------------------------------------------------------

Finished in 0.125 seconds.

  1) Failure:

test_search(SearchControllerTest)

    [Z:/study/ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/…… Z:/study/ruby/InstantRails/ruby/lib/ruby/gems/1.8/gems/……

expected tag, but no tag found matching {:attributes=>{:class=>"results"}, :tag=>"div",

"<h1>Search#results</h1>\n<p>Find me in app/views/search/results.rhtml</p>\n".

<nil> is not true.

----------------------------------------------------------------------------

 

3.       现在可以看到,就只有最后一个断言assert_tag没有通过了,这个断言是对页面上的元素进行判断的,所以我们来实现results页面。仔细看看断言的内容,我们就知道只要在results.rhtml里添加两个div就可以了,下面是results.rhtml的完整内容:

<h1>Search#results</h1>

<p>Find me in app/views/search/results.rhtml</p>

<div class="results">

    <div class = "catalogentry">

    </div>

</div>

保存,然后再运行测试,激动人心的时刻来临了,所有的断言都通过了!测试OK了,下面是结果:

----------------------------------------------------------

DEPRECATION WARNING: You called render('search/result……

t Z:/study/ruby/InstantRails/ruby/lib/ruby/gems/1.8/g……

Finished in 0.094 seconds.

1 tests, 7 assertions, 0 failures, 0 errors

----------------------------------------------------------

4.       在实现search.rhtmlresults.rhtml的时候,我碰到了一些问题,用测试用例都可以选出数据来,但是通过页面就怎么也不行了,把log里的sql贴出来到phpMyAdmin里执行,也能选出数据,真不知道是怎么回事,自己对rails的理解还不深,自己胡乱写了这些代码,先把代码都帖出来,等自己对rails有更深入的理解的时候看能不能找到问题。同时也请高人指点

search_controller_test.rb:

require File.dirname(__FILE__) + '/../test_helper'

require 'search_controller'

 

# Re-raise errors caught by the controller.

class SearchController; def rescue_action(e) raise e end; end

 

class SearchControllerTest < Test::Unit::TestCase

  fixtures :products

  def setup

    @controller = SearchController.new

    @request    = ActionController::TestRequest.new

    @response   = ActionController::TestResponse.new

  end

 

  def test_search

    get :search, :title => "Pragmatic Version Control"

    assert_response :success

    assert_equal "Found 1 product(s).", flash[:notice]

    assert_template "search/results"

    products = assigns(:products)

    assert_not_nil products

    assert_equal 1, products.size

    assert_equal "Pragmatic Version Control", products[0].title

    assert_tag :tag => "div",

      :attributes => { :class => "results" },

      :children => { :count => 1,

      :only => { :tag => "div",

      :attributes => { :class => "catalogentry" }}}

  end 

end

 

search_controller.rb

class SearchController < ApplicationController

 

  def search

    print(params[:title])

    @products = Product.find(:all,:conditions=>['title=?',params[:title]])

   

    if not @products.nil?

      flash[:notice] = sprintf('Found %d product(s).',@products.size)

    end

    print(flash[:notice])

    #redirect_to(:action=>'results')

    render(:action=>'results')

  end

 

  def results

   

  end

  def index

   

  end

end

 

Views下有三个文件:index.rhtmlresults.rhtmlsearch.rhtml

index.rhtml

<html>

<%= form_tag(:action=>'search',:id=>@products) %>

    <table>

            <tr>

                    <td>Book title:</td>

                    <td><%=text_field("title","")%></td>

            </tr>

           

            <tr>

                    <td><input type="submit" value="SEARCH" /></td>

            </tr>

    </table>

<%= end_form_tag %>

</html>

 

results.rhtml

<h1>Search#results</h1>

<p>Find me in app/views/search/results.rhtml</p>

<div class="results">

    <div class = "catalogentry">

            <table cellpadding="10" cellspacing="0">

            <tr class="carttitle">

                    <td >title</td>

                    <td >description</td>

                    <td >price</td>

            </tr>

           

            <%

            printf("result:%d",@products.size)

            for product in @products

            -%>

                    <tr>

                            <td><%= product.title %></td>

                            <td><%= product.description%></td>

                            <td align="right"><%= fmt_dollars(product.price) %></td>

                    </tr>

            <% end %>

 

    </table>

    </div>

</div>

 

search.rhtml

 <html></html>