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()的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/controllers和test/functional目录下已经生成了对应的文件。但是现在我们并不关心SearchController的search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search的Action,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 productsassert_equal 1, products.sizeassert_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search的Action。
1.给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:
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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
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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:
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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.
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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:
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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
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4.在实现search.rhtml和results.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; endclass 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 endsearch_controller.rbclass 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 endend
Views下有三个文件:index.rhtml,results.rhtml,search.rhtml
index.rhtml:
<html><br /><%= form_tag(:action=>'search',:id=>@products) %><br /> <table><br /> <tr><br /> <td>Book title:</td><br /> <td><%=text_field("title","")%></td><br /> </tr><br /> <tr><br /> <td><input type="submit" value="SEARCH" /></td><br /> </tr><br /> </table><br /><%= end_form_tag %><br /></html>
results.rhtml:
<h1>Search#results</h1><br /><p>Find me in app/views/search/results.rhtml</p><br /><div class="results"><br /> <div class = "catalogentry"><br /> <table cellpadding="10" cellspacing="0"><br /> <tr class="carttitle"><br /> <td >title</td><br /> <td >description</td><br /> <td >price</td><br /> </tr><br /> <%<br /> printf("result:%d",@products.size)<br /> for product in @products<br /> -%><br /> <tr><br /> <td><%= product.title %></td><br /> <td><%= product.description%></td><br /> <td align="right"><%= fmt_dollars(product.price) %></td><br /> </tr><br /> <% end %><br /> </table><br /> </div><br /></div>
search.rhtml:
<html></html>
而做人的能力则会给你一百种机会。