RSpec学习笔记

[b]前面这部分参考自：[url]http://www.letrails.cn/archives/20/[/url] 作者：zhangyuanyi[/b]

安装很简单：

gem install rspec

如果要在rails里边使用，最好再装一个rspec on rails：

gem install rspec-rails

RSpec代码用spec命令执行，比如：

spec user_spec.rb

specdoc参数格式化行为（describe方法创建的对象）以及样例（it方法创建的对象）的名字然后输出：

spec user_spec.rb --format specdoc

should方法：第一个参数叫做macher，比如

'foo'.should == 'foo'
'foo'.should === 'foo'
'foo'.should_not equal('foo')
''.should be_empty

这里面的==, ===, equal, be_empty都是macher。macher有很多种，我没有仔细去研究，rspec的源代码位置：gems\rspec-1.2.8\lib\spec\matchers
gems\rspec-1.2.8\lib\spec\expectations\extensions中有个kernel.rb，扩展了ruby的kernel，上面提到的should方法就是在这定义的，另一个是它的反义词should_not。

各种macher的用法见：[url]http://www.letrails.cn/archives/11-02-advanced-rspec-tutorials-basics/[/url]
其中那个be_close的注释不太对，只能说在那个例子中是对的，试一下 200.should be_close(80,21)，看看输出结果就知道它的意思：[quote]expected 80 +/- (< 21), got 200[/quote]

暂时先记到这，关于页面的测试，只找到这么一篇文章：
[url]http://blackanger.blog.51cto.com/140924/64189[/url]

先看The Rails Way第18章去，似乎找到的所有资料中，也就The Rails Way的第18章讲得最详细了（该死的国内某出版社），回头再完善这篇笔记。
==========================================================
The Rails Way 18章笔记

[quote]Listing 18.1 is part of a real-world RSpec script defining the behavior of a CreditCard model class.[/quote]

describe "A valid credit card" do
 before(:each) do
  @credit_card = generate_credit_card
 end

 it "should be valid after saving" do
  @credit_card.save
  @credit_card.should be_valid
 end
end

[quote]RSpec scripts are collections of behaviors, which in turn have collections of examples.Line 1 uses the [i]describe [/i]method to create a Behavior object under the covers.The behavior sets the context for a set of specification examples, and you should pass it a sentence fragment that accurately describes the context you're about to specify.
The [i]before [/i]method on line 2 (and its companion [i]after[/i]) are akin to the [i]setup [/i]and [i]teardown [/i]methods of xUnit frameworks like Test::Unit. They are used to set up the state as it should be prior to running an example, and if necessary, to clean up the state after the example has run. This particular behavior did not require an [i]after[/i] block.[/quote]
[quote]The [i]it[/i] method on line 6 is used to create an Example object, and you also give it a description. The idea is to complete the thought that was started in the [i]describe [/i]method, so that it forms a complete sentence. Our example reads "A valid credit card should be valid after saving." See it?[/quote]
[quote]Moving on, line 7 of Listing 18.1 invokes save on the credit card object, and since it's an ActiveRecord model, we know that will get it validated. So all we have left is to verify that the credit card instance is valid. Rather than xUnit-style assertions, RSpec introduces some funky DSL-ish syntax to do verification, based on a pair of methods called should and should_not.[/quote]
这里好像有点问题，rails中，model的valid?方法并不一定要在save方法之后调用，而是任何时候都可以调用的。所以这里的should be_valid之前没有什么必要调用save方法。
[quote]RSpec mixes [i]should [/i]and [i]should_not[/i] into the base Ruby Object class at runtime so that they are available on all objects. They expect to receive Matcher objects, which you generate using RSpec expectation syntax.[/quote]
如前面所说，RSpec直接往kernel里添加了should和should_not方法，而Ruby的Object class是mixin了Kernel模块的，所以这里说：RSpec mixes [i]should [/i]and [i]should_not[/i] into the base Ruby Object class at runtime

代码中有个叫be_valid的macher，这些macher并不是RSpec中预定义的方法，而是通过method_missing来实现的。这些以be_开头的macher一旦被调用，RSpec会根据macher的名字剩下的那部分去查找对象中对应的布尔型的方法。如：

collection.should be_empty #passes if target.empty?
target.should_not be_empty # passes unless target.empty?
target.should_not be_under_age(13) # passes unless target.under_age?(13)

还有一些硬编码了的macher用于判断布尔值和nil：

target.should be_true
target.should be_false
target.should be_nil
target.should_not be_nil

为了使代码读起来更自然，RSpec还提供了两个带不定冠词(a和an)的macher：be_a_和be_an_，用法和be_一样，只需要注意一下英文的语法（当然这不是必须的）：

"a string".should be_an_instance_of(String)
3.should be_a_kind_of(Fixnum)
3.should be_a_kind_of(Numeric)
3.should be_an_instance_of(Fixnum)
3.should_not be_instance_of(Numeric) #fails

[quote]RSpec will even understand [i]have_[/i] prefixes as referring to predicates like has_key?:

{:foo => “foo”}.should have_key(:foo)
{:bar => “bar”}.should_not have_key(:foo)

[/quote]

[quote]RSpec has a number of expectation matchers for working with classes that implement module Enumerable. You can specify whether an array should include a particular element, or if a string contains a substring.

[1, 2, 3].should include(1)
[1, 2, 3].should_not include(4)
"foobar".should include("bar")
"foobar".should_not include("baz")

You get a slick bit of syntactic sugar for testing the length of collections:

[1, 2, 3].should have(3).items

What if you want to specify the length of a has_many collection? "Schedule.days.should have(3).items" is admittedly quite ugly. RSpec gives us some more sweetness here as well.

schedule.should have(3).days # passes if schedule.days.length == 3

[/quote]
……不知不觉又把全文抄上了