使用Rspec进行行为驱动测试

使用Rspec进行行为驱动测试 ： 

require 'machine' 

describe Machine do  #Machine 是要测试的类名
    before :each do 
        @machine=Machine.new([:shopping,:checking_out])    
        @machine.events = {:checkout =>{:from => :shopping, :to => :checking_out}}
    end
    
    it "should initially have a state of the first state" do
        @machine.state.should == :shopping
    end

    it "should remember a list of valid states" do
        @machine.states.should == [:shopping, :checking_out]
    end

    it "should remember a list of events with transitions" do
        @machine.events.should == {:checkout => {:from => :shopping, :to => :checking_out}}
    end


    it "should remember a list of valid states" do
        @machine.states = [:shopping, :checking_out]
        @machine.states.should == [:shopping,:checking_out]
    end

    it "should transition to :checking_out upon #trigger(:checkout) event " do
        @machine.trigger(:checkout)
        @machine.state.should == :checking_out
    end
    
    it "should transition to :success upon #trigger(:accept_card)" do
        @machine.events = {
            :checkout =>
            {:from => :shopping,:to => :checking_out},
            
            :accept_card=> 
            {:from => :checking_out,:to => :success}
        }
        @machine.trigger(:checkout)
        @machine.state.should == :checking_out
        @machine.trigger(:accept_card)
        @machine.state.should == :success
    end


    it "should not  transition to :success upon #trigger(:accept_card)" do
        @machine.events = {
            :checkout =>
            {:from => :shopping,:to => :checking_out},
            
            :accept_card=> 
            {:from => :checking_out,:to => :success}
        }
        @machine.trigger(:accept_card)
        @machine.state.should_not == :success
    end
end

以下是ruby code:　　

class Machine

    attr_accessor :state ,:events,:states    

    def initialize(states)
        @states = states
        @state = @states[0]
    end

    def trigger(event)
        @state = events[event][:to] if state== events[event][:from]
    end

end

首先学习Rspec必须先了解测试驱动开发（TDD） 和 行为驱动开发（BDD）。

TDD:利用测试来驱动软件的设计和开发，是极限编程的重要特点，方法主要是，先写测试程序，然后再通过编码使其通过测试，他以不断的测试驱动代码的开发，这样即简化了代码又保证来软件的质量。

原理：

BDD：

RSpec 是一门专门用于描述Ruby程序的行为的ruby域指定语言。RSpec让应用程序的作者能以流畅的语言来表达他们的额设计意图。

Rspec是一系列行为的集合。这些行为具有对应的实例。

下面简要介绍Rspec 使用

1.should和预期情况

@variable.should be valid

@var.should == expected

@var.should ===expected

@var.should =~ regexp

2.结果预测

target.should be_true

target.should be_nil

target.should_not be_nil

target.should be_empty

target.should be_an_instance_of(Fixnum)

target.should be_a_kind_of(Fixnum)

target.should have_key(:key)

{:foo=>"foo"}.should have_key(:foo)

[1,2,3,4,5].should include(1)

[1,2,3,4,5].should have(5).items

3.支持自定义的断言方法

    实现步骤：

　　一：定义类 class WhatEver，

　　二：实现

　　1. initialize（expected）

　　2.matches？(actual)

　　3.failure_message

　　4.negative_failure_message

　　5.description

　　三：

　　在你的spec所包含的模组中，加入

　　def be_finished(expected)

   　　WhatEver.new(expected)

　　end

　　四：调用

　　　bob.should be_finished(x)

4.共享的行为

    1.before(:all)

    2.before(:each)

    3.after(:each)

    4.after(:all)

    5.所有预期的情况

    6.各种包含入的模组

可以通过：shared=>true 来定义共享行为

---待续

 5.RSpec的数据模拟和占位代码

---待续