使用Rspec進行行為驅動測試

使用Rspec進行行為驅動測試 ： 

require 'machine' 

describe Machine do  #Machine 是要測試的類名
    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

首先學習Rspec必須先瞭解測試驅動開發（TDD） 和 行為驅動開發（BDD）。

TDD:利用測試來驅動軟體的設計和開發，是極限編程的重要特點，方法主要是，先寫測試程式，然後再通過編碼使其通過測試，他以不斷的測試驅動代碼的開發，這樣即簡化了代碼又保證來軟體的品質。

原理：

BDD：

RSpec 是一門專門用於描述Ruby程式的行為的ruby域指定語言。RSpec讓應用程式的作者能以流暢的語言來表達他們的額設計意圖。

Rspec是一系列行為的集合。這些行為具有對應的執行個體。

下面簡要介紹Rspec 使用

1.should和預期情況

@variable.should be valid

@var.should == expected

@var.should ===expected

@var.should =~ regexp

2.結果預測

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.支援自訂的斷言方法

    實現步驟：

　　一：定義類 class WhatEver，

　　二：實現

　　1. initialize（expected）

　　2.matches？(actual)

　　3.failure_message

　　4.negative_failure_message

　　5.description

　　三：

　　在你的spec所包含的模組中，加入

　　def be_finished(expected)

   　　WhatEver.new(expected)

　　end

　　四：調用

　　　bob.should be_finished(x)

4.共用的行為

    1.before(:all)

    2.before(:each)

    3.after(:each)

    4.after(:all)

    5.所有預期的情況

    6.各種包含入的模組

可以通過：shared=>true 來定義共用行為

---待續

 5.RSpec的資料類比和佔位代碼

---待續