Cucumber：Hello World

巴黎的灯光下 · 发表于 2019-3-1 16:08:48

##简介##

OSChina 的链接 Cucumber

ruby 的 BDD框架，类似自然语言的DSL，适用于BDD模式和验收测试。

Book

The Rspec Book

The Cucumber Book

##Before Start##

安装，Ruby和RubyGems环境就不说了，那就剩下一句话

gem install cucumber

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##Step By Step ##

1: 描述行为

文件 "./features/greeter_says_hello.feature"

Feature: greeter says hello
Cucumber的Hello World
Scenario: 对世界打个招呼吧
Given 如果我给了你一个测试的hello
When 当我执行greet的时候
Then 我应该看到 "Hello Cucumber!"

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一个Feature 可以理解为一个功能，一个Feature由三部分组成：

标题：greeter says hello
描述：2～4行
Scenario（场景）：最后一部分

一个Feature可以有多个场景，标题和描述部分可以使用中文。一个Scenario是对feature的划分，比如一个登录的feature，scenario可以是不同角色的登录情况。（细节待补） Given When Then 是这种DSL里的关键字还有And

然后在.目录里运行一下

$ cucumber features
Feature: greeter says hello
Cucumber的Hello World
Scenario: 对世界打个招呼吧 # features/greeter_says_hello.feature:3
Given 如果我给了你一个测试的hello # features/greeter_says_hello.feature:4
When 当我执行greet的时候 # features/greeter_says_hello.feature:5
Then 我应该看到 "Hello Cucumber!" # features/greeter_says_hello.feature:6
1 scenario (1 undefined)
3 steps (3 undefined)
0m0.003s
You can implement step definitions for undefined steps with these snippets:
Given /^如该我给了你一个测试的hello$/ do
pending # express the regexp above with the code you wish you had
end
When /^当我给你一个greet的时候$/ do
pending # express the regexp above with the code you wish you had
end
Then /^我应该看到 "(.*?)"$/ do |arg1|
pending # express the regexp above with the code you wish you had
end

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2: Write a step definition in Ruby

文件：./features/step_definitions/greeter_steps.rb

(注：这里文件名没有硬性规定是根据内部的代码来查找的，greeter可以用greeter_says_hello_steps.rb)

把上面输出的内容copy进来

# -*- encoding : utf-8 -*-
Given /^如该我给了你一个测试的hello$/ do
pending # express the regexp above with the code you wish you had
end
When /^当我给你一个greet的时候$/ do
pending # express the regexp above with the code you wish you had
end
Then /^我应该看到 "(.*?)"$/ do |arg1|
pending # express the regexp above with the code you wish you had
end

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运行一下看看结果

$ cucumber features
Feature: greeter says hello
Cucumber的Hello World
Scenario: 对世界打个招呼吧 # features/greeter_says_hello.feature:3
Given 如该我给了你一个测试的hello # features/step_definitions/g_steps.rb:2
TODO (Cucumber::Pending)
./features/step_definitions/g_steps.rb:3:in `/^如该我给了你一个测试的hello$/'
features/greeter_says_hello.feature:4:in `Given 如该我给了你一个测试的hello'
When 当我给你一个greet的时候 # features/step_definitions/g_steps.rb:6
Then 我应该看到 "Hello Cucumber!" # features/step_definitions/g_steps.rb:10
1 scenario (1 pending)
3 steps (2 skipped, 1 pending)
0m0.004s

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pending指正在进行中，因为Given是正在pending，所以跳过了when和then

OK，然后写一些真正的Step

文件：./features/step_definitions/greeter_steps.rb

# -*- encoding : utf-8 -*-
Given /^如该我给了你一个测试的hello$/ do
@hello = Hello.new
end
When /^当我给你一个greet的时候$/ do
@message = @hello.greet
end
Then /^我应该看到 "(.*?)"$/ do |greeting|
@message.should == greeting
end

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这里需要注意的是then里面的 greeting代表的是前面那个描述里面的双引号扩起来的结果

3: Run and watch it fail

$ cucumber features
Feature: greeter says hello
Cucumber的Hello World
Scenario: 对世界打个招呼吧 # features/greeter_says_hello.feature:3
Given 如该我给了你一个测试的hello # features/step_definitions/g_steps.rb:7
uninitialized constant Hello (NameError)
./features/step_definitions/g_steps.rb:8:in `/^如该我给了你一个测试的hello$/'
features/greeter_says_hello.feature:4:in `Given 如该我给了你一个测试的hello'
When 当我给你一个greet的时候 # features/step_definitions/g_steps.rb:11
Then 我应该看到 "Hello Cucumber!" # features/step_definitions/g_steps.rb:15
Failing Scenarios:
cucumber features/greeter_says_hello.feature:3 # Scenario: 对世界打个招呼吧
1 scenario (1 failed)
3 steps (1 failed, 2 skipped)
0m0.003s

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4: Write code to make the step pass

文件：./features/step_definitions/greeter_steps.rb

(注：为了简单起见我就直接写到这里面了)

# -*- encoding : utf-8 -*-
class Hello
def greet
"Hello Cucumber!"
end
end
Given /^如该我给了你一个测试的hello$/ do
@hello = Hello.new
end
When /^当我给你一个greet的时候$/ do
@message = @hello.greet
end
Then /^我应该看到 "(.*?)"$/ do |greeting|
@message.should == greeting
end

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5: Run again and see the step pass

$ cucumber features
Feature: greeter says hello
Cucumber的Hello World
Scenario: 对世界打个招呼吧 # features/greeter_says_hello.feature:3
Given 如该我给了你一个测试的hello # features/step_definitions/g_steps.rb:7
When 当我给你一个greet的时候 # features/step_definitions/g_steps.rb:11
Then 我应该看到 "Hello Cucumber!" # features/step_definitions/g_steps.rb:15
1 scenario (1 passed)
3 steps (3 passed)
0m0.003s

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6: Repeat 2-5 until green like a cuke

##Summary##

从Hello World可以看出，cucumber还是很强大滴，并且输出和定义对非专业人员（需求啊 Boss啊客户啊）都很友好，如果是个不爱写文档的程序员，可以考虑用cucumber来代替一下。

BTW：虽然例子是ruby，不过cucumber还支持其他语言的，这就得看自己了。

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Cucumber：Hello World

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