Test Doubles, Method Stubs, Message Expectations
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3 | thingamajig_double = double('thing-a-ma-jig')
stub_thingamajig = stub('thing-a-ma-jig')
mock_thingamajig = mock('thing-a-ma-jig')
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double(),stub(),mock()都会返回一个RSpec::Mocks::Mock的实例
可以在这个实例上生成method stubs和message expectations
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13 | describe Statement do
it "logs a message on generate()" do
customer = stub('customer')
customer.stub(:name).and_return('Aslak')
logger = mock('logger')
statement = Statement.new(customer, logger)
logger.should_receive(:log).with(/Statement generated for Aslak/)
statement.generate
end
end
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这段代码中, stub('customer')和mmock('logger')分别生成了2个test double
customer.stub(:name)为customer double添加了一个method stub(打桩方法), :name为方法名 and_return('Aslak')表示:name的返回值为Aslak
logger.should_receive(:log)为logger double设置了一个对于message name() 的expectation
后面的generate()方法里, 如果logger对log()的调用失败, 则整个example会fail
否则会判断logger.should_receive(:log)后面的条件是否满足(此处为with(xxx),即log()调用是否带参数xxx)
partial stubbing, partial mocking
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25 | describe WidgetsController do
describe "PUT update with valid attributes"
it "finds the widget"
widget = Widget.new()
widget.stub(:update_attributes).and_return(true)
Widget.should_receive(:find).with("37").and_return(widget)
put :update, :id => 37
end
it "updates the widget's attributes" do
widget = Widget.new()
Widget.stub(:find).and_return(widget)
widget.should_receive(:update_attributes).and_return(true)
put :update, :id => 37
end
it "redirects to the list of widgets"
widget = Widget.new()
Widget.stub(:find).and_return(widget)
widget.stub(:update_attributes).and_return(true)
put :update, :id => 37
response.should redirect_to(widgets_path)
end
end
end
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更多关于Method Stubs
One-Line Shortcut
double(),stub(),mock()第一个参数非必填但是强烈建议有, 因为其会作为失败时的消息
此外还可以接受一个hash作为第二参数
1 | customer = double('customer', :name => 'Bryan')
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等效于
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2 | customer = double('customer')
customer.stub(:name).and_return('Bryan')
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Implementation Injection
如果一个stub method需要使用多次而且根据条件不同会有不同返回值, 可以用如下方法
多用于before()里
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8 | ages = double('ages')
ages.stub(:age_for) do |what|
if what == 'drinking'
21
elsif what == 'voting'
18
end
end
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方法链
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2 | article = double()
Article.stub_chain(:recent, :published, :authored_by).and_return(article)
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更多关于Message Expectations
执行次数
should_receive(:xxx)要求xxx()被调用且只调用一次, 如果希望调用若干次, 可采用下列方式
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5 | mock_account.should_receive(:withdraw).exactly(5).times
network_double.should_receive(:open_connection).at_most(5).times
network_double.should_receive(:open_connection).at_least(2).times
account_double.should_receive(:withdraw).once
account_double.should_receive(:deposit).twice
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如果期待方法不被调用,要使用should_not_receive
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3 | network_double.should_not_receive(:open_connection)
network_double.should_receive(:open_connection).never #不推荐
network_double.should_receive(:open_connection).exactly(0).times #不推荐
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指定期待的参数, with()
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17 | ### 指定一个参数, 且值为50
account_double.should_receive(:withdraw).with(50)
### 可以指定任意个参数
checking_account.should_receive(:transfer).with(50, savings_account)
### 第一个参数为给定值, 第二个参数为Fixnum型任意值
source_account.should_receive(:transfer).with(target_account, instance_of(Fixnum))
### 第一个参数可以为任意类型任意值
source_account.should_receive(:transfer).with(anything(), 50)
### 任意类型任意数量参数
source_account.should_receive(:transfer).with(any_args())
### 不传参数
collaborator.should_receive(:message).with(no_args())
### 参数为包含/不包含给定key/value的Hash
with(hash_including('Electric' => '123', 'Gas' => '234'))
with(hash_not_including('Electric' => '123', 'Gas' => '234'))
### 正则表达式
mock_atm.should_receive(:login).with(/.* User/)
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自定义的Argument Matchers
自定义一个类, 然后重写==(actual)方法即可
也可以添加一个description()方法以提供失败时输出的信息
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20 | class GreaterThanMatcher
def initialize(expected)
@expected = expected
end
def description
"a number greater than #{@expected}"
end
def ==(actual)
actual > @expected
end
end
def greater_than(floor)
GreaterThanMatcher.new(floor)
end
calculator.should_receive(:add).with(greater_than(37))
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Throwing or Raising
and_raise()可以不传参/一个参数(异常类或异常类实例)
and_throw()传symbol
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7 | account_double.should_receive(:withdraw).and_raise
account_double.should_receive(:withdraw).and_raise(InsufficientFunds)
the_exception = InsufficientFunds.new(:reason => :on_hold)
account_double.should_receive(:withdraw).and_raise(the_exception)
account_double.should_receive(:withdraw).and_throw(:insufficient_funds)
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按序执行
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2 | database.should_receive(:count).with('Roster', :course_id => 37).ordered
database.should_receive(:add).with(student).ordered
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只要count()在add()之前执行就会pass
