Behavior-Driven Development с RSpec и Cucumber

Behavior-Driven Development
с RSpec и Cucumber
Стефан Кънев
http://skanev.com/
27.06.2009, TechCamp.eu

Tuesday, April 27, 2010

Автоматизирано тестване


Unit Tests

Test-Driven Development

Behavior-Driven Development

1. Unit test-ове
2. Test-Driven
3. Behavior-Driven
4. RSpec
5. Cucumber

class Programmer
def implement_a_change(project, change)
files = self.open_related_files(project, change)
while true
self.attempt_change(change, files)
project.run()
result = self.click_around_and_test(project)
project.stop()
break if result.successful?
end
self.commit_code(files)
self.hope_everything_went_ok()
end
end


Repetitive...


...boring...


...error-prone


Машина, която да го
прави вместо нас

Програма, която да го
прави вместо нас

Unit Test


Пишем код, който
проверява дали друг код
работи правилно.


С един бутон

Да Не

caladan:trane aquarius$ rake spec
(in /work/trane)
...............................................................
...............................................................
...............................................................
..................

Finished in 8.334414 seconds

207 examples, 0 failures


caladan:trane aquarius$ rake spec
(in /work/trane)
................................................................
................................................................
................................................................
.....F.........

1)
'User should know something' FAILED
expected: "something",
got: "nothing" (using ==)
./spec/models/user_spec.rb:32:

Finished in 8.123368 seconds

207 examples, 1 failure


I can has value?


Време


Regression testing


Документация
(развален английски + стари версии = fun)


Спецификация


Unit test-овете са
просто инструмент


Test-Driven Development е
подход към писането на
софтуер


test-ﬁrst


red/green/refactor


red/green/refactor

Възможно най-простия тест,
който проверява функцио-
налността и не минава.


red/green/refactor

Най-простата имплементация,
която кара тестът да минава
успешно.


red/green/refactor

Отстраняване на повторения,
докато кодът не стане
достатъчно качествен.


малки стъпки


Test-Driven Design


Преизползваемост


Low coupling


Добър интерфейс


scope creep


up-front design


Test-Driven Development
is not about testing


TDD ≠ QA


Опитните TDD-ри
използват процеса за
да открият поведението,
което системата трябва
да има.


Behavior-Driven
Development


BDD ≈ TDD++


"Getting the words right"


Test-Driven Behavior-Driven


Assertion Expectation


Test Method Code Example


Test Case Example Group


Domain-Driven Design


Domain Driven
Design
Eric Evans


Близки до проблемната
област думи


Разбираем за
бизнеса език


BDD = TDD + DDD
(TLA FTW)


BDD = TDD + DDD


BDD = TDD + DDD
BDD = (T + D)DD


BDD = TDD + DDD
BDD = (T + D)DD
B=T+D


BDD = TDD + DDD
BDD = (T + D)DD
B=T+D
интензитет = време + доза


Друг "синтаксис"



xUnit assert_equal 42, answer




RSpec answer.should equal(42)




RSpec answer.should equal(42)

English Answer should equal 42


assert_equal 42, result


result.should == 42


result.should == 42
assert result.nil?


result.should == 42
assert result.nil?
result.should be_nil


result.should == 42
assert result.nil?
assert result.kind_of?(User)


result.should == 42
assert result.nil?
result.should be_kind_of(User)


result.should == 42
assert result.nil?
assert [], blog.posts


result.should == 42
assert result.nil?
blog.should have(:no).posts


result.should == 42
assert result.nil?
assert 5, blog.posts.size


result.should == 42
assert result.nil?
assert 5, blog.posts.size
blog.should have(5).posts


assert_raise(InvalidRecord) do
user.save!
end


user.save!
end

lambda { user.save! }.should raise_error(InvalidRecord)


user.save!
end


assert_difference "User.count", 1 do
user.create!
end


user.save!
end


assert_difference "User.count", 1 do
user.create!
end

lambda {
user.save!
}.should change { User.count }.by(1)


class Stack < Test::Unit::TestCase
def set_up()
@stack = Stack.new
end

def test_empty
assert @stack.empty?
@stack.push 42
assert !@stack.empty?
end

def test_pop
@stack.push 42
@stack.push 5
assert_equal 5, @stack.pop
assert_equal 42, @stack.pop
asser_raise(StackEmptyError) { @stack.pop }
end
end


describe Stack do
before(:each) do
@stack = Stack.new
end

it "should be able to tell whether it is empty" do
@stack.should be_empty
@stack.push 42
@stack.should_not be_empty?
end

it "should pop the items in reverse order" do
@stack.push 42
@stack.push 5
@stack.pop.should == 5
@stack.pop.should == 42
lambda { @stack.pop }.should raise_error(StackEmptyError)
end
end


describe Stack do
context "(empty stack)" do
it "should be empty"
it "#pop should raise an exception"
end

context "(non-empty stack)" do
it "should not be empty"
it "#pop should return the top element"
it "#pop should remove the top element"
end
end


Feature: Manage posts
In order to be able to spread wisdom
the blogger
wants to be able to write about anything he wants

Scenario: Writing a new post
Given that there are no posts
And I am logged in
When I go to the new post page
And I fill "Title" with "F1rst p0st"
And I fill "Content" with "This is my first post"
And I press "Publish"
Then I should be on the front page
And I should see "This is my first post"
And there should be a new post called "F1rst p0st"


Behavior-Driven Development с RSpec и Cucumber

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