Test-Driven Development + Refactoring

Test-Driven Development

Refactoring

Стефан Къневhttp://skanev.com/@skanev

WebTech25 Април 2010Велико Търново

Sunday, April 25, 2010

за мен

програмистSunday, April 25, 2010

♥Sunday, April 25, 2010

първи unit testпърви работен ден

презентационни умения

3Sunday, April 25, 2010

говоря бързо

210Sunday, April 25, 2010

Аз ползвамVisual Source Safe

test-‐driven developmentrefactoring

extreme programming

test-‐driven developmentrefactoring

УебТех, миналата година

Моя браузър е Гугъл, бабиното.

Правя Test-Driven Development.

Пиша тестове

конкретни практики

План

1. Какво е test-‐driven?

План

2. Малка демонстрация (видео!)

План

3. TDD в реалния свят

План

4. Въпроси & дискусия

@skanev Мога да прилагам test-‐drivendevelopment извън програмирането?Например за да готвя обяд? #p2pvt

План

refactor |rēˈfaktər|verb

improving the design of codewithout changing its behavior

не добавяте функционалност

не добавяте функционалностподобрявете код

не добавяте функционалностподобрявете кодмалки стъпки

защо пишем тестове?

накратко, за да спестимусилия в дългосрочен

план

test-drivendevelopment

automatedtesting

Инструмент

Автоматизирани тестове

Подход

Test-DrivenDevelopment

Test-Driven Development

“Test-‐Driven Development is not about testing”

— Dan North

дизайн

Test-‐Driven Design

на практика

Добавяте тест1 ...за несъществуващ код

Пишете код2 ...колкото тестът да мине

Правите подобрения3 ...докато премахнете повторенията

• Тествате кода, който бихте искали да имате

• Няма да се компилира (липсващи методи/класове)

• Пускате го и гледате как се проваля

• Имате червен тест проверяващ функционалността

• Добавяте достатъчно код за да мине теста

• Нито ред повече

• Най-простото решение, което ви хрумва

• Имате работещ код и зелен тест, който го потвърждава

• Не добавяте функционалност

• Подобрявате кода/дизайна

• Премахвате повторенията

• На всяка стъпка пускате теста

1 2 3TDD =

Discla

1 2 3Кодът, който искате да имате

describe "Message" do it "should support initialization" do message = Message.new('fry@foo.bg', 'bender@foo.bg', 'Hi!') message.from.should == 'fry@foo.bg' message.to.should == 'bender@foo.bg' message.title.should == 'Hi!' endend

1 2 3Кодът, който искате да имате

describe "Message" do it "should support initialization" do message = Message.new('fry@foo.bg', 'bender@foo.bg', 'Hi!') message.from.should == 'fry@foo.bg' message.to.should == 'bender@foo.bg' message.title.should == 'Hi!' endend

1)NameError in 'Message should support initialization'uninitialized constant Message/work/message/spec/message_spec.rb:5:

Finished in 0.009336 seconds

1 example, 1 failure

1 2 3Най-‐простата имплементация

class Message attr_reader :from, :to, :title def initialize(from, to, title) @from = from @to = to @title = title endend

1 example, 0 failures

1 2 3Пас

Всичко изглежда ок, няма нужда от рефакториране

1 2 3Изразявате новата функционалност в тест

describe 'Message' do # ... it "should validate 'from'" do # bacon.should be_valid ⇔ assert bacon.valid? Message.new('fry@foo.bg', 'bender@foo.bg', 'Hi!').should be_valid Message.new('foo.bg', 'bender@foo.bg', 'Hi!').should_not be_valid Message.new('fry@foo', 'bender@foo.bg', 'Hi!').should_not be_valid endend

1 2 3Изразявате новата функционалност в тест

describe 'Message' do # ... it "should validate 'from'" do # bacon.should be_valid ⇔ assert bacon.valid? Message.new('fry@foo.bg', 'bender@foo.bg', 'Hi!').should be_valid Message.new('foo.bg', 'bender@foo.bg', 'Hi!').should_not be_valid Message.new('fry@foo', 'bender@foo.bg', 'Hi!').should_not be_valid endend

1)NoMethodError in 'Message should validate 'from''undefined method `valid?' for #<Message:0x100327e08>/work/message/spec/message_spec.rb:13:

2 examples, 1 failure

1 2 3Прост регулярен израз

class Message attr_reader :from, :to, :title def initialize(from, to, title) @from = from @to = to @title = title end def valid? @from =~ /^[a-z]+@[a-z]+(\.[a-z]+)+$/ endend

1 2 3Прост регулярен израз

2 examples, 0 failures

1 2 3Отново пас

Все още всичко е ОК

1 2 3Отново, почвате с тест преди кода

describe 'Message' do # ... it "should validate 'to'" do Message.new('fry@foo.bg', 'bender@foo.bg', 'Hi!').should be_valid Message.new('fry@foo.bg', 'bender', 'Hi!').should_not be_valid Message.new('fry@foo.bg', 'bender@foo', 'Hi!').should_not be_valid endend

1 2 3Отново, почвате с тест преди кода

describe 'Message' do # ... it "should validate 'to'" do Message.new('fry@foo.bg', 'bender@foo.bg', 'Hi!').should be_valid Message.new('fry@foo.bg', 'bender', 'Hi!').should_not be_valid Message.new('fry@foo.bg', 'bender@foo', 'Hi!').should_not be_valid endend

1)'Message should validate 'to'' FAILEDexpected valid? to return false, got 0/work/message/spec/message_spec.rb:20:

3 examples, 1 failure

class Message attr_reader :from, :to, :title def initialize(from, to, title) @from = from @to = to @title = title end def valid? @from =~ /^[a-z]+@[a-z]+(\.[a-z]+)+$/ and @to =~ /^[a-z]+@[a-z]+(\.[a-z]+)+$/ endend

1 2 3Повторение

class Message attr_reader :from, :to, :title def initialize(from, to, title) @from = from @to = to @title = title end def valid? @from =~ /^[a-z]+@[a-z]+(\.[a-z]+)+$/ and @to =~ /^[a-z]+@[a-z]+(\.[a-z]+)+$/ end private def email_valid?(address) address =~ /^[a-z]+@[a-z]+(\.[a-z]+)+$/ endend

1 2 3Малки стъпки

class Message attr_reader :from, :to, :title def initialize(from, to, title) @from = from @to = to @title = title end def valid? @from =~ /^[a-z]+@[a-z]+(\.[a-z]+)+$/ and @to =~ /^[a-z]+@[a-z]+(\.[a-z]+)+$/ end private def email_valid?(address) address =~ /^[a-z]+@[a-z]+(\.[a-z]+)+$/ endend

1 2 3Малки стъпки

class Message attr_reader :from, :to, :title def initialize(from, to, title) @from = from @to = to @title = title end def valid? email_valid?(@from) and @to =~ /^[a-z]+@[a-z]+(\.[a-z]+)+$/ end private def email_valid?(address) address =~ /^[a-z]+@[a-z]+(\.[a-z]+)+$/ endend

1 2 3Ама наистина малки стъпки

class Message attr_reader :from, :to, :title def initialize(from, to, title) @from = from @to = to @title = title end def valid? email_valid?(@from) and @to =~ /^[a-z]+@[a-z]+(\.[a-z]+)+$/ end private def email_valid?(address) address =~ /^[a-z]+@[a-z]+(\.[a-z]+)+$/ endend

1 2 3Ама наистина малки стъпки

class Message attr_reader :from, :to, :title def initialize(from, to, title) @from = from @to = to @title = title end def valid? email_valid?(@from) and email_valid?(@to) end private def email_valid?(address) address =~ /^[a-z]+@[a-z]+(\.[a-z]+)+$/ endend

1 2 3Готово

class Message attr_reader :from, :to, :title def initialize(from, to, title) @from = from @to = to @title = title end def valid? email_valid?(@from) and email_valid?(@to) end private def email_valid?(address) address =~ /^[a-z]+@[a-z]+(\.[a-z]+)+$/ endend

1 2 3Готово

пример за интерфейса

принуждава ви да измислите дизайн

дизайнът е основан наобратна връзка, а не

на спекулация

гарантира ви че имате тест

тестовете се забравят

false positive

гарантира, чекодът е тестваем

sans debugging

Scope creep

Y.A.G.N.I.Y! ain’t gonna need it

Защо?

•обратна връзка

•мързел

•тестваем код

•debugging

•scope creep

План

EPIC FAIL

План

Терминологията е оплетена

червеножълтозеленосиньо

червеносиньожълтозеленосиньо

РитъмSunday, April 25, 2010

ДисциплинаSunday, April 25, 2010

тестовете трябва да правятприложението по-‐лесно за

поддръжка

лошото прилагане натестове може да го направипо-‐трудно за поддържане

тестовете трябва да правятприложението по-‐лесно за

поддръжка

лошото прилагане натестове може да го направипо-‐трудно за поддържане

Голям

проблем

тестовете са примеркак се работи с

кодът ви

example-‐driven development

assert ➡ expectationtest method ➡ exampletest case ➡ example group

Тестовете като документацияSunday, April 25, 2010

“Test-‐Driven Development is not about testing”

— Dan North

user stories

CucumberFeature: User accounts Scenario: Changing your password Given my password is "zero cool" And I just logged in When I go to the settings page And I fill in "Password" with "secret" And I fill in "Password confirmation" with "secret" And I press "Save password" Then my password should be "secret"

CucumberFeature: User accounts ... Scenario: Confirmation fail on password change Given my password is "zero cool" And I just logged in When I go to the settings page And I fill in "Password" with "secret" But I fill in "Password confirmation" with "tetris" And I press "Save password" Then I should see "Password and confirmation didn't match" And my password should be "zero cool"

behavior-‐driven development

прилага идеите на TDDвърху feature-‐ите* на

приложението

* чуждиците не са куул

greenrefactor

Cucumber

continuous testing

ресурси

Software Craftsmanship Bulgaria

http://groups.google.com/group/software_craftsmanship

just google it

План

Test-Driven Development + Refactoring

Technology

A Model-driven Approach to Refactoring

Refactoring and its role in Test-Driven Development

Refactoring and its role in Test-Driven Development Miguel J. T. Pessoa Monteiro Escola Superior de Tecnologia de Castelo Branco

Kayak: Safe Semantic Refactoring to Java Streams · driven refactoring, which enables much more sophisticated refac-toring schemata. As an exemplar of this broader idea, we present

Model-Driven Java Code Refactoring...Model-Driven Java Code Refactoring 377 In Section 6, the evaluation of the extensibility and the modification possibilities offered by our approach

Test Driven Development and Refactoring

Test-Driven Development vs. Test-After …Test-after (TAD) vs. Test-first (TDD) • Allows some refactoring • Coverage levels up to ~75% • No direct design impact • Can reduce

Refactoring Classes Lesson Six: Classes. Refactoring Classes Class Decomposition is difficult. Several Techniques exist: Behavioral Driven Design[Kowal]

Refactoring legacy code driven by tests - ITA

Refactoring Legacy Web Forms for Test Automation

TDD FOR BEGINNERS€¦ · •Test-Driven Development •Code quality •High maintainability •Refactoring PRACTICAL DETAILS!! Duration: 1 day-long TDD in JavaScript Prerequisites:

Program Refactoring, Program Synthesis, and Model-Driven ... · program refactoring, program synthesis, and model-driven development, all of which deal with program structure and

Test Driven Refactoring by Andreas Thies. XP 2004 - Test Driven Refactoring2 Overview Refactoring Bad Smells Unit Tests Unit Tests and Refactoring Special

Mutation Testing as a Safety Net for Test Code Refactoring · Mutation Testing as a Safety Net for Test Code Refactoring Ali Parsai Alessandro Murgia Quinten D. Soetens Serge Demeyer

Test Driven Development and Refactoring (plus an eclectic ... · Test-Driven Development: Key Ideas Tests get written first (not postponed) Stub in method, then write tests for method

Renaissance Software · Course: Test-Driven Development and Refactoring in C++ Dates: 12/10 - 12/12/2008 Instructor: James Grenning Comments on the course content: Comments on the

Refactoring to Rich Internet Applications. A Model-Driven Approachicwe2008.webengineering.org/program/proceedings/isbn978... · 2009-10-11 · Refactoring to Rich Internet Applications

BizSpark SF Lightning Talk: "Refactoring and Test-Driven Development" by Mathias Brandewinder

Refactoring guided by design principles driven by technical debt

How do you Learn New Skills? - GOTO Conference · ! using IDE shortcuts ! Pair Programming ! Test Driven Development ! Designing good Test Cases ! Refactoring ! Working incrementally,