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A brief introduction to the why behind TDD and an explanation on how BDD builds on that. A quick walk through of the ruby BDD framework, rspec.
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The why behind TDD/BDD and the how with RSpec
$ whois benmabey.com
Registrant: Ben Mabey
Programming Ruby Since: may-2006BDDing it Since: may-2007Employer: Alliance Health Networks
$ whois benmabey.com
Registrant: Ben Mabey
Programming Ruby Since: may-2006BDDing it Since: may-2007Employer: Alliance Health Networks
$ whois benmabey.com
Why do we test?
Why do we test?
Confidence. Verification that our system behaves as it is suppose to.
Why do we test?
Confidence. Verification that our system behaves as it is suppose to.
This can be done manually or can be automated. Automation is clearly our friend...
Why automation?
Why automation?
Confidence. Regression Tests!
Why automation?
Confidence. Regression Tests!
Refactoring - Shortened feedback loop makes improving our design much easier and less painful.
Riddle me this...Which tests instill more confidence of a
system’s behavior in you?(Assume they have the same coverage.)
Riddle me this...Which tests instill more confidence of a
system’s behavior in you?(Assume they have the same coverage.)
Tests written after functionality is added.
Riddle me this...Which tests instill more confidence of a
system’s behavior in you?(Assume they have the same coverage.)
Tests written after functionality is added.
Tests written before functionality is added.
Riddle me this...Which tests instill more confidence of a
system’s behavior in you?(Assume they have the same coverage.)
Tests written after functionality is added.
Neither. Both provide equal confidence.
Tests written before functionality is added.
Why test first then?
Why test first then?Most of us aren’t disciplined enough to test last. Once we have manually tested the system taking the time to write an automated test seems like a pain.
Why test first then?Most of us aren’t disciplined enough to test last. Once we have manually tested the system taking the time to write an automated test seems like a pain.
Code that isn’t written with tests in mind tends to be very difficult to test without refactoring it first.
Clear up a common misconception...
Clear up a common misconception...
TDD != writing tests first
Clear up a common misconception...
TDD != writing tests first
TDD =~ writing test first.. but
Clear up a common misconception...
TDD != writing tests first
TDD =~ writing test first.. but
TDD isn’t about testing...
Clear up a common misconception...
TDD != writing tests first
TDD =~ writing test first.. but
TDD isn’t about testing...
TDD is about DESIGN
Clear up a common misconception...
TDD != writing tests first
TDD =~ writing test first.. but
TDD isn’t about testing...
TDD is about DESIGN
RED -> GREEN -> REFACTOR
Design is aPROCESS
not aPHASE
The TDD cycle of RED->GREEN->REFACTOR enablesyou to iterate over your design constantly by
removing duplication (refactoring). Testing units in isolation allows you to achieve high cohesion and
loose coupling regularly.
Side benefits of TDD are...
Side benefits of TDD are...Verification of behavior.
Side benefits of TDD are...Verification of behavior.
Documentation.
Side benefits of TDD are...Verification of behavior.
Documentation.“The act of writing a unit test is more an act of design than of verification. It is also more an act of documentation than of verification. The act of writing a unit test closes a remarkable number of feedback loops, the least of which is the one pertaining to verification of function” -”Uncle” Bob Martin
Riddle me that...Which tests instill more confidence of a
system’s design and long term maintainability?
Riddle me that...Which tests instill more confidence of a
system’s design and long term maintainability?
Tests written after functionality is added.
Riddle me that...Which tests instill more confidence of a
system’s design and long term maintainability?
Tests written after functionality is added.
Tests written with good TDD skillz.
Riddle me that...Which tests instill more confidence of a
system’s design and long term maintainability?
Tests written after functionality is added.
It depends. Are you Bob Martin or Jim Coplien? :p
Tests written with good TDD skillz.
Riddle me that...Which tests instill more confidence of a
system’s design and long term maintainability?
Tests written after functionality is added.
It depends. Are you Bob Martin or Jim Coplien? :p
Tests written with good TDD skillz.
I’m with Uncle Bob on this one *when* TDD is done right...
So why BDD?
So why BDD?
Doing TDD right andunderstanding what it is
all about is hard.
So why BDD?Introducing BDD - Dan Northhttp://dannorth.net/introducing-bdd
So why BDD?
“I had a problem. While using and teaching agile practices like test-driven development (TDD) on
projects in different environments, I kept coming across the same confusion and misunderstandings.
Programmers wanted to know where to start, what to test and what not to test, how much to test in one go, what to call their tests, and how to understand
why a test fails.”
Introducing BDD - Dan Northhttp://dannorth.net/introducing-bdd
So why BDD?
“The deeper I got into TDD, the more I felt that my own journey had been less of a wax-on, wax-off process of gradual mastery than a series of blind
alleys. I remember thinking ‘If only someone had told me that!’ far more often than I thought ‘Wow, a door has opened.’ I decided it must be possible to present TDD in a way that gets straight to the good stuff
and avoids all the pitfalls.”
Introducing BDD - Dan Northhttp://dannorth.net/introducing-bdd
So why BDD?
“My response is behaviour-driven development (BDD). It has evolved out of established agile practices and
is designed to make them more accessible and effective for teams new to agile software delivery. Over time, BDD has grown to encompass the wider picture of agile analysis and automated acceptance
testing.”
Introducing BDD - Dan Northhttp://dannorth.net/introducing-bdd
BDD with RSpec
BDD with RSpecAcceptance Test Driven Testing
BDD with RSpecAcceptance Test Driven Testing
Business Analysis
BDD with RSpecAcceptance Test Driven Testing
Business Analysis
Executable Acceptance Criteria
BDD with RSpecAcceptance Test Driven Testing
Business Analysis
Executable Acceptance Criteria
Test Driven Development with a vocabulary that focuses on behavior not tests.
BDD with RSpecAcceptance Test Driven Testing
Business Analysis
Executable Acceptance Criteria
Test Driven Development with a vocabulary that focuses on behavior not tests.
Story Framework
BDD with RSpecAcceptance Test Driven Testing
Business Analysis
Executable Acceptance Criteria
Test Driven Development with a vocabulary that focuses on behavior not tests.
Story Framework
As a.. I want.. So that..
BDD with RSpecAcceptance Test Driven Testing
Business Analysis
Executable Acceptance Criteria
Test Driven Development with a vocabulary that focuses on behavior not tests.
Story Framework
As a.. I want.. So that..
Scenarios - Ruby or plain text
BDD with RSpecAcceptance Test Driven Testing
Business Analysis
Executable Acceptance Criteria
Test Driven Development with a vocabulary that focuses on behavior not tests.
Story Framework
As a.. I want.. So that..
Scenarios - Ruby or plain text
Example Framework - DSL for specifying behavior
So... how does this help?Introducing BDD - Dan Northhttp://dannorth.net/introducing-bdd
So... how does this help?
“I had a problem. While using and teaching agile practices like test-driven development (TDD) on
projects in different environments, I kept coming across the same confusion and misunderstandings.
Programmers wanted to know where to start, what to test and what not to test, how much to test in one go, what to call their tests, and how to understand
why a test fails.”
Introducing BDD - Dan Northhttp://dannorth.net/introducing-bdd
So... how does this help?where to start
what to test
what not to test
how much to test in one go
what to call their tests
understand why a test fails
idea taken from http://www.slideshare.net/Robbert/bdd-rspec
outside-in
So... how does this help?where to start
what to test
what not to test
how much to test in one go
what to call their tests
understand why a test fails
idea taken from http://www.slideshare.net/Robbert/bdd-rspec
outside-in
user stories
So... how does this help?where to start
what to test
what not to test
how much to test in one go
what to call their tests
understand why a test fails
idea taken from http://www.slideshare.net/Robbert/bdd-rspec
outside-in
user stories
anything else
So... how does this help?where to start
what to test
what not to test
how much to test in one go
what to call their tests
understand why a test fails
idea taken from http://www.slideshare.net/Robbert/bdd-rspec
Story Framework
outside-in
user stories
anything else
So... how does this help?where to start
what to test
what not to test
how much to test in one go
what to call their tests
understand why a test fails
idea taken from http://www.slideshare.net/Robbert/bdd-rspec
What’s in a story?http://dannorth.net/whats-in-a-story - Dan North
What’s in a story?http://dannorth.net/whats-in-a-story - Dan North
Story: (one line describing the story)
What’s in a story?http://dannorth.net/whats-in-a-story - Dan North
Story: (one line describing the story)
As a [role]
What’s in a story?http://dannorth.net/whats-in-a-story - Dan North
Story: (one line describing the story)
As a [role]I want to [some action]
What’s in a story?http://dannorth.net/whats-in-a-story - Dan North
Story: (one line describing the story)
As a [role]I want to [some action]So that [business value!]
What’s in a story?http://dannorth.net/whats-in-a-story - Dan North
What’s in a story?http://dannorth.net/whats-in-a-story - Dan North
Acceptance Criteria as Scenarios
What’s in a story?http://dannorth.net/whats-in-a-story - Dan North
Acceptance Criteria as ScenariosScenario: title
What’s in a story?http://dannorth.net/whats-in-a-story - Dan North
Acceptance Criteria as ScenariosScenario: titleGiven [some context]
What’s in a story?http://dannorth.net/whats-in-a-story - Dan North
Acceptance Criteria as ScenariosScenario: titleGiven [some context]And [additional context]
What’s in a story?http://dannorth.net/whats-in-a-story - Dan North
Acceptance Criteria as ScenariosScenario: titleGiven [some context]And [additional context]When [event]
What’s in a story?http://dannorth.net/whats-in-a-story - Dan North
Acceptance Criteria as ScenariosScenario: titleGiven [some context]And [additional context]When [event]Then [outcome]
What’s in a story?http://dannorth.net/whats-in-a-story - Dan North
Acceptance Criteria as ScenariosScenario: titleGiven [some context]And [additional context]When [event]Then [outcome]
Scenario: another variant
What’s in a story?http://dannorth.net/whats-in-a-story - Dan North
Acceptance Criteria as ScenariosScenario: titleGiven [some context]And [additional context]When [event]Then [outcome]
Scenario: another variantGiven...
Story Time
Story Framework
outside-in
user stories
anything else
So... how does this help?where to start
what to test
what not to test
how much to test in one go
what to call their tests
understand why a test fails
idea taken from http://www.slideshare.net/Robbert/bdd-rspec
Story Framework
outside-in
user stories
anything else
So... how does this help?where to start
what to test
what not to test
how much to test in one go
what to call their tests
understand why a test fails
idea taken from http://www.slideshare.net/Robbert/bdd-rspec
very little-focused
Story Framework
outside-in
user stories
anything else
So... how does this help?where to start
what to test
what not to test
how much to test in one go
what to call their tests
understand why a test fails
idea taken from http://www.slideshare.net/Robbert/bdd-rspec
very little-focused
sentence template
Story Framework
outside-in
user stories
anything else
So... how does this help?where to start
what to test
what not to test
how much to test in one go
what to call their tests
understand why a test fails
idea taken from http://www.slideshare.net/Robbert/bdd-rspec
very little-focused
sentence template
documentation
Example Framework
Story Framework
outside-in
user stories
anything else
So... how does this help?where to start
what to test
what not to test
how much to test in one go
what to call their tests
understand why a test fails
idea taken from http://www.slideshare.net/Robbert/bdd-rspec
very little-focused
sentence template
documentation
Test::Unit to RSpec
Test::Unit to RSpec
class DogTest
Test::Unit to RSpec
class DogTest describe Dog
Test::Unit to RSpec
class DogTest describe Dog
def test_bark
Test::Unit to RSpec
class DogTest describe Dog
def test_bark it “should bark”
Test::Unit to RSpec
class DogTest describe Dog
def test_bark it “should bark”
assert_xxx
Test::Unit to RSpec
class DogTest describe Dog
def test_bark it “should bark”
assert_xxx object.should be_xxx
Test::Unit to RSpec
class DogTest describe Dog
def test_bark it “should bark”
assert_xxx object.should be_xxx
def setup
Test::Unit to RSpec
class DogTest describe Dog
def test_bark it “should bark”
assert_xxx object.should be_xxx
def setup before(:each) {}
Test::Unit to RSpec
class DogTest describe Dog
def test_bark it “should bark”
assert_xxx object.should be_xxx
def setup before(:each) {}
def teardown
Test::Unit to RSpec
class DogTest describe Dog
def test_bark it “should bark”
assert_xxx object.should be_xxx
def setup before(:each) {}
def teardown after(:each) {}
Matchersa.should == b, a.should equal(b), a.should eql(b)
a.should_not ....
a.should_be nil
a.should be_happy # calls a.happy?
a.should match(/regex/), a.should =~ /regex/)
lambda { a.blah }.should raise_error
http://rspec.info/rdoc/classes/Spec/Matchers.html
Mocks
MocksInteraction-Based Testing
http://www.martinfowler.com/articles/mocksArentStubs.html
http://nat.truemesh.com/archives/000342.html
MocksInteraction-Based Testing
http://www.martinfowler.com/articles/mocksArentStubs.html
http://nat.truemesh.com/archives/000342.html
Not concerned about the state. Just how it interacts with other objects.
MocksInteraction-Based Testing
http://www.martinfowler.com/articles/mocksArentStubs.html
http://nat.truemesh.com/archives/000342.html
Not concerned about the state. Just how it interacts with other objects.
Helps drive design.
MocksInteraction-Based Testing
http://www.martinfowler.com/articles/mocksArentStubs.html
http://nat.truemesh.com/archives/000342.html
Not concerned about the state. Just how it interacts with other objects.
Helps drive design.
Allows you to test collaborators in isolation.
MocksInteraction-Based Testing
http://www.martinfowler.com/articles/mocksArentStubs.html
http://nat.truemesh.com/archives/000342.html
Not concerned about the state. Just how it interacts with other objects.
Helps drive design.
Allows you to test collaborators in isolation.
Need stories to make sure it all “works”.
MocksInteraction-Based Testing
http://www.martinfowler.com/articles/mocksArentStubs.html
http://nat.truemesh.com/archives/000342.html
Not concerned about the state. Just how it interacts with other objects.
Helps drive design.
Allows you to test collaborators in isolation.
Need stories to make sure it all “works”.
Mocks
RSpec Built in Mocking framework
Mocha
FlexMock
Example Time
TipsOne Expectation per test
Write Expectation first
Isolation
Detect Code smells in setup with stubs
ExampleGroup level shared behavior helpers
Blocks are your friend
spec, autotest, drb server, RSpactor
Continuous Integration - CC.rb
Resourceshttp://rspec.info/
http://www.benmabey.com/2008/02/04/rspec-plain-text-stories-webrat-chunky-bacon/
http://blog.davidchelimsky.net/
Recommended Reading
Test Driven Development: By Example, by Kent Beck
Test-Driven Development: A Practical Guide, by David Astels
Domain-Driven Design: Tackling Complexity in the Heart of Software by Eric Evans
Refactoring: Improving the Design of Existing Code by Martin Fowler
Working Effectively with Legacy Code by Michael Feathers
Agile Software Development, Principles, Patterns, and Practices by Bob Martin
![[Tech talk] testing for the skeptical developer (tdd, bdd & other)](https://img.pdfslide.us/doc/110x75/58746dd31a28abab198b8c35/tech-talk-testing-for-the-skeptical-developer-tdd-bdd-other.jpg)
