Do you TDD or BDD? Why not both? Come learn the "Double Loop" workflow and discover how you can use both Behavior Driven Development and Test Driven Development to write well designed, tested and documented code. Double Loop works for lone engineers, small teams or entire product departments. I'll cover the steps you'll take in the workflow as each role as well as tools for executing Double Loop

1. Double Loop
TDD & BDD Done Right!
@jessicamauerhan | #ATO2016

2. @jessicamauerhan
Senior Software Engineer
TDD/BDD Expert
jessicamauerhan@gmail.com
jmauerhan.wordpress.com

3. @jessicamauerhan | #ATO2016
What is
Test Driven
Development?
Test Driven Development is a process in
which you first write a failing unit test,
execute that test, write just enough code to
make the test pass, then refactor that code
for improvements.

4. @jessicamauerhan | #ATO2016
Benefits of Test Driven Development
● Guides you towards creating a
well-abstracted and highly
modular system.
● Makes the software easier to
change, maintain and
understand.
● Promotes using design patterns,
refactoring, and helps prevent
scope creep.
● Complete test coverage
● Preventing and identifying
regressions and mistakes with
automated tests
● Executable documentation.
Primary Secondary

5. @jessicamauerhan | #ATO2016
What is
Behavior
Driven
Development?
Behaviour-driven development is an “outside-in”
methodology. It starts at the outside by identifying
business outcomes, and then drills down into the
feature set that will achieve those outcomes. Each
feature is captured as a “story”, which defines the
scope of the feature along with its acceptance
criteria.
Dan North, “What’s in a Story”
http://dannorth.net/whats-in-a-story
It’s the idea that you start by writing
human-readable sentences that describe a
feature of your application and how it should
work, and only then implement this behavior in
software.
Behat Documentation
http://docs.behat.org/en/v2.5

6. @jessicamauerhan | #ATO2016
Why Practice BDD?
● Well Designed Code
● Automated Testing
● Implementation
● UI Testing
BDD Is Not About...
● Communication
● Collaboration
● Documentation
● Preventing Regressions
BDD Is About...

7. @jessicamauerhan | #ATO2016
Why Practice
Behavior Driven
Development?
“You can turn an idea for a
requirement into implemented,
tested, production-ready code
simply and effectively, as long as the
requirement is specific enough that
everyone knows what’s going on.”
Dan North, “What’s in a Story”
http://dannorth.net/whats-in-a-story

8. @jessicamauerhan | #ATO2016
Accuracy
Unit Tests describe accuracy
of code and prescribe
maintainable code
Suitability
Behavior Tests describe
suitability of software's
features for the end user

9. @jessicamauerhan | #ATO2016
Testing Pyramid
Maintenance
Coverage
Fragility
Duration
Cost
Number of Tests
Unit Tests
Behavior Tests
System Tests
(performance)
GUI
Tests
Unit
Behavior
System
GUI
Manual QA
Testing Ice Cream Cone

10. @jessicamauerhan | #ATO2016
The Vicious Cycle of the Testing Ice Cream Cone
Unit
Behavior
System
GUI
Manual QA
Non Testable
Code
More Expensive
Tests
Developers Don't
Run Tests
More Bugs
Developers Don't
Write Unit Tests

11. Add
Behavior
Test
Add
Unit
Test
Run Unit
Test
Add/Edit
Some Code
Refactor
Run All
Unit Tests
Run All
Behavior
Tests
Pass* Fail
Fail
Pass
Run
Behavior
Test Pass*
Fail
Fail Pass
Revert Changes
@jessicamauerhan | #ATO2016
Double Loop: TDD & BDD Done Right!
Feature
Done?
NoYes
* A test that passes the first time
before code has been written means
the test is inaccurate or poorly
written, not added to the test suite,
or the code/feature already exists.

12. Add
Behavior
Test

13. @jessicamauerhan | #ATO2016
Parts of
a Behavior Test
● Feature: Gherkin
● Test Code
● BDD Framework /
Test Runner

14. @jessicamauerhan | #ATO2016
Gherkin
● Business Readable, Domain
Specific Language
● Living Documentation / User
Manual
● User Story with Narrative
● Contains at least one
Scenario: Acceptance Criteria

15. @jessicamauerhan | #ATO2016
● Narrative
○ As a [role]
I want [feature]
So that [benefit / business reason]
○ Use “5 Whys” to determine narrative
As an Account Holder
I want to withdraw cash from an ATM
So that I can get money when the bank is closed
Scenario: Account has sufficient funds
Given the account has a balance
And the card is valid
And the machine contains at least the amount of my balance
When I request an amount less than or equal to my balance
Then the ATM should dispense that amount
And the amount should be subtracted from my account balance
And the card should be returned
Scenario: Account has insufficient funds
Given the account has a balance
And the card is valid
And the machine contains at least the amount of my balance
When I request an amount greater than my balance
Then the ATM should not dispense any money
And the ATM should say there are insufficient funds
And my account balance should not change
And the card should be returned
● Feature: Short, Descriptive, Action
● Acceptance Criteria: Scenarios
○ Given: Exact Context
○ When: Action/Event
○ Then: Outcomes
○ And/But: More of the same...
●
Feature: Account Holder Withdraws Cash

16. @jessicamauerhan | #ATO2016
As a user viewing a broadcast page before the broadcast starts
I want to see a countdown timer
So that I can know how long until the broadcast actually starts
Scenario: View Countdown before Broadcast
Given I view the “Future Broadcast” broadcast
Then I should see "Future Broadcast" on the page
And I should see "Future Broadcast Author" on the page
And I should see "This broadcast begins at 6:00 pm EST" on the
page
And I should see a countdown timer
Feature: View Countdown before Broadcast
Process
● Author describes Feature with
implementation specific
example
● Developer adds fixture data
Issues
● Test only works before 6pm
● What is the intent?
● Confusion for business users

17. @jessicamauerhan | #ATO2016
As a user viewing a broadcast page before the broadcast starts
I want to see a countdown timer
So that I can know how long until the broadcast actually starts
Scenario: View Countdown before Broadcast
Given there is a broadcast scheduled for the future
When I view that broadcast’s page
Then I should see the broadcast title
And I should see the broadcast author’s name
And I should see "This broadcast begins at" followed by the start
time in EST
And I should see a countdown timer
Feature: View Countdown before Broadcast Changes
● Given now explains exact
context
● Test is no longer
time-dependent
● Intent - not implementation
Why?
● Overall understanding
● Communication value
● Help identify poorly written
code

18. @jessicamauerhan | #ATO2016
Feature: Customer Views Product and Services Catalog
As a customer
I want to view the product catalog
So that I can browse products and services
Scenario: Customer views Product Catalog
Given I view the catalog
When I select a state from the list of states
Then I should see the list of products for sale
Scenario: Display Local Services in Product Catalog
Given the company has a regional office in a state
When I view the catalog
And I select that state from the list of states
Then I should see the list of services offered
echo '<h1>Products</h1>';
foreach ($products AS $product) {
echo '<p>' . $product->getName() . '</p>';
}
echo '<h1>Services</h1>';
foreach ($services AS $service) {
echo '<p>' . $service->getName() . '</p>';
}
Scenario: Don’t Display Local Services in Product Catalog For States
With No Regional Office
Given the company does not have a regional office in a
state
When I view the catalog
And I select that state from the list of states
Then I should not see a list of services offered

19. @jessicamauerhan | #ATO2016
Feature: Customer Views Product and Services Catalog
As a customer
I want to view the product catalog
So that I can browse products and services
Scenario: Customer views Product Catalog
Given I view the catalog
When I select a state from the list of states
Then I should see the list of products for sale
Scenario: Display Local Services in Product Catalog
Given the company has a regional office in a state
When I view the catalog
And I select that state from the list of states
Then I should see the list of services offered
Scenario: Don’t Display Local Services in Product Catalog For States
With No Regional Office
Given the company does not have a regional office in a
state
When I view the catalog
And I select that state from the list of states
Then I should not see a list of services offered
echo '<h1>Products</h1>';
foreach ($products AS $product) {
echo '<p>' . $product->getName() . '</p>';
}
if(count($services) > 0) {
echo '<h1>Services</h1>';
foreach ($services AS $service) {
echo '<p>' . $service->getName() . '</p>';
}
}

20. @jessicamauerhan | #ATO2016
Writing Great Features
● Exact Context
● Independent Scenarios &
Features
● Intention, not Implementation
● Defined Narrative
● All Paths Explored
Feature “Smells”
● Time Dependency
● Interdependency
● Multi-Scenario Scenarios
● Missing Scenarios
● Overuse of Variables
● Examples of Behavior
(Implementation, not Intention)

21. @jessicamauerhan | #ATO2016
Parts of
a Behavior Test
● Feature: Gherkin
● Test Code
● BDD Framework /
Test Runner

22. @jessicamauerhan | #ATO2016
BDD Frameworks / Test Runners
● Java - JBehave, Cucumber and more
● Ruby - Cucumber
● PHP - Behat
● JavaScript - cucumber.js, jasmine
● ...

23. @jessicamauerhan | #ATO2016
Scenario: Customer views
Product Catalog
Given I view the catalog
When I select a state from the list
of states
Then I should see the list of
products for sale
Behat Code/**
* @Given I view the catalog
*/
public function iViewTheCatalog()
{
$this->visit('catalog');
}
/**
* @When I select a state from the list of states
*/
public function iSelectAStateFromTheListOfStates()
{
$this->selectOption('states', rand(1, 52));
}
/**
* @Then I should see the list of products for sale
*/
public function iShouldSeeTheListOfProductsForSale()
{
$productsDiv = $this->getSession()
->getPage()
->find('css', '#products');
Assertion::notNull($productsDiv);
}

24. Add
Behavior
Test
Run
Behavior
Test Pass*
@jessicamauerhan | #ATO2016
Double Loop: TDD & BDD Done Right!
* A test that passes the first time
before code has been written means
the test is inaccurate or poorly
written, not added to the test suite,
or the code/feature already exists.

25. @jessicamauerhan | #ATO2016
Parts of
a Behavior Test
● Feature: Gerkhin
● Test Code
● BDD Framework /
Test Runner

26. Add
Behavior
Test
Add
Unit
Test
Run
Behavior
Test Pass*
Fail
Double Loop: TDD & BDD Done Right!
* A test that passes the first time
before code has been written means
the test is inaccurate or poorly
written, not added to the test suite,
or the code/feature already exists.
@jessicamauerhan | #ATO2016

27. @jessicamauerhan | #ATO2016
Writing Unit Tests
What is a unit?
● Unit: As small as possible
● Design and Describe behavior
○ Setup scenario for behavior
○ Cause behavior to occur
○ Assert result is as expected
● Verbose and Descriptive
Names

28. Add
Behavior
Test
Add
Unit
Test
Run Unit
Test
Run
Behavior
Test Pass*
Fail
Double Loop: TDD & BDD Done Right!
* A test that passes the first time
before code has been written means
the test is inaccurate or poorly
written, not added to the test suite,
or the code/feature already exists.
@jessicamauerhan | #ATO2016

29. @jessicamauerhan | #ATO2016
Executing Unit
Tests
● Ensures test fails
when code is broken
● Ensures test is added
to suite
● Tells you exactly what
to do next
Always execute before writing
production code

30. Add
Behavior
Test
Add
Unit
Test
Run Unit
Test
Add/Edit
Some Code
Fail
Run
Behavior
Test Pass*
Fail
Double Loop: TDD & BDD Done Right!
* A test that passes the first time
before code has been written means
the test is inaccurate or poorly
written, not added to the test suite,
or the code/feature already exists.
@jessicamauerhan | #ATO2016

31. @jessicamauerhan | #ATO2016
Writing Code
Just Enough
● Add just enough code to pass
the test
● Avoid over abstracting or
adding untested logic

32. @jessicamauerhan | #ATO2016
Three Types of Unit
Tests
● Correctness
● Contract
● Collaboration

33. New Class
For User
Registration
Class:
Registration
Service
Unit Tests
Registration Service
Correctness
Third Party
Service API
(Mailer)
Integrated
Test
MailChimp API
Forgot
Password
Weekly
Newsletter
Direct
Message
Exciting
Event
Reminder!
@jessicamauerhan | #ATO2016
TDD: Integration Testing with Contract & Collaboration Tests

34. New Class
For User
Registration
Class:
Registration
Service
Third Party
Service API
(Mailer)
Collaborator:
Mailer
Mailer
Contract
(Interface /
Abstract)
Mailer
Interface
Test Double
Persistence
Layer
Persistence
Layer
(Interface /
Abstract)
Persistence
Layer
Test Double
Fully Unit Tested &
Implemented Class:
Registration
Service
Unit Tests
Registration Service
Correctness
Collaboration
Tests
Collaboration
Tests
@jessicamauerhan | #ATO2016
TDD: Integration Testing with Contract & Collaboration Tests

35. Third Party
Service API
(Mailer)
Mailer
Implementation
Class:
Mailchimp
Adapter
New Class
For User
Registration
Class:
Registration
Service
Collaborator:
Mailer
Mailer
Contract
(Interface /
Abstract)
Mailer
Interface
Test Double
Persistence
Layer
Persistence
Layer
(Interface /
Abstract)
Persistence
Layer
Test Double
Fully Unit Tested &
Implemented Class:
Registration
Service
Unit Tests
Registration Service
Correctness
Collaboration
Tests
Collaboration
Tests
Third Party Tool:
MailChimp API
(This is a Contract)
Mailchimp
API Double
Fully Unit Tested &
Implemented Class:
Mailchimp
Adapter
Correctness
Unit Tests
Contract
Tests
Collaboration
Tests
@jessicamauerhan | #ATO2016
TDD: Integration Testing with Contract & Collaboration Tests

36. Mailer
Implementation
Class:
SendBlue
Adapter
New Class
For User
Registration
Class:
Registration
Service
Third Party
Service API
(Mailer)
Collaborator:
Mailer
Mailer
Contract
(Interface /
Abstract)
Mailer
Interface
Test Double
Persistence
Layer
Persistence
Layer
(Interface /
Abstract)
Persistence
Layer
Test Double
Fully Unit Tested &
Implemented Class:
Registration
Service
Unit Tests
Registration Service
Correctness
Collaboration
Tests
Collaboration
Tests
Third Party Tool:
SendBlue
(This is a Contract)
Third Party Tool:
SendBlue
(This is a Contract)
SendBlue
API Double
Fully Unit Tested &
Implemented Class:
SendBlue
Adapter
Class:
SendBlue
Adapter
Correctness
Unit Tests
Contract
Tests
Collaboration
Tests
@jessicamauerhan | #ATO2016
TDD: Integration Testing with Contract & Collaboration Tests
Forgot
Password
Weekly
Newsletter
Direct
Message
Exciting
Event
Reminder!

37. Maintenance
Coverage
Fragility
Duration
Cost
Number of Tests
Isolated Unit Tests
Correctness, Contract & Collaboration
Integration Testing
Multiple Components Integrated
Tested for Correctness & Communication
Behavior Tests
Fully Integrated User Experience
System Tests
load balance, performance, security
GUI
Tests

38. Add
Behavior
Test
Add
Unit
Test
Run Unit
Test
Add/Edit
Some Code
Fail
Run
Behavior
Test Pass*
Fail
@jessicamauerhan | #ATO2016
Double Loop: TDD & BDD Done Right!
* A test that passes the first time
before code has been written means
the test is inaccurate or poorly
written, not added to the test suite,
or the code/feature already exists.

39. @jessicamauerhan | #ATO2016
Failing Test or
Test Suite?
Revert!
● If the test fails, revert your
work
● Commit small changes, often!

40. Add
Behavior
Test
Add
Unit
Test
Run Unit
Test
Add/Edit
Some Code
Refactor
Run All
Unit Tests
Pass* Fail
Fail
Pass
Run
Behavior
Test Pass*
Fail
Revert Changes
@jessicamauerhan | #ATO2016
Double Loop: TDD & BDD Done Right!
Feature
Done?
NoYes
* A test that passes the first time
before code has been written means
the test is inaccurate or poorly
written, not added to the test suite,
or the code/feature already exists.

41. @jessicamauerhan | #ATO2016
Refactoring
The process of
restructuring code
without changing its
behavior

42. @jessicamauerhan | #ATO2016
Refactoring
● Improving
non-functional aspects
● Removing duplication
● Renaming
● Simplifying
Unit Tests Always Passing!
● Changes that would
break a unit test
● New functionality that
is not tested
New Unit Tests Fail, Then Pass
Adding Functionality

43. Add
Behavior
Test
Add
Unit
Test
Run Unit
Test
Add/Edit
Some Code
Refactor
Run All
Unit Tests
Run All
Behavior
Tests
Pass* Fail
Fail
Pass
Run
Behavior
Test Pass*
Fail
Fail Pass
Revert Changes
Double Loop: TDD & BDD Done Right!
Feature
Done?
NoYes
* A test that passes the first time
before code has been written means
the test is inaccurate or poorly
written, not added to the test suite,
or the code/feature already exists.
@jessicamauerhan | #ATO2016

44. @jessicamauerhan | #ATO2016
Thank You!
Double Loop:
TDD & BDD Done Right!
Feedback & Questions?
Welcome & Encouraged!
@jessicamauerhan
jessicamauerhan@gmail.com
jmauerhan.wordpress.com