Tdd is Dead, Long Live TDD

Works for
 Trainer
 Software Engineer
 @__jacker__

[test] noun
A procedure intended to establish the
quality, performance, or reliability of
something, especially before it is taken
into widespread use.

[test] verb
To do something in order to discover if
something is safe, works correctly, etc.,
or if something is present

[test] verb synonyms
Prove, Assess, Examine

class Calculator
{
public function sum($a, $b)
{
return $a + $b;
}
}

$result = $calculator->sum(2, 3);
$this->assertEquals($result, 5)

Kent Beck
“Rediscovered” TDD in 1994
“TDD By Example” –
Published 2002

Digital Computer
Programming
- Daniel Delbert McCracken 1957

The hand calculations can be done at any
point during programming. […] In these
cases it is highly desirable that the
"customer" prepare the check case,
largely because logical errors and
misunderstandings between the
programmer and customer may be
pointed out by such procedure.

PASS
REFACTOR
FAIL
RED / GREEN / REFACTOR

Kent Beck - 2002
Test-Driven Development is a
way of managing fear during
programming

What is software driven by?
Fun
Profit
Business Requirements

What is software driven by?
Requirements Examples

Test Driven Development
By
Examples

Specification by Example
– Martin Fowler 2004

Tests based on shared examples fit best in the
category of tests designed to support a team while
delivering software from a business perspective -
ensuring that the right product is built

[specification] noun
a detailed description or assessment
of requirements, dimensions,
materials, etc., as of a proposed
building, machine, bridge, etc.

[specification] in Technology
(spec) A document describing how
some system should work.

Did you write it
before the
code?
It’s a Test
It’s a
Specification
YesNo

Changing the way of thinking about the same
problem by changing the language used to
describe it

To reframe, then, means to change the
conceptual and emotional setting or viewpoint
in relation to which a situation is experienced
and to place it in another frame which fits the
'facts' of the same concrete situation equally
well or even better, and thereby changing its
entire meaning.
1974, Watzlawick, Weakland and Fisch

RSpec – 2005 –
Making TDD Productive and
Started as an experiment by Steven Baker
Fun

Don’t rush ahead with
more code.
Instead, add another
example and let it guide you
to what you have to do next.

… using tests to drive the
features and the object-
oriented structure of the
code, and using Mock
Objects to discover and
then describe
relationships between
objects

2007 - PHPSpec 1.0 - Padraic Brady & Travis Swicegood
A Port of RSpec 4
SpecBDD
2010 - PHPSpec 2.0 – Complete rewrite by –
Marcello Duarte & Konstantin Kudryashov

• public function testListContainsKeyword()
{
$basket = new Basket();
$basket->add('apple');
$this->assertTrue($basket->has('apple'));
}
What we’re going to test
Make an assertion about what it should return

• public function it_returns_true_if_it_has_an_apple()
{
$this->add('apple');
$this->has('apple’)->shouldReturn(true);
}
Specifying desired behavior
Set up an expectation of the behavior

 Returns 0 for an empty string
 Returns the “bare” number given one number
 Returns the sum of numbers separated by space
StringCalculator

Acceptance Criteria??
I want something that will
- allow searching Wikipedia for a
keyword,
- keep track of past searches
- highlights results that contain previous
search terms.
- (but not my current one)

Hmm… guess I’ll need to
- Store searched in database?
session?
- Make remote calls to wikipedia
- What’s wikipedia’s API like?
- What color will the highlight be?

Focus on one Problem
- Ignore the infrastructure
- Ignore the framework
- What’s left?

Your Domain /
Business Logic
Remote
API

Your Domain /
Business Logic
Wikipedia
Search
Client
+ searchFor(term)
SearchHistory
+ track(term)
+ findAll() : array
SearchController
+ lookup(term)
HighlightingSearch
+ search(term)
SearchResult
+ highlight()
+ matches(history)
0..*

Collaborators
Client
+ searchFor(term)
SearchHistory
+ track(term)
+ findAll() : array
HighlightingSearch
+ search(term)
SearchResult
+ highlight()
+ matches(history)

Doubles / Mocks
Client
+ searchFor(term)
SearchHistory
+ track(term)
+ findAll() : array
HighlightingSearch
+ search(term)
SearchResult
+ highlight()
+ matches(history)
0..*

class HighlightingSearchSpec extends ObjectBehavior
{
function let(SearchHistory $searchHistory, Client $client)
{
$this->beConstructedWith($searchHistory, $client);
}
}

class HighlightingSearchSpec extends ObjectBehavior
{
function let(SearchHistory $searchHistory, Client $client)
{
$this->beConstructedWith($searchHistory, $client);
}
}
double double

class HighlightingSearch
{
private $searchHistory;
private $client;
public function __construct(
SearchHistory $searchHistory,
Client $client
) {
$this->searchHistory = $searchHistory;
$this->client = $client;
}
}

class HighlightingSearch
{
private $searchHistory;
private $client;
public function __construct(
SearchHistory $searchHistory,
Client $client
) {
$this->searchHistory = $searchHistory;
$this->client = $client;
}
}
dependency dependency

namespace AcmeWiki;
interface SearchHistory
{
public function add(string $term);
public function findAll() : array;
}

namespace AcmeWiki;
interface Client
{
public function searchFor(string $term) : array;
}

namespace AcmeWiki;
interface SearchResult
{
public function highlight();
public function matches(array $historicTerms) : bool;
}

 Keeps track of search history
 Returns a collection of search results
 Highlights results whose titles do match historic terms
 Does not highlight any results if there is no search history
 Does not highlight results whose titles don’t match historic terms
 Ignores the current search term
 Only matches whole words
HighlightingSearch

 Does not highlight results whose titles don’t match historic terms
HighlightingSearch
delegated to SearchResult

 Does not highlight results whose title don’t match historic terms
HighlightingSearch

 Does not highlight results whose title don’t match historic terms
HighlightingSearch
Is this a requirement?

Tdd is Dead, Long Live TDD

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