The document discusses how to write good tests. It recommends writing tests to avoid bugs, loose time, and keep code consistent. Key points covered include testing isolated units, using different types of tests like black box and white box, and tools for testing like assertions, data providers, mock objects, and test generators. The document emphasizes writing tests early and using all available assertion methods.

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How to write good tests?
by Alexis von Glasow

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Table of contents
● Why write tests?
● What should we test?
● With what and how?

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Why write tests

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● Why write tests?
● What should we test?
● With what and how?

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LOOSE TIME

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NO BUGS
TESTS

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What should we test

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ISOLATED!!!

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Black box
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.
On ne se préoccupe que des entrée sorties.

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White box

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Unit Tests keep code
consistency!

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With what and how

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Php Tools

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Assert
public function testFailure()
{
$this->assertEquals($expected, $value, ‘message’);
$this->assertFalse(FALSE);
$this->assertTrue(TRUE);
$this->assertNull(NULL);
//…
}

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Data Provider
/**
* @dataProvider additionProvider
*/
public function testAdd($a, $b, $expected)
{
$this->assertEquals($expected, $a + $b);
}
public function additionProvider()
{
return array(
array(0, 0, 0), //success
array(0, 1, 1), //success
array(1, 0, 1), //success
array(1, 1, 3) //fail
);
}

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Generators
● https://github.com/fzaninotto/Faker
● https://github.com/nelmio/alice
● http://hoa-project.net/En/Literature/Hack/Compiler.html
● …

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Faker
// use the factory to create a FakerGenerator instance
$faker = FakerFactory::create();
// generate data by accessing properties
echo $faker->name;
// 'Lucy Cechtelar';
echo $faker->address;
// "426 Jordy Lodge
// Cartwrightshire, SC 88120-6700"
echo $faker->text;
// Sint velit eveniet. Rerum atque repellat voluptatem quia rerum. Numquam excepturi
// beatae sint laudantium consequatur. Magni occaecati itaque sint et sit tempore. Nesciunt
// amet quidem. Iusto deleniti cum autem ad quia aperiam.
// A consectetur quos aliquam. In iste aliquid et aut similique suscipit. Consequatur qui
// quaerat iste minus hic expedita. Consequuntur error magni et laboriosam. Aut aspernatur
// voluptatem sit aliquam. Dolores voluptatum est.
// Aut molestias et maxime. Fugit autem facilis quos vero. Eius quibusdam possimus est.
// Ea quaerat et quisquam. Deleniti sunt quam. Adipisci consequatur id in occaecati.
// Et sint et. Ut ducimus quod nemo ab voluptatum.

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Alice
NelmioEntityUser:
user0:
username: bob
fullname: Bob
birthDate: 1980-10-10
email: bob@example.org
favoriteNumber: 42
user1:
username: alice
fullname: Alice
birthDate: 1978-07-12
email: alice@example.org
favoriteNumber: 27
NelmioEntityGroup:
group1:
name: Admins

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Grammar PP
%skip space s
// Scalars.
%token true true
%token false false
%token null null
// Strings.
%token quote_ " -> string
%token string:string [^"]+
%token string:_quote " -> default
// Objects.
%token brace_ {
%token _brace }
// Arrays.
%token bracket_ [
%token _bracket ]
// Rest.
%token colon :
%token comma ,
%token number d+

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Grammar PP
value:
<true> | <false> | <null> | string() | object() | array() | number()
string:
::quote_:: <string> ::_quote::
number:
<number>
#object:
::brace_:: pair() ( ::comma:: pair() )* ::_brace::
#pair:
string() ::colon:: value()
#array:
::bracket_:: value() ( ::comma:: value() )* ::_bracket::

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CLASS A
CLASS C
CLASS B
Mock Me If you can

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CLASS A
CLASS C
MOCK B
CLASS A
MOCK C
CLASS B
Mock Me If you can

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Mock Me If you can
class A {
public function doSomething(B $b, C $c)
{
try {
$d = $b->doOther($c);
$d->doSomething();
} catch (Exception $e) {
return false;
}
return $d;
}
}
class B {
public function doOther(C $c)
{
if ($c->isTrue()) {
throw new Exception(‘Oups!’);
}
return new D;
}
}

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Mock Me If you can
public function test()
{
$a = new A();
$b = new B();
$mockC = $this->getMock(‘C’, array(‘isTrue’));
$mockC->expects($this->any())->method(‘isTrue’)->will($this->returnValue(false));
$a->doSomething($b, $mockC);
}
public function testRaiseException()
{
$a = new A();
$b = new B();
$mockC = $this->getMock(‘C’, array(‘isTrue’));
$mockC->expects($this->any())->method(‘isTrue’)->will($this->returnValue(true));
$a->doSomething($b, $mockC);
}

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Whenever you are tempted to
type something into a print
statement or a debugger
expression, write it as a test
instead.
-- Martin Fowler

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Bug! What to do?

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Test Driven Development
TDD

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Summary
● A good test is an existing test
● Test with provider, mock, generators!
● Use all asserters available
● Test sooner is better, easier!

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To go further

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Questions ?
For online questions, please leave a comment on the article.

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Join the community !
(in Paris)
Social networks :
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Sources
● https://github.com/atoum/atoum
● https://phpunit.de/
● http://www.simpletest.org/
● http://martinfowler.com/
● http://thenounproject.com/
Credits photos:
● useiconic.com from the Noun Project
● iconsmind.com from the Noun Project
● Luis Prado from the Noun Project
● Darren Barone from the Noun Project
● SuperAtic LABS from the Noun Project
● Julia Stoffer from the Noun Project
● CommitStrip.com
● Alexander Pretschner