Test driven development and The value object pattern

Test driven development

With the value object pattern , First we should write a test file , and if use Zend Studio Editer we can generate test file from file | new | PHPUnit Test Case . Then the test file about four operations just like this:

 

<?php//file CalculatorTest.phprequire_once 'calculator.php';require_once 'PHPUnit/Framework/TestCase.php';/** * Calculator test case. */class CalculatorTest extends PHPUnit_Framework_TestCase {/** * @var Calculator */private $Calculator;/** * Prepares the environment before running a test. */protected function setUp() {parent::setUp ();// TODO Auto-generated CalculatorTest::setUp()$this->Calculator = new Calculator();}/** * Cleans up the environment after running a test. */protected function tearDown() {// TODO Auto-generated CalculatorTest::tearDown()$this->Calculator = null;parent::tearDown ();}/** * Constructs the test case. */public function __construct() {// TODO Auto-generated constructor}/** * Tests Calculator->add() */public function testAdd() {// TODO Auto-generated CalculatorTest->testAdd()//$this->markTestIncomplete ( "add test not implemented" );$a = 11;$b = 12;$this->assertEquals(23, $this->Calculator->add($a,$b));}/** * Tests Calculator->multiply() */public function testMultiply() {$a = 11;$b = 12;$this->assertEquals(132, $this->Calculator->multiply($a,$b));}/** * Tests Calculator->divide() */public function testDivide() {$a = 24;$b = 12;$this->assertEquals(2, $this->Calculator->divide($a,$b));}/** * Tests Calculator->subtract() */public function testSubtract() {$a = 24;$b = 12;$this->assertEquals(12, $this->Calculator->subtract($a,$b));}}//end of file CalculatorTest.php

 

 

 

Then based the test code above this is a class about four operations :

 

<?php// file calculator.phpclass Calculator {public function add($a, $b) {return $a + $b;}public function multiply($a, $b) {return $a * $b;}public function divide($a, $b) {if ($b == null) {throw new Exception ( "Division by zero" );}return $a / $b;}public function subtract($a, $b) {return $a - $b;}}//end of calculator.php file

 

Finally , run the test file with click right | run as | PHPUnit Test to check whether there have some bug or not.

 

The value object pattern

Generally , There are three features in the value object pattern:

• The property should be protected (will be defined with protected of private) , cann't be public;
• The property should be assigned in the construct;
• The property shouldn't be changed in any methods , if you want to chang it , you must build a new object which the property been set to new value.

 

Frist we still should make a test file :

 

<?php//file valueObjectTest.phprequire_once 'valueObjectClass.php';require_once 'PHPUnit/Framework/TestCase.php';class valueObjectClass extends PHPUnit_Framework_TestCase{/** * Prepares the environment before running a test. * */protected function setUp() {parent::setUp ();}/** * Cleans up the environment after running a test. */protected function tearDown() {parent::tearDown ();}public function __construct(){}/** * test class work dollar person */function testDollarWorking() {$job = new Work;$p1 = new Person;$p2 = new Person;//Every new dollar class's amount was 200$this->assertEquals(200, $job->payDay()->getAmount());//this will deliver a dollar class to $p1->wallet and the amount is 200$p1->wallet = $job->payDay();$this->assertEquals(200, $p1->wallet->getAmount());//same to up$p2->wallet = $job->payDay();$this->assertEquals(200, $p2->wallet->getAmount());//thiw will return a new dollar class to $p1->wallet and the amount add to 400$p1->wallet = $p1->wallet->add($job->payDay());$this->assertEquals(400, $p1->wallet->getAmount());}function testGame() {$game = new Monopoly ();$player1 = new Player ( 'Jason' );//Jason's initial amount is 1500$this->assertEquals ( 1500, $player1->getBalance () );//give the player 200 another$game->passGo ( $player1 );$this->assertEquals ( 1700, $player1->getBalance () );$game->passGo ( $player1 );$this->assertEquals ( 1900, $player1->getBalance () );}function testRent() {$game = new Monopoly;$player1 = new Player('Madeline');$player2 = new Player('Caleb');$this->assertEquals(1500, $player1->getBalance());$this->assertEquals(1500, $player2->getBalance());//rent 26 dollar to player1 from player2$game->payRent($player1, $player2, new Dollar(26));$this->assertEquals(1474, $player1->getBalance());$this->assertEquals(1526, $player2->getBalance());}}//end of valueObjectTest.php

 

Then this is the example about the value object pattern based on test file above:

 

<?php//file valueObjectClass.phpclass Monopoly {protected $go_amount;/** * game constructor * @return void */public function __construct() {//initialize to a dollar class $this->go_amount = new Dollar ( 200 );}/** * pay a player for passing * @param Player $player the player to pay * @return void */public function passGo($player) {//Give player 200 dollars$player->collect ( $this->go_amount );}/*** pay rent from one player to another* @param Player $from the player paying rent* @param Player $to the player collecting rent* @param Dollar $rent the amount of the rent* @return void*/public function payRent($playerFrom, $playerTo, $rent) {//The playerfrom will add $rent dollars and playerto will reduce $rent dollars$playerTo->collect($playerFrom->pay($rent));}}class Player {protected $name;protected $savings;/** * constructor * set name and initial balance * @param string $name the players name * @return void */public function __construct($name) {$this->name = $name;$this->savings = new Dollar ( 1500 );}/** * receive a payment * @param Dollar $amount the amount received * @return void */public function collect($amount) {$this->savings = $this->savings->add ( $amount );}/** return player balance * @return float */public function getBalance() {return $this->savings->getAmount ();}/*** make a payment* @param Dollar $amount the amount to pay* @return Dollar the amount payed*/public function pay($amount) {$this->savings = $this->savings->debit($amount);return $amount;}}/** * this class is the core of value object pattern * the $amount is build when the class is instance and cann't be changed * you can only return a new dollar class when you want the diferent value of $amount * @author hahaliu * */class Dollar {protected $amount;public function __construct($amount = 0) {//amount be defined and shoudn't chang it in other function $this->amount = ( float ) $amount;}public function getAmount() {return $this->amount;}public function add($dollar) {return new Dollar ( $this->amount + $dollar->getAmount () );}public function debit($dollar) {return new Dollar ( $this->amount - $dollar->getAmount () );}}class Work {protected $salary;public function __construct() {$this->salary = new Dollar ( 200 );}public function payDay() {return $this->salary;}}class Person {public $wallet;}//end of valueObjectClass.php