shaikhul

<?php
/**
* Use spy when we want to be sure that the authorize method was called
* Warning: the more we spy, the tighter we couple our tests to the implementation of our system which leads to fragile tests
*/
class AcceptingAuthorizerSpy extends Authorizer {
    
    $authorize_was_called = false;
       
    public function authorize() {

shaikhul

<?php

/**
* Stub example: We will use this stub whenenver we need to test a system that requires a logged in user
*/
class AcceptingAuthorizerStub implements Authorizer {
    public function authorize($username, $password) {
       // always return true
       return $true;
    }

shaikhul

<?php

require_once "DummyAuthorizer.php";
require_once "System.php";
    
function test_system_has_no_loggedin_users() {
    /*
    * In this test I want to test loginCount() method and we don't need to provide any real authorizer to create the system object
    * So we are passing a DummyAuthorizer whose authorize method would never be called from this test 
    */  

shaikhul

<?php

require_once "AuthorizerInterface.php";
    
class System {
    public function __construct(AuthorizerInterface $authorizer) {
        $this->authorizer = $authorizer;
    } 
    
    public function loginCount() {

shaikhul

<?php

require_once "AuthorizerInterface.php";
    
/**
* Example of Test doubles, informally its being called as Mock (but not a real mock)
*/
class Authorizer implements AuthorizerInterface {
    public function authorize($username, $password) {
        // it implements actual authorization logic

shaikhul

<?php

require_once "AuthorizerInterface.php";
    
/**
* Example of Test doubles, informally its being called as Mock (but not a real mock)
*/
class DummyAuthorizer implements AuthorizerInterface {
    public function authorize($username, $password) {
        return null;

shaikhul

<?php

interface AuthorizerInterface {
    public function authorize($username, $password);
}

shaikhul

<?php

// define a curry function
$make_adder = function ($num1) {
    return function ($num2) use ($num1) {
        return $num1 + $num2;
    };
};

$five_adder = $make_adder(5);

shaikhul

<?php

// define a function that accepts a callable
function decorate(callable $func) {
    return "<p>" . $func() . "</p>";
}

// execute decorate by passing an anonymous function
$result = decorate(function () {
    return "Hello World!";

shaikhul

<?php
// create a lamda function by assigning an anonymous function to a variable
$greet = function ($name) {
     return "Hello {$name}";
};

// it will print Hello World
echo $greet("World") . PHP_EOL;