Autoloader unit test - first attempt

Question

I am learning TDD and I want to test my AutoLoader class, what needs to do the next job:

• do a check is the namespace is string
• do a check, is the path to directory parameter is a string
• do a check is the path to directory what I want to load is exists, directory and readable.

There will be more jobs, but I am newbee, so I need your opinion about my test:

<?php
namespace Myframework\Application\Autoloader;
class Autoloader {
 /**
 * @var string
 */
 protected $namespace;
 /**
 * @var string
 */
 protected $path;
 public function __construct($namespace, $pathToClassesDirectory = '') {
 if (!is_string($namespace)) {
 throw new \Exception('Namespace must be string');
 }
 if (!is_string($pathToClassesDirectory)) {
 throw new \Exception('Path to directory parameter should be string');
 }
 if (!file_exists($pathToClassesDirectory) || !is_dir($pathToClassesDirectory) || !is_readable($pathToClassesDirectory)) {
 throw new \Exception('Path to directory is not accessible to read: "' . $pathToClassesDirectory . '"');
 }
 $this->namespace = $namespace;
 $this->path = $pathToClassesDirectory;
 }
}

The class:

 <?php
use PHPUnit\Framework\TestCase;
/**
 * @author vaso
 */
require_once '../system/Application/Autoloader/Autoloader.php';
class AutoloaderTest extends TestCase {
 protected $Autoloader;
 public function setUp() {
 $this->Autoloader = new Myframework\Application\Autoloader\Autoloader(TEST_NAMESPACE, BASE_PATH);
 }
 public function tearDown() {
 unset($this->Autoloader);
 }
 public function testConstructorCall() {
 new Myframework\Application\Autoloader\Autoloader('nameSpaceAsString', BASE_PATH);
 }
 public function testConstructorCallNameSpaceIsNotStringException() {
 $this->expectException('Exception');
 new Myframework\Application\Autoloader\Autoloader(2);
 }
 public function testConstructorCallPathIsNotStringException() {
 $this->expectException('Exception');
 $notStringForPath = new stdClass();
 new Myframework\Application\Autoloader\Autoloader(TEST_NAMESPACE, $notStringForPath);
 }
 public function testIsDirectoryExistsException() {
 $this->expectException('Exception');
 new Myframework\Application\Autoloader\Autoloader('x', 'Failed directory what not exist');
 }
}

Test passed, and my methods are works, I am happy. But I doubt this is not how TDD works even if I follow every requirements.

My questions are:

• Is it ok to use constants in test what comes from bootstrap.php to define path?
• All of the test ok, but is this the right way to test a constructor? I feel no for some reason, if its ok, please tell me, if not, please tell me why.

I found a lot of resources about TDD, videos, books, but testing the constructor is not in it.

• Mike Brant: Not sure I am following. Where does loading actually happen? Also, I would think that in this day and age, if one were to build an autoloader, they would do son in PSR-4 compliant fashion. See PSR-4 examples implementations here: github.com/php-fig/fig-standards/blob/master/accepted/… I guess I don't understand the need to "roll your own" autoloader at this point when this is territory that is very well covered in PHP.
• vaso123: Load is not implemented yet, and I am loading as PSR suggested in other projects. That is a unit, what I can test by unit test. Yes, I am know unit test is for units, but if I want to be sure that my code is coveraged I should write tests for the constructor too.

Answer 1

After some research, I've got these answers:

Testing constructor is totally unnecessary if you follow this: Constructor does Real Work. Unit test for units. The constructor only job is to build the object, nothing else, no new objects creation, no initializing, etc...

For constants: I see no reason why do not use constants (for example for a path) to help me to access my classes for tests.