PHP7 Singleton

Creational/Singleton/Singleton.php

@@ -2,22 +2,17 @@
 
 namespace DesignPatterns\Creational\Singleton;
 
-/**
- * class Singleton.
- */
 class Singleton
 {
     /**
-     * @var Singleton reference to singleton instance
+     * @var Singleton
      */
     private static $instance;
 
     /**
-     * gets the instance via lazy initialization (created on first usage).
-     *
-     * @return self
+     * gets the instance via lazy initialization (created on first usage)
      */
-    public static function getInstance()
+    public static function getInstance(): Singleton
     {
         if (null === static::$instance) {
             static::$instance = new static();
@@ -27,33 +22,30 @@ class Singleton
     }
 
     /**
-     * is not allowed to call from outside: private!
+     * is not allowed to call from outside to prevent from creating multiple instances,
+     * to use the singleton, you have to obtain the instance from Singleton::getInstance() instead
      */
     private function __construct()
     {
     }
 
     /**
-     * prevent the instance from being cloned.
+     * prevent the instance from being cloned (which would create a second instance of it)
      *
      * @throws SingletonPatternViolationException
-     *
-     * @return void
      */
     final public function __clone()
     {
-        throw new SingletonPatternViolationException('This is a Singleton. Clone is forbidden');
+        throw new \Exception('This is a Singleton. __clone is forbidden');
     }
 
     /**
-     * prevent from being unserialized.
+     * prevent from being unserialized (which would create a second instance of it)
      *
      * @throws SingletonPatternViolationException
-     *
-     * @return void
      */
     final public function __wakeup()
     {
-        throw new SingletonPatternViolationException('This is a Singleton. __wakeup usage is forbidden');
+        throw new \Exception('This is a Singleton. __wakeup is forbidden');
     }
 }

Creational/Singleton/Tests/SingletonTest.php

@@ -4,32 +4,19 @@ namespace DesignPatterns\Creational\Singleton\Tests;
 
 use DesignPatterns\Creational\Singleton\Singleton;
 
-/**
- * SingletonTest tests the singleton pattern.
- */
 class SingletonTest extends \PHPUnit_Framework_TestCase
 {
     public function testUniqueness()
     {
         $firstCall = Singleton::getInstance();
-        $this->assertInstanceOf('DesignPatterns\Creational\Singleton\Singleton', $firstCall);
         $secondCall = Singleton::getInstance();
+
+        $this->assertInstanceOf('DesignPatterns\Creational\Singleton\Singleton', $firstCall);
         $this->assertSame($firstCall, $secondCall);
     }
 
-    public function testNoConstructor()
-    {
-        $obj = Singleton::getInstance();
-
-        $refl = new \ReflectionObject($obj);
-        $meth = $refl->getMethod('__construct');
-        $this->assertTrue($meth->isPrivate());
-    }
-
     /**
      * @expectedException \DesignPatterns\Creational\Singleton\SingletonPatternViolationException
-     *
-     * @return void
      */
     public function testNoCloneAllowed()
     {
@@ -39,13 +26,11 @@ class SingletonTest extends \PHPUnit_Framework_TestCase
 
     /**
      * @expectedException \DesignPatterns\Creational\Singleton\SingletonPatternViolationException
-     *
-     * @return void
      */
     public function testNoSerializationAllowed()
     {
         $obj1 = Singleton::getInstance();
         $serialized = serialize($obj1);
-        $obj2 = unserialize($serialized);
+        unserialize($serialized);
     }
 }