add registery pattern and test

Author: basherr

app/Factory/Structural/RegisteryPattern/Exam/Application.php

@@ -0,0 +1,14 @@
+<?php namespace App\Factory\Structural\RegisteryPattern\Exam;
+
+class Application
+{
+  public function run()
+  {
+    $registery = ExamRegistery::getInstance();
+    $registery->set(ExamRegistery::MID_TERM_EXAM, ['math', 'physics', 'optional subject']);
+    $registery->set(ExamRegistery::FINAL_EXAM, ['math', 'physics']);
+
+    $subjects = $registery->get(ExamRegistery::FINAL_EXAM);
+    echo "<pre>Final exam subject: ";print_r($subjects);
+  }
+}

app/Factory/Structural/RegisteryPattern/Exam/ExamRegistery.php

@@ -0,0 +1,34 @@
+<?php namespace App\Factory\Structural\RegisteryPattern\Exam;
+
+class ExamRegistery
+{
+  const MID_TERM_EXAM = 'mid_term';
+  const FINAL_EXAM = 'final_exam';
+  private static $_services = [];
+  private static $_allowedExams = [self::MID_TERM_EXAM, self::FINAL_EXAM];
+  private static $_instance = null;
+
+  public static function getInstance()
+  {
+    if(self::$_instance === null) {
+      return new static;
+    }
+    return self::$_instance;
+  }
+
+  public static function setExam($key, $value)
+  {
+    if(!\in_array($key, self::$_allowedExams)) {
+      throw new \InvalidArgumentException();
+    }
+    self::$_services[$key] = $value;
+  }
+
+  public static function getExam($key)
+  {
+    if(!\array_key_exists($key, self::$_services)) {
+      throw new \InvalidArgumentException();
+    }
+    return self::$_services[$key];
+  }
+}

tests/RegisteryPatternTest.php

@@ -0,0 +1,33 @@
+<?php
+
+use App\Factory\Structural\RegisteryPattern\Exam\ExamRegistery;
+use PHPUnit\Framework\TestCase;
+
+class RegisteryPatternTest extends TestCase {
+  private static $registery;
+
+  public function setUp(): void
+  {
+    self::$registery = ExamRegistery::getInstance();
+  }
+
+  public function testCanAddAllowedKeys()
+  {
+    $final_exam_subjects = ['math', 'abc'];
+    self::$registery->setExam(ExamRegistery::FINAL_EXAM, $final_exam_subjects);
+
+    $this->assertSame($final_exam_subjects, self::$registery->getExam(ExamRegistery::FINAL_EXAM));
+  }
+
+  public function testCanThrowExceptionForInvalidKeys()
+  {
+    $this->expectException(\InvalidArgumentException::class);
+
+    self::$registery->setExam('test', '');
+  }
+
+  public function tearDown(): void
+  {
+    self::$registery = null;
+  }
+}