added phpunit and composer stuff

tests/unit/TestEmail.php

@@ -0,0 +1,30 @@
+<?php
+declare(strict_types=1);
+
+use PHPUnit\Framework\TestCase;
+use model\forum\Email;
+final class TestEmail extends TestCase
+{
+    public function testCanBeCreatedFromValidEmailAddress(): void
+    {
+        $this->assertInstanceOf(
+            Email::class,
+            new Email('user@example.com')
+        );
+    }
+
+    public function testCannotBeCreatedFromInvalidEmailAddress(): void
+    {
+        $email = new Email('user');
+        $this->assertFalse($email->getValid());
+        $this->assertEquals($email->getEmail(), 'invalid');
+    }
+
+    public function testCanBeUsedAsString(): void
+    {
+        $this->assertEquals(
+            'user@example.com',
+            new Email('user@example.com')
+        );
+    }
+}