WIP add customer test

src/Glassboxx/ValueObject/CustomerInterface.php

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Opdavies\Glassboxx\ValueObject;
+
+interface CustomerInterface
+{
+    public function __construct(
+        string $firstName,
+        string $lastName,
+        string $emailAddress
+    );
+
+    public function getEmailAddress(): string;
+
+    public function getFirstName(): string;
+
+    public function getLastName(): string;
+}