Added DefaultUser test

Author: ezimuel

test/DefaultUserTest.php

@@ -0,0 +1,37 @@
+<?php
+/**
+ * @see       https://github.com/zendframework/zend-expressive-authentication for the canonical source repository
+ * @copyright Copyright (c) 2018 Zend Technologies USA Inc. (https://www.zend.com)
+ * @license   https://github.com/zendframework/zend-expressive-authentication/blob/master/LICENSE.md New BSD License
+ */
+
+declare(strict_types=1);
+
+namespace ZendTest\Expressive\Authentication;
+
+use PHPUnit\Framework\TestCase;
+use Zend\Expressive\Authentication\DefaultUser;
+use Zend\Expressive\Authentication\UserInterface;
+
+class DefaultUserTest extends TestCase
+{
+    public function testConstructor()
+    {
+        $user = new DefaultUser();
+        $this->assertInstanceOf(UserInterface::class, $user);
+    }
+
+    public function testSetGetIdentity()
+    {
+        $user = new DefaultUser();
+        $user->setIdentity('foo');
+        $this->assertEquals('foo', $user->getIdentity());
+    }
+
+    public function testSetGetRoles()
+    {
+        $user = new DefaultUser();
+        $user->setRoles(['foo', 'bar']);
+        $this->assertEquals(['foo', 'bar'], $user->getRoles());
+    }
+}