PHPunit example

tests/EmailTest.php

@@ -0,0 +1,27 @@
+<?php declare(strict_types=1);
+use PHPUnit\Framework\TestCase;
+use MMK2410\MyTodoList\Email;
+
+final class EmailTest extends TestCase
+{
+    private $email = 'user@example.com';
+
+    public function testCanBeCreatedFromValidEmailAddress(): void {
+        $this->assertInstanceOf(
+            Email::class,
+            Email::fromString($this->email)
+        );
+    }
+
+    public function testCannotBeCreatedFromInvalidEmailAddress(): void {
+        $this->expectException(InvalidArgumentException::class);
+        Email::fromString('invalid');
+    }
+
+    public function testCanBeUsedAsString(): void {
+        $this->assertEquals(
+            $this->email,
+            Email::fromString($this->email)
+        );
+    }
+}