Uses WP's is_email() to validate email addresses in Subscriber model

tests/unit/Models/ModelValidatorTest.php

@@ -0,0 +1,24 @@
+<?php
+
+use MailPoet\Models\ModelValidator;
+
+class ModelValidatorTest extends MailPoetTest {
+  public $validator;
+
+  function __construct() {
+    $this->validator = new ModelValidator();
+  }
+
+  function testItConfiguresValidators() {
+    $configured_validators = $this->validator->getValidators();
+    foreach(array_keys($this->validator->validators) as $validator) {
+      expect($configured_validators)->contains($validator);
+    }
+  }
+
+  function testItValidatesEmail() {
+    expect($this->validator->validateEmail('test'))->false();
+    expect($this->validator->validateEmail('tést@éxample.com'))->false();
+    expect($this->validator->validateEmail('test@example.com'))->true();
+  }
+}