Add Natural validator

src/Validator/NaturalValidator.php

@@ -0,0 +1,30 @@
+<?php declare(strict_types=1);
+/**
+ * This file is part of the daikon-cqrs/validize project.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Daikon\Validize\Validator;
+
+use Daikon\Interop\Assert;
+use Daikon\ValueObject\Natural;
+
+final class NaturalValidator extends Validator
+{
+    /** @param mixed $input */
+    protected function validate($input): Natural
+    {
+        $settings = $this->getSettings();
+        $min = $settings['min'] ?? 0;
+        $max = $settings['max'] ?? PHP_INT_MAX;
+
+        Assert::that($input)
+            ->integerish('Must be an integer.')
+            ->greaterOrEqualThan($min, "Must be at least $min.")
+            ->lessOrEqualThan($max, "Must be at most $max.");
+
+        return Natural::fromNative($input);
+    }
+}