Add a validator interface, UpperRangeValidator and OkValidator.

tests/Unit/Validation/Validators/OkValidatorTest.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace Tests\Unit;
+
+use PHPUnit\Framework\TestCase;
+
+use App\Models\Validation\Validators\OkValidator;
+
+class OkValidatorTest extends TestCase
+{
+    public function testIsValid(): void
+    {
+        $validator = new OkValidator();
+
+        $this->assertTrue($validator->isValid());
+    }
+}