Add CityValidatorByName.

app/Models/Validation/Validators/CityValidatorByName.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace App\Models\Validation\Validators;
+
+use App\Models\Validation\Validators\NextValidatorByName;
+use App\Models\City;
+
+class CityValidatorByName extends NextValidatorByName
+{
+    public function isCurrentValid(): bool
+    {
+        $count = City::where('name', $this->getName())->count();
+
+        return $count != 0;
+    }
+}

tests/Feature/Validation/Validators/CityValidatorByNameTest.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace Tests\Feature;
+
+use Tests\TestCase;
+
+use App\Models\Validation\Validators\CityValidatorByName;
+use App\Models\Validation\Validators\OkValidator;
+
+class CityValidatorByNameTest extends TestCase
+{
+    public function dataProvider() {
+        return [
+            'Invalid Case' => [
+                'name' => '',
+                'isValid' =>  false,
+            ],
+            'Not Found Case' => [
+                'name' => '404 City',
+                'isValid' =>  false,
+            ],
+            'Found Case' => [
+                'name' => 'testCity',
+                'isValid' =>  true,
+            ]
+        ];
+    }
+
+    public function setUpValidator(string $name): CityValidatorByName
+    {
+        return new CityValidatorByName($name, new OkValidator());
+    }
+
+    /**
+     * @dataProvider dataProvider
+     */
+    public function testGetMessage(string $name, bool $isValid): void
+    {
+        $validator = $this->setUpValidator($name);
+
+        $this->assertEquals($validator->isValid(), $isValid);
+    }
+}