Test-Laravel-Validation/tests/Feature/ValidationTest.php

<?php

namespace Tests\Feature;

use Illuminate\Foundation\Testing\RefreshDatabase;
use Tests\TestCase;

class ValidationTest extends TestCase
{
    use RefreshDatabase;

    public function test_simple_validation_rules()
    {
        // Post without any title should fail because title is required
        $response = $this->post('posts');
        $response->assertSessionHasErrors('title')->assertStatus(302);

        // Post with title should succeed
        $response = $this->post('posts', ['title' => 'Some title']);
        $response->assertStatus(200);

        // Post with the same title should fail because it's not unique
        $response = $this->post('posts', ['title' => 'Some title']);
        $response->assertSessionHasErrors('title')->assertStatus(302);
    }
}