this is an example of a php unit test for the login of your application

LoginModuleTest.php

<?php

namespace Tests\Feature;

use Illuminate\Foundation\Testing\RefreshDatabase;
use Illuminate\Foundation\Testing\WithFaker;
use Tests\TestCase;
use App\User;
use Illuminate\Support\Facades\DB;


class LoginModuleTest extends TestCase
{
    use RefreshDatabase;

    //el usuario puede ver el formulario login
    public function test_user_can_view_a_login_form()
    {
        $response = $this->get('/login');

        $response->assertSuccessful();
        $response->assertViewIs('auth.login');
    }

    //el usuario no puede ver el formulario de login cuando esta autenticado
    public function test_user_cannot_view_a_login_form_when_authenticated()
    {
        $user = factory(User::class)->make();

        $response = $this->actingAs($user)->get('/login');

        $response->assertRedirect('/home');
    }

    // el usuario puede logearse con las credenciales correctas
    public function test_user_can_login_with_correct_credentials()
    {
        // Creamos un factory de user para que lo utilice en la prueba
        $user = factory(User::class)->create([
            'password' => bcrypt($password = '123456'),
        ]);


        $response = $this->post('/login', [
            'email' => $user->email,
            'password' => $password,
        ]);

        $response->assertRedirect('/home');
        $this->assertAuthenticatedAs($user);
    }

    // El usuario no puede logearse con credenciales incorectas
    public function test_user_cannot_login_with_incorrect_password()
    {
        $user = factory(User::class)->create([
            'password' => bcrypt('123456'),
        ]);

        $response = $this->from('/login')->post('/login', [
            'email' => $user->email,
            'password' => 'invalid-password',
        ]);

        $response->assertRedirect('/login');
        $response->assertSessionHasErrors('email');
        $this->assertTrue(session()->hasOldInput('email'));
        $this->assertFalse(session()->hasOldInput('password'));
        $this->assertGuest();
    }


    public function test_remember_me_functionality()
    {
        $user = factory(User::class)->create([
            'id' => random_int(1, 100),
            'password' => bcrypt($password = '123456'),
        ]);

        $response = $this->post('/login', [
            'email' => $user->email,
            'password' => $password,
            'remember' => 'on',
        ]);

        $response->assertRedirect('/home');
        // cookie assertion goes here
        $this->assertAuthenticatedAs($user);
    }
}