I am coming from a Laravel background, where I can create a “Feature test” which goes something like this:

public function test_user_can_register()
{
    // Arrange
    $userData = [
        'name' => 'John Doe',
        'email' => '[email protected]',
        'password' => 'password123',
    ];

    // Create a user using the factory
    $user = User::factory()->create($userData);

    // Act
    $response = $this->post('/register', $userData);

    // Assert
    $response->assertStatus(302);
    $response->assertRedirect('/home');
    $this->assertDatabaseHas('users', ['email' => '[email protected]']);
}

Questions related to testing in NestJS:

• There are a controller.spec and service.spec files. Why is that? why not just use the controller to write my “Feature test”. What is the point of service.spec file?
• In Laravel, there is (model-factories) and (resetting-the-database-after-each-test) concepts, is there something similar like this in NestJS?