How to use client id and client secret generated by Laravel Passport in a testing?

I'm working under TDD, and I'm making a test to get a token using Password Grant Tokens with Laravel Passport, I've made the test manually (sending a curl with the client id, client secret, user and password) to the endpoint, and it works! It returns me a token, I'm using a client id and a client secret generated by the php artisan passport:install --uuids command (I've already made all previous configurations)

But now I want to write the test to generate that token, I have this code:

public function test_request_token() {

        $email = "user@test.com";
        $password = "123456";

        // Create the user
        $this->post("api/register", [
            "email" => $email,
            "password" => $password,
            "password_confirmation" => $password
        ]);

        // Ask for a token
        $response = $this->post("oauth/token", [
            'grant_type' => 'password',
            'client_id' => '92d16637-6c65-42c4-9ba2-b940d8dc3d0b',
            'client_secret' => 'Sx20PJJkmED46X2HzvhoLPHeXnoE7sNp6hNqTdBw',
            'username' => $email,
            'password' => $password,
            'scope' => ''
        ]);

        dd($response);

        $response->assertStatus(200);

    }

But it doesn't work, those credentials (client id and client secret) are the credentials that the php artisan passport:install --uuids command gave me (and are the same credentials that I've used to make the manual test with a curl that works)

I've putted a dd() function there to see what was happening, and the error is Client authentication failed so I think the test aren't reading the credentials generated by Laravel, how can I do to use those credentials?

I've tried to get credentials from the POST /oauth/clients endpoint but it says that it needs a user logged in, but I don't want to create users, my application doesn't allow clients creation, I just need one client on my application, and that client is the generated by Laravel Passport, so how can I do this?