Testing with PEST

I am a complete novice in testing and I wanted to know if someone could guide me on what I'm doing wrong. I want to test the following function in my php laravel project:

public static function getFlatSupplierAddress($supplier_address_id): string
    {
        $supplierAddress = Address::findOrFail($supplier_address_id);
        return $supplierAddress->street . " " .
            $supplierAddress->number . " " .
            $supplierAddress->apartment . ", " .
            ($supplierAddress->city ? $supplierAddress->city->name : '') . ", " .
            ($supplierAddress->province ? $supplierAddress->province->name : '') . ", " .
            ($supplierAddress->country ? $supplierAddress->country->name : '');
    }

This is my test code:

it('returns the formatted supplier address', function () {

        $addressMock = Mockery::mock(Address::class);

        $addressMock->shouldReceive('findOrFail')
            ->with(1)
            ->andReturnSelf(); // Retorna el mismo mock

        $addressMock->shouldReceive('getAttribute')
            ->with('street')
            ->andReturn('Calle');
        $addressMock->shouldReceive('getAttribute')
            ->with('number')
            ->andReturn('456');
        $addressMock->shouldReceive('getAttribute')
            ->with('apartment')
            ->andReturn('Apt 789');
        $addressMock->shouldReceive('city')
            ->andReturn((object)['name' => 'Retiro']);
        $addressMock->shouldReceive('province')
            ->andReturn((object)['name' => 'Buenos Aires']);
        $addressMock->shouldReceive('country')
            ->andReturn((object)['name' => 'Argentina']);

        $expectedAddress = 'Calle 456 , Retiro, Buenos Aires, Argentina';

        $formattedAddress = AddressService::getFlatSupplierAddress(1);

        // Assert
        expect($formattedAddress)->toBe($expectedAddress);

Of course I have the problem that I am not using well the Mock since the function returns me a string of an address that it found in the database and it is comparing it with the Mock that I have created. I don't understand how to simulate this kind of things. And of course I used ChatGPT D:

source https://stackoverflow.com/questions/77018462/testing-with-pest