How to mock the method of a model that reviews one or more instances of another model with PhpUnit?

I'm doing unit tests on the different responses of the roads (usually the roads are protected with authentication). I managed to mock the user authentication. However, I can't mock the method of my models that calls to the database because I have database connection errors.

Do you know how mock his methods without calling him to the database ?

this is what I did.

• Controller

    class XYZController extends Controller{

    ...
        public function index(Request $request){
            $user   = Auth::user();
            $person = $user->person()->first(); // how mock the method person - from the I have the database error.
            $phone  = $user->phone()->first();// how mock the method phone
            $prefix = $phone->country()->first()->code; // how mock the method country
            $email  = $user->email;
            $pays   = Pays::where('xyz', false)->get(); // how mock the method person
    ...
            return view('xyz',[
                ...
            ]);
        }
    ...
    }

• Test

    class XYZTest extends TestCase{

        public function testRouteMain(){
          $user = factory(User::class)->make();
          $person = factory(Person::class)->make();

          $this->withoutMiddleware();
          $this->be($user);

          $mockUser = Mockery::mock(User::class);

          $mockUser->shouldReceive('person')->andReturn(collect());
          $mockUser->shouldReceive('first')->andReturn($person);
          $this->app->instance(User::class, $mockUser);
          $reponse = $this->get(route('xyz_route'));

          $this->assertEquals(Response::HTTP_OK, $reponse->>getStatusCode(), 'The status code expected is '.Response::HTTP_OK);// I put the doubles ">>" on purpose , it's to avoid having the blockquote
       }
    }