OS X 10.11.3
SDL2 2.0.4
--- The following code paints a yellow rect, but I do not get a window.
--- Removing the surface code, does not create an empty window either.

#include <stdio.h>
#include <SDL2/SDL.h>

const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;

int main ( int argc, char** argv )
{
    SDL_Window * window = NULL;
    SDL_Surface * surface = NULL;

    // initialize SDL video
    if ( SDL_Init( SDL_INIT_VIDEO ) < 0 )
    {
        printf( "Unable to init SDL: %s\n", SDL_GetError() );
        return 1;
    }

    // make sure SDL cleans up before exit
    atexit(SDL_Quit);
    window = SDL_CreateWindow("Hi world!",
                              SDL_WINDOWPOS_UNDEFINED,
                              SDL_WINDOWPOS_UNDEFINED,
                              SCREEN_WIDTH,
                              SCREEN_HEIGHT,
                              SDL_WINDOW_RESIZABLE);
    if (window == NULL)
    {
        printf("Window not created: %s\n",SDL_GetError());
    }
    else
    {
        surface = SDL_GetWindowSurface(window);
        SDL_FillRect(surface,NULL,SDL_MapRGBA(surface->format,255,255,0,255));
        SDL_UpdateWindowSurface(window);
        SDL_Delay(5000);
    }

   SDL_DestroyWindow(window);
   SDL_Quit();


    // all is well ;)
    printf("Exited cleanly\n");
    return 0;
}