PRO TEST_CASE

command = ''
read, command, prompt='Enter an IDL display command: '

cmdlist = ['plot', 'surface', 'tv']
index = where(strlowcase(command) eq cmdlist)

case index[0] of
  0 : plot, sin(findgen(100) * 0.25)
  1 : surface, dist(32)
  2 : begin
        erase
        image = dist(400)
        tvscl, image
      end
  else : print, 'Valid display commands are: ', cmdlist
endcase

END