#NEWLINE# def test_usage_error_message( self ) : #NEWLINE# #INDENT# '\n        ``DockerBuildScript.main`` prints a usage error to ``stderr`` if there\n        are missing command line options.\n        ' #NEWLINE# fake_sys_module = FakeSysModule ( argv = [ ] ) #NEWLINE# script = DockerBuildScript ( sys_module = fake_sys_module ) #NEWLINE# try : #NEWLINE# #INDENT# script . main ( ) #NEWLINE# #UNINDENT# except SystemExit : #NEWLINE# #INDENT# pass #NEWLINE# #UNINDENT# self . assertEqual ( 'Wrong number of arguments.' , fake_sys_module . stderr . getvalue ( ) . splitlines ( ) [ ( - 1 ) ] )