@Test
public void testMissingArgument() throws Exception {

  tool.execute(new String[]{GetDiscoveryDocAction.NAME,
      option(EndpointsToolAction.OPTION_CLASS_PATH_SHORT), "classPath",
      option(EndpointsToolAction.OPTION_OUTPUT_DIR_SHORT), "outputDir",
      option(EndpointsToolAction.OPTION_HOSTNAME_SHORT), "foo.com"});
  assertTrue(usagePrinted);
}