wic: Return error code when wic fails to invoke command

Return 1 if command doesn't exist or wic is called without
any commmand.
Return result of invoke_command as wic return code.

Added tests for unsupported command and no command.

Fixed typo in test case test02_createhelp spotted by this fix.

[YOCTO #7856]

(From OE-Core rev: ebd9f7b1da8ed556e98aab4d5f4e81707ac44b27)

Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/image/help.py

@@ -81,11 +81,13 @@ def invoke_subcommand(args, parser, main_command_usage, subcommands):
     if not args:
         logging.error("No subcommand specified, exiting")
         parser.print_help()
+        return 1
     elif args[0] == "help":
         wic_help(args, main_command_usage, subcommands)
     elif args[0] not in subcommands:
         logging.error("Unsupported subcommand %s, exiting\n" % (args[0]))
         parser.print_help()
+        return 1
     else:
         usage = subcommands.get(args[0], subcommand_error)[1]
         subcommands.get(args[0], subcommand_error)[0](args[1:], usage)

scripts/wic

@@ -305,7 +305,7 @@ def main(argv):
                 parser.print_help()
                 sys.exit(1)
 
-    hlp.invoke_subcommand(args, parser, hlp.wic_help_usage, subcommands)
+    return hlp.invoke_subcommand(args, parser, hlp.wic_help_usage, subcommands)
 
 
 if __name__ == "__main__":