check-software: update to accept module arguments

[sadielbartholomew]

As requested in #2734 (comment), return a zero or non-zero output for a software dependency pass or fail, respectively. cylc check-software will under this implementation accept as an argument any module listed in the specification (the keys under opt_spec, including the lower-case form). Without arguments it behaves as before.

[sadielbartholomew]

I still need to check if the documentation & CLI help option (etc.) need updating for this. I will address that shortly. --help output from docstring & User Guide updated accordingly.

[TomekTrzeciak]

Thanks for not forgetting about this 👍

[TomekTrzeciak]

Could we check for multiple dependencies with a for loop here? Also, I think it would be nicer to signal success/failure through exit code rather than STDOUT. How about the following?

    exit_code = 0
    for cmd_arg in sys.argv[1:]:
        mod_arg = upper_case_conv.get(cmd_arg.lower(), cmd_arg.lower())
        if mod_arg not in module_args:
            sys.stderr.write('No such module in the software dependencies: ' +
                             cmd_arg + '\n')
            exit_code = max(exit_code, 2)
        else:
            exit_code = max(exit_code, individual_status_print(mod_arg))
    if len(sys.argv) > 1:
        sys.exit(exit_code)

[sadielbartholomew]

Yes, sorry, an exit code would be more appropriate. Okay, we can accept multiple dependency arguments too.

[sadielbartholomew]

I've just realised a docstring and the --help are not quite right as non-zero exit code is an integer giving the number of failed modules. Will rectify soon (currently preparing for imminent training, so not quite now). Everything up-to-date now.

[hjoliver]

One minor typo: in the first line of command help [ARGS] should be [MODULES] (and no need for ... as plural already).

[sadielbartholomew]

Well spotted @hjoliver! I've rectified that in a new commit & squashed it into the original.