test(nodestat): pin the fping option and the usemon abbreviations

Add a unit test for the option that selects fping instead of nmap.

The test takes the specification out of the plugin source and gives it to
Getopt::Long with the settings that the daemon uses, so it drives the
specification that the plugin ships.

It shows that -f, --usefping and the older --useping each select fping, that
--use and --us still select usemon and do not select fping, that the bundles
-mf and -fm select both options, and that both places parse through the one
specification.

xCAT-test/unit/nodestat_usefping_option.t

@@ -0,0 +1,79 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+
+use FindBin;
+use File::Spec;
+use Test::More;
+use Getopt::Long qw(GetOptionsFromArray);
+
+my $plugin = File::Spec->catfile( $FindBin::Bin, '..', '..',
+    'xCAT-server', 'lib', 'xcat', 'plugins', 'nodestat.pm' );
+plan skip_all => 'nodestat.pm not found' unless -r $plugin;
+
+open( my $fh, '<', $plugin ) or die "Unable to read $plugin: $!";
+my $source = do { local $/; <$fh> };
+close($fh);
+
+# nodestat parses its arguments twice, once in the preprocessor and once in the
+# handler. Both have to read the same specification, or an option that one
+# accepts is dropped or misread by the other.
+my $calls = () = $source =~ /GetOptions\s*\(\s*\\%opt,\s*option_spec\(\)\s*\)/g;
+is( $calls, 2, 'both places parse through the one specification' );
+
+my ($routine) = $source =~ /(sub option_spec \{.*?\n\}\n)/s;
+BAIL_OUT('could not extract option_spec from nodestat.pm') unless $routine;
+eval "package NodestatSpec; $routine 1;" or BAIL_OUT("could not evaluate: $@");
+
+# The daemon leaves Getopt::Long in pass_through, because xCAT::Usage sets it
+# and the setting lasts for the life of the process.
+sub parse {
+    my (@argv) = @_;
+    Getopt::Long::ConfigDefaults();
+    Getopt::Long::Configure( 'pass_through', 'bundling' );
+    $Getopt::Long::ignorecase = 0;
+    my %opt;
+    do { local $SIG{__WARN__} = sub { }; GetOptionsFromArray( \@argv, \%opt, NodestatSpec::option_spec() ) };
+    return \%opt;
+}
+
+# The option that the manual page and the usage message give.
+foreach my $given (qw(-f --usefping)) {
+    ok( parse($given)->{f}, "$given selects fping" );
+}
+
+# The spelling that the code has carried since 2.14.2. A site can have it in a
+# script, so it keeps working.
+ok( parse('--useping')->{f}, '--useping still selects fping' );
+
+# usemon owns these abbreviations. They were unambiguous before the fping
+# option gained a long name beginning with the same letters, and an
+# administrator who monitors with them must not silently lose monitoring.
+foreach my $given (qw(--use --us --usemon -m)) {
+    my $opt = parse($given);
+    ok( $opt->{m}, "$given still selects usemon" );
+    ok( !$opt->{f}, "$given does not select fping" );
+}
+
+# Short options bundle, so both orders have to give both settings.
+foreach my $given (qw(-mf -fm)) {
+    my $opt = parse($given);
+    ok( $opt->{m} && $opt->{f}, "$given selects usemon and fping" );
+}
+
+# The other options keep their own letters.
+is_deeply(
+    [ map { parse($_) } qw(-u -p -q) ],
+    [ { u => 1 }, { p => 1 }, { q => 1 } ],
+    'the remaining options are unchanged'
+);
+
+# The usage text is what an administrator types.
+my ($usage) = $source =~ /(nodestat \[noderange\][^"]*)/;
+ok( defined $usage, 'the usage message was found' );
+my ($long) = grep { /^f\|/ } NodestatSpec::option_spec();
+($long) = $long =~ /^f\|([^|]+)/;
+ok( defined $usage && $usage =~ /--\Q$long\E/,
+    'the usage message names the option that the code accepts' );
+
+done_testing();