test(xcat-core): the Ubuntu Genesis image ships without a DHCP client

builddeb-genesis-base builds the Genesis payload in the host root. Its
REQUIRED_PACKAGES list omits isc-dhcp-client, ifenslave and util-linux-extra, so
dracut cannot find dhclient, ifenslave or hwclock. dracut_install reports each
missing command and returns, the script does not read dracut's result, and the
.deb is packaged with the holes. A Genesis image with no dhclient never obtains a
provisioning lease, so the node netboots and never reports in.

The EL path gates the payload: xCAT-genesis-base.spec runs
verify-genesis-payload. The Ubuntu path runs no gate at all.

genesis_ubuntu_build_root.t sources the Ubuntu dracut module with dracut_install
shadowed, calls install(), and reads back the commands it installs
unconditionally. It then evaluates the REQUIRED_PACKAGES assignment and asserts
the build root supplies each one. Five of its eight assertions fail on this
commit.

Signed-off-by: Daniel Hilst <392820+dhilst@users.noreply.github.com>

xCAT-test/unit/genesis_ubuntu_build_root.t

@@ -0,0 +1,94 @@
+#!/usr/bin/env perl
+# The Ubuntu Genesis build root must carry every command the Ubuntu dracut module marks
+# mandatory. dracut_install reports a missing command and returns, so a command the build
+# root does not supply leaves a hole in the image and the build still exits 0.
+#
+# The mandatory list is read by RUNNING the module: module-setup.sh is sourced with
+# dracut_install shadowed, _dracut_install_opt neutralised (its callers are optional by
+# construction), and install() is called. The package list is read by extracting the
+# REQUIRED_PACKAGES assignment from builddeb-genesis-base and evaluating it.
+use strict;
+use warnings;
+
+use File::Temp qw(tempdir);
+use FindBin;
+use lib "$FindBin::Bin/../lib";
+use Test::More;
+
+use XCAT::Test::File qw(repo_path);
+
+my $builder = repo_path('xCAT-genesis-builder/builddeb-genesis-base');
+my $module  = repo_path('xCAT-genesis-builder/dracut_105/ubuntu/module-setup.sh');
+plan skip_all => 'builddeb-genesis-base not found' unless -f $builder;
+plan skip_all => 'ubuntu module-setup.sh not found' unless -f $module;
+plan tests => 8;
+
+# Commands the Ubuntu dracut module marks mandatory that a minimal Ubuntu server root does
+# NOT already provide, and the package that supplies each one. Every entry here has to be in
+# REQUIRED_PACKAGES or the image ships without the command.
+my %PACKAGE_FOR = (
+    dhclient  => 'isc-dhcp-client',
+    ifenslave => 'ifenslave',
+    hwclock   => 'util-linux-extra',
+);
+
+my %mandatory = map { $_ => 1 } mandatory_commands($module);
+my @packages  = required_packages($builder);
+
+for my $command (sort keys %PACKAGE_FOR) {
+    ok($mandatory{$command}, "the Ubuntu dracut module installs '$command' unconditionally");
+    ok(scalar(grep { $_ eq $PACKAGE_FOR{$command} } @packages),
+       "the build root installs $PACKAGE_FOR{$command}, which provides '$command'");
+}
+
+# doxcat asks dhclient for the provisioning lease. An image without it never gets an address,
+# so the node netboots and never reports in -- the failure this test exists for.
+ok($mandatory{dhclient} && scalar(grep { $_ eq 'isc-dhcp-client' } @packages),
+   'the Genesis image can obtain a DHCP lease');
+
+# dracut_install is silent about a hole, so the payload needs its own gate before it is
+# packaged. This is the EL path's behaviour (xCAT-genesis-base.spec runs the same verifier).
+my $text = do { open my $fh, '<', $builder or die "$builder: $!"; local $/; <$fh> };
+like($text, qr{verify-genesis-payload}, 'builddeb-genesis-base verifies the payload it packages');
+
+# mandatory_commands($module): source the dracut module with dracut_install shadowed, call
+# install(), and return the bare command names it installs unconditionally. Absolute paths are
+# data files, not commands, and are left out.
+sub mandatory_commands {
+    my ($path) = @_;
+    my $dir = tempdir(CLEANUP => 1);
+    my $driver = "$dir/collect.sh";
+    open my $fh, '>', $driver or die "$driver: $!";
+    print $fh <<"BASH";
+dracut_install() { printf '%s\\n' "\$\@"; }
+instmods() { :; }
+inst_multiple() { :; }
+inst() { :; }
+dpkg-architecture() { echo x86_64-linux-gnu; }
+. '$path'
+# Every caller of _dracut_install_opt is optional by construction: it installs only what the
+# build root already has. Neutralise it AFTER sourcing so it cannot add to the mandatory set.
+_dracut_install_opt() { :; }
+install
+BASH
+    close $fh;
+    my @out = qx{bash '$driver' 2>/dev/null};
+    BAIL_OUT("running install() from $path produced nothing") unless @out;
+    my %seen;
+    my @names = grep { !$seen{$_}++ } grep { length && !m{^/} } map { chomp; $_ } @out;
+    BAIL_OUT("install() from $path named no bare commands") unless @names;
+    return @names;
+}
+
+# required_packages($path): extract the REQUIRED_PACKAGES assignment from the build script and
+# evaluate it, so the list comes from the value the script actually uses.
+sub required_packages {
+    my ($path) = @_;
+    my $text = do { open my $fh, '<', $path or die "$path: $!"; local $/; <$fh> };
+    my ($block) = $text =~ /^(REQUIRED_PACKAGES="[^"]*")/ms;
+    BAIL_OUT("no REQUIRED_PACKAGES assignment in $path") unless $block;
+    my $out = qx{bash -c 'set -u; $block; printf "%s\\n" \$REQUIRED_PACKAGES' 2>/dev/null};
+    my @packages = grep { length } split /\s+/, ($out // '');
+    BAIL_OUT("REQUIRED_PACKAGES in $path evaluated to nothing") unless @packages;
+    return @packages;
+}