spec: build systemd-tests package

As it's a hard requirement for the upstream integration test suite.

Related: RHEL-79976

split-files.py

@@ -68,6 +68,7 @@ outputs = {suffix: open(f'.file-list-{suffix}', 'w')
                    'devel',
                    'container',
                    'oomd',
+                   'tests',
                    'remote',
                    'resolve',
                    'main',
@@ -101,6 +102,8 @@ for file in files(buildroot):
         o = outputs['pam']
     elif '/rpm/' in n:
         o = outputs['rpm-macros']
+    elif '/usr/lib/systemd/tests' in n:
+        o = outputs['tests']
     elif 'ukify' in n:
         o = outputs['ukify']
     elif re.search(r'/libsystemd-(shared|core)-.*\.so$', n):

systemd.spec

@@ -892,6 +892,20 @@ systemd-oomd is a system service that uses cgroups-v2 and pressure stall
 information (PSI) to monitor and take action on processes before an OOM
 occurs in kernel space.
 
+%package tests
+Summary:       Internal unit tests for systemd
+Requires:      %{name}%{_isa} = %{version}-%{release}
+# This dependency is provided transitively. Also add it explicitly to
+# appease rpminspect, https://github.com/rpminspect/rpminspect/issues/1231:
+Requires:      %{name}-libs%{_isa} = %{version}-%{release}
+Requires:      python3dist(psutil)
+
+License:       LGPL-2.1-or-later
+
+%description tests
+"Installed tests" that are usually run as part of the build system. They can be
+useful to test systemd internals.
+
 %prep
 %autosetup -S git
 
@@ -950,7 +964,7 @@ CONFIGURE_OPTS=(
         -Dfirst-boot-full-preset=true
         -Ddefault-network=true
         -Dtests=unsafe
-        -Dinstall-tests=false
+        -Dinstall-tests=true
         -Dnobody-user=nobody
         -Dnobody-group=nobody
         -Dcompat-mutable-uid-boundaries=true
@@ -1382,6 +1396,8 @@ getent passwd systemd-oom &>/dev/null || useradd -r -l -g systemd-oom -d / -s /s
 
 %files oomd -f .file-list-oomd
 
+%files tests -f .file-list-tests
+
 %clean
 rm -rf $RPM_BUILD_ROOT
 rm -f 10-timeout-abort.conf.user