Add partial diff support, not in check mode to openbsd_pkg (#8402)

* Add partial diff support, not in check mode

* Add changelog fragment

* Fix PEP8. Want to run Black against this so badly.

* Update changelogs/fragments/8402-add-diif-mode-openbsd-pkg.yml

Co-authored-by: Felix Fontein <felix@fontein.de>

* Update plugins/modules/openbsd_pkg.py

Co-authored-by: Felix Fontein <felix@fontein.de>

* Update plugins/modules/openbsd_pkg.py

Co-authored-by: Felix Fontein <felix@fontein.de>

* Remove unneeded comment

---------

Co-authored-by: Allen Smith <allsmith@allsmith.users.ipa.redhat.com>
Co-authored-by: Felix Fontein <felix@fontein.de>

changelogs/fragments/8402-add-diif-mode-openbsd-pkg.yml

@@ -0,0 +1,2 @@
+minor_changes:
+    - openbsd_pkg - adds diff support to show changes in installed package list. This does not yet work for check mode (https://github.com/ansible-collections/community.general/pull/8402).

plugins/modules/openbsd_pkg.py

@@ -24,7 +24,10 @@ attributes:
     check_mode:
         support: full
     diff_mode:
-        support: none
+        support: partial
+        version_added: 9.1.0
+        details:
+          - Only works when check mode is not enabled.
 options:
     name:
         description:
@@ -159,6 +162,20 @@ def execute_command(cmd, module):
     return module.run_command(cmd_args, environ_update={'TERM': 'dumb'})
 
 
+def get_all_installed(module):
+    """
+    Get all installed packaged. Used to support diff mode
+    """
+    command = 'pkg_info -Iq'
+
+    rc, stdout, stderr = execute_command(command, module)
+
+    if stderr:
+        module.fail_json(msg="failed in get_all_installed(): %s" % stderr)
+
+    return stdout
+
+
 # Function used to find out if a package is currently installed.
 def get_package_state(names, pkg_spec, module):
     info_cmd = 'pkg_info -Iq'
@@ -573,10 +590,13 @@ def main():
     result['name'] = name
     result['state'] = state
     result['build'] = build
+    result['diff'] = {}
 
     # The data structure used to keep track of package information.
     pkg_spec = {}
 
+    new_package_list = original_package_list = get_all_installed(module)
+
     if build is True:
         if not os.path.isdir(ports_dir):
             module.fail_json(msg="the ports source directory %s does not exist" % (ports_dir))
@@ -661,6 +681,10 @@ def main():
 
     result['changed'] = combined_changed
 
+    if result['changed'] and not module.check_mode:
+        new_package_list = get_all_installed(module)
+        result['diff'] = dict(before=original_package_list, after=new_package_list)
+
     module.exit_json(**result)