snap: fix case when snap list is empty (#7124)

* fix case when snap list is empty

* add changelog frag

changelogs/fragments/7124-snap-empty-list.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - snap - an exception was being raised when snap list was empty (https://github.com/ansible-collections/community.general/pull/7124, https://github.com/ansible-collections/community.general/issues/7120).

plugins/modules/snap.py

@@ -326,6 +326,8 @@ class Snap(StateModuleHelper):
                                                               if x.startswith("warning: no snap found")]))
             return process_(rc, out, err)
 
+        names = []
+        if snaps:
             with self.runner("info name", output_process=process) as ctx:
                 try:
                     names = ctx.run(name=snaps)

tests/integration/targets/snap/tasks/main.yml

@@ -19,3 +19,5 @@
       ansible.builtin.include_tasks: test_dangerous.yml
     - name: Include test_3dash
       ansible.builtin.include_tasks: test_3dash.yml
+    - name: Include test_empty_list
+      ansible.builtin.include_tasks: test_empty_list.yml

tests/integration/targets/snap/tasks/test_empty_list.yml

@@ -0,0 +1,14 @@
+---
+# Copyright (c) Ansible Project
+# GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+- name: Empty list present
+  community.general.snap:
+    name: []
+    state: present
+
+- name: Empty list absent
+  community.general.snap:
+    name: []
+    state: absent