Fix idempotency for empty values (#790)

Fix #788
Signed-off-by: Sagi Shnaidman <sshnaidm@redhat.com>

plugins/module_utils/podman/common.py

@@ -404,11 +404,15 @@ def diff_generic(params, info_config, module_arg, cmd_arg, boolean_type=False):
             after = ",".join(sorted([str(i).lower() for i in after]))
             if before:
                 before = ",".join(sorted([str(i).lower() for i in before]))
+            else:
+                before = ''
         elif isinstance(after, dict):
             after = ",".join(sorted(
                 [str(k).lower() + "=" + str(v).lower() for k, v in after.items() if v is not None]))
             if before:
                 before = ",".join(sorted([j.lower() for j in before]))
+            else:
+                before = ''
         elif isinstance(after, bool):
             after = str(after).capitalize()
             if before is not None:

tests/integration/targets/podman_container_idempotency/tasks/idem_all.yml

@@ -26,6 +26,44 @@
   assert:
     that: test1 is not changed
 
+- name: Run container with empty vars for list and dict
+  containers.podman.podman_container:
+    executable: "{{ test_executable | default('podman') }}"
+    image: "{{ idem_image }}"
+    name: idempotency
+    state: present
+    env: {}
+    publish: []
+    command: 1h
+  register: test_to_empty
+
+- name: Run container with empty vars for list and dict - again
+  containers.podman.podman_container:
+    executable: "{{ test_executable | default('podman') }}"
+    image: "{{ idem_image }}"
+    name: idempotency
+    state: present
+    env: {}
+    publish: []
+    command: 1h
+  register: test_empty
+
+- name: Run container again w/o empty vars
+  containers.podman.podman_container:
+    executable: "{{ test_executable | default('podman') }}"
+    image: "{{ idem_image }}"
+    name: idempotency
+    state: present
+    command: 1h
+  register: test_from_empty
+
+- name: Check info when running container again
+  assert:
+    that:
+      - test_to_empty is not changed
+      - test_empty is not changed
+      - test_from_empty is not changed
+
 - name: Run container with environment vars
   containers.podman.podman_container:
     executable: "{{ test_executable | default('podman') }}"