Zypper: Fix update_cache in checkmode (#20143)

Fixes #20139

Refresh does not support dry-run, so don't run it in check mode.
Also add a test for this case.

test/integration/targets/zypper/tasks/zypper.yml

@@ -334,3 +334,27 @@
         - zypperin1|changed
         - not zypperin2|changed
   when: ansible_distribution == 'openSUSE Leap' and ansible_distribution_version == '42.1'
+
+
+# check for https://github.com/ansible/ansible/issues/20139
+- name: run updatecache
+  zypper:
+    name: hello
+    state: present
+    update_cache: True
+  register: zypper_result_update_cache
+
+- name: run updatecache in check mode
+  zypper:
+    name: hello
+    state: present
+    update_cache: True
+  check_mode: True
+  register: zypper_result_update_cache_check
+
+
+- assert:
+    that:
+      - zypper_result_update_cache|success
+      - zypper_result_update_cache_check|success
+      - not zypper_result_update_cache_check|changed