Fix : awx.awx.group preserve hosts fails when there are no hosts (#13913)

Co-authored-by: Sean Sullivan <ssulliva@redhat.com>

awx_collection/plugins/modules/group.py

@@ -170,9 +170,11 @@ def main():
             id_list.append(sub_obj['id'])
         # Preserve existing objects
         if (preserve_existing_hosts and relationship == 'hosts') or (preserve_existing_children and relationship == 'children'):
-            preserve_existing_check = module.get_all_endpoint(group['related'][relationship])
-            for sub_obj in preserve_existing_check['json']['results']:
-                id_list.append(sub_obj['id'])
+            if group:
+                preserve_existing_check = module.get_all_endpoint(group['related'][relationship])
+                for sub_obj in preserve_existing_check['json']['results']:
+                    if 'id' in sub_obj:
+                        id_list.append(sub_obj['id'])
         if id_list:
             association_fields[relationship] = id_list
 

awx_collection/tests/integration/targets/group/tasks/main.yml

@@ -9,10 +9,12 @@
     group_name1: "AWX-Collection-tests-group-group1-{{ test_id }}"
     group_name2: "AWX-Collection-tests-group-group2-{{ test_id }}"
     group_name3: "AWX-Collection-tests-group-group3-{{ test_id }}"
+    group_name4: "AWX-Collection-tests-group-group4-{{ test_id }}"
     inv_name: "AWX-Collection-tests-group-inv-{{ test_id }}"
     host_name1: "AWX-Collection-tests-group-host1-{{ test_id }}"
     host_name2: "AWX-Collection-tests-group-host2-{{ test_id }}"
     host_name3: "AWX-Collection-tests-group-host3-{{ test_id }}"
+    host_name4: "AWX-Collection-tests-group-host4-{{ test_id }}"
 
 - name: Create an Inventory
   inventory:
@@ -21,6 +23,26 @@
     state: present
   registuer: result
 
+- name: Create a Host
+  host:
+    name: "{{ host_name4 }}"
+    inventory: "{{ inv_name }}"
+    state: present
+  register: result
+
+- name: Add Host to Group
+  group:
+    name: "{{ group_name1 }}"
+    inventory: "{{ inv_name }}"
+    hosts:
+      - "{{ host_name4 }}"
+    preserve_existing_hosts: true
+  register: result
+
+- assert:
+    that:
+      - "result is changed"
+
 - name: Create Group 1
   group:
     name: "{{ group_name1 }}"