Arbiter change and test additions (#59883)

lib/ansible/modules/database/mongodb/mongodb_replicaset.py

@@ -333,7 +333,7 @@ def main():
     if validate:
         if len(members) <= 2 or len(members) % 2 == 0:
             module.fail_json(msg="MongoDB Replicaset validation failed. Invalid number of replicaset members.")
-        if arbiter_at_index is not None and len(members) - 1 > arbiter_at_index:
+        if arbiter_at_index is not None and len(members) - 1 < arbiter_at_index:
             module.fail_json(msg="MongoDB Replicaset validation failed. Invalid arbiter index.")
 
     result = dict(

test/integration/targets/mongodb_replicaset/tasks/main.yml

@@ -493,4 +493,48 @@
 #      - "'Name or service not known' in host_does_not_exist.module_stderr"
 
 # Final clean up to prevent "directory not empty" error
+
+# Test invalid arbiter handling
+# Test with arbiter_at_index
+- name: Test invalid arbiter handling 1
+  mongodb_replicaset:
+    login_user: admin
+    login_password: secret
+    login_host: "localhost"
+    login_port: 3001
+    login_database: "admin"
+    arbiter_at_index: 0
+    replica_set: "{{ mongodb_replicaset4 }}"
+    members:
+      - localhost:3001
+      - localhost:3002
+      - localhost:3003
+      - localhost:3004
+  ignore_errors: yes
+  register: invalid_num
+
+- assert:
+    that:
+      - "'MongoDB Replicaset validation failed. Invalid number of replicaset members.' == invalid_num.msg"
+
+- name: Test invalid arbiter handling 2
+  mongodb_replicaset:
+    login_user: admin
+    login_password: secret
+    login_host: "localhost"
+    login_port: 3001
+    login_database: "admin"
+    arbiter_at_index: 4
+    replica_set: "{{ mongodb_replicaset4 }}"
+    members:
+      - localhost:3001
+      - localhost:3002
+      - localhost:3003
+  ignore_errors: yes
+  register: invalid_num2
+
+- assert:
+    that:
+      - "'MongoDB Replicaset validation failed. Invalid arbiter index.' == invalid_num2.msg"
+
 - include_tasks: mongod_teardown.yml