From 59c163b6ba3ccffd83620dbd263ce645e161363a Mon Sep 17 00:00:00 2001
From: Marius Rieder <marius.rieder@durchmesser.ch>
Date: Wed, 8 Jun 2022 18:16:40 +0200
Subject: [PATCH] alternatives: Fix bug with priority default

If neigther the priority nor the subcommands where specified the module decided to update the priority with the default value anyway. This resulted in bug #4803 and #4804
---
 plugins/modules/system/alternatives.py             | 10 +++++-----
 .../targets/alternatives/tasks/test.yml            |  2 +-
 .../alternatives/tasks/tests_set_priority.yml      | 14 +++++++++++++-
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/plugins/modules/system/alternatives.py b/plugins/modules/system/alternatives.py
index 1fbc5ccddc2..c05e1248ff3 100644
--- a/plugins/modules/system/alternatives.py
+++ b/plugins/modules/system/alternatives.py
@@ -40,9 +40,8 @@
     type: path
   priority:
     description:
-      - The priority of the alternative.
+      - The priority of the alternative. If no priority is given for creation 50 is used as a fallback.
     type: int
-    default: 50
   state:
     description:
       - C(present) - install the alternative (if not already installed), but do
@@ -171,9 +170,10 @@ def run(self):
         if self.mode_present:
             # Check if we need to (re)install
             subcommands_parameter = self.module.params['subcommands']
+            priority_parameter = self.module.params['priority']
             if (
                 self.path not in self.current_alternatives or
-                self.current_alternatives[self.path].get('priority') != self.priority or
+                (priority_parameter and self.current_alternatives[self.path].get('priority') != priority_parameter) or
                 (subcommands_parameter is not None and (
                     not all(s in subcommands_parameter for s in self.current_alternatives[self.path].get('subcommands')) or
                     not all(s in self.current_alternatives[self.path].get('subcommands') for s in subcommands_parameter)
@@ -273,7 +273,7 @@ def link(self):
 
     @property
     def priority(self):
-        return self.module.params.get('priority')
+        return self.module.params.get('priority') or self.current_alternatives.get(self.path, {}).get('priority') or 50
 
     @property
     def subcommands(self):
@@ -373,7 +373,7 @@ def main():
             name=dict(type='str', required=True),
             path=dict(type='path', required=True),
             link=dict(type='path'),
-            priority=dict(type='int', default=50),
+            priority=dict(type='int'),
             state=dict(
                 type='str',
                 choices=AlternativeState.to_list(),
diff --git a/tests/integration/targets/alternatives/tasks/test.yml b/tests/integration/targets/alternatives/tasks/test.yml
index a5b36ce9224..a4d2f955028 100644
--- a/tests/integration/targets/alternatives/tasks/test.yml
+++ b/tests/integration/targets/alternatives/tasks/test.yml
@@ -48,4 +48,4 @@
   when: ansible_os_family == 'RedHat' and not with_alternatives and item == 1
 
 - name: check that alternative has been updated
-  command: "grep -Pzq '/bin/dummy{{ item }}\\n50' '{{ alternatives_dir }}/dummy'"
+  command: "grep -Pzq '/bin/dummy{{ item }}\\n' '{{ alternatives_dir }}/dummy'"
diff --git a/tests/integration/targets/alternatives/tasks/tests_set_priority.yml b/tests/integration/targets/alternatives/tasks/tests_set_priority.yml
index a629e3f3682..9572a729e75 100644
--- a/tests/integration/targets/alternatives/tasks/tests_set_priority.yml
+++ b/tests/integration/targets/alternatives/tasks/tests_set_priority.yml
@@ -31,4 +31,16 @@
   register: alternative
 
 - name: check that alternative priority has been updated
-  command: "grep -Pzq '/bin/dummy{{ item }}\\n{{ 70 + item|int }}' '{{ alternatives_dir }}/dummy'"
\ No newline at end of file
+  command: "grep -Pzq '/bin/dummy{{ item }}\\n{{ 70 + item|int }}' '{{ alternatives_dir }}/dummy'"
+
+- name: no change without priority
+  alternatives:
+    name: dummy
+    path: '/usr/bin/dummy{{ item }}'
+    link: /usr/bin/dummy
+  register: alternative
+
+- name: check no change was triggerd without priority
+  assert:
+    that:
+      - 'alternative is not changed'