gconftool2: fix change output (#6270)

* gconftool2: fix change output

* add changelog frag

* gconftool2: improve visibility on the output

* fix obtaining updated value after `set`

* use issue URL in the changelog fragment

* fix further issues

* fix return value docs + changelog frag

* Update plugins/modules/gconftool2.py

Co-authored-by: Felix Fontein <felix@fontein.de>

* fix return value doc

---------

Co-authored-by: Felix Fontein <felix@fontein.de>

plugins/modules/gconftool2.py

@@ -35,12 +35,13 @@ options:
     type: str
     description:
     - Preference keys typically have simple values such as strings,
-      integers, or lists of strings and integers. This is ignored if the state
-      is "get". See man gconftool-2(1).
+      integers, or lists of strings and integers.
+      This is ignored unless I(state=present). See man gconftool-2(1).
   value_type:
     type: str
     description:
-    - The type of value being set. This is ignored if the state is "get".
+    - The type of value being set.
+      This is ignored unless I(state=present). See man gconftool-2(1).
     choices: [ bool, float, int, string ]
   state:
     type: str
@@ -56,8 +57,8 @@ options:
       See man gconftool-2(1).
   direct:
     description:
-    - Access the config database directly, bypassing server.  If direct is
-      specified then the config_source must be specified as well.
+    - Access the config database directly, bypassing server.  If I(direct) is
+      specified then the I(config_source) must be specified as well.
       See man gconftool-2(1).
     type: bool
     default: false
@@ -73,17 +74,26 @@ EXAMPLES = """
 
 RETURN = '''
   key:
-    description: The key specified in the module parameters
+    description: The key specified in the module parameters.
     returned: success
     type: str
     sample: /desktop/gnome/interface/font_name
   value_type:
-    description: The type of the value that was changed
+    description: The type of the value that was changed.
     returned: success
     type: str
     sample: string
   value:
-    description: The value of the preference key after executing the module
+    description:
+      - The value of the preference key after executing the module or C(null) if key is removed.
+      - From community.general 7.0.0 onwards it returns C(null) for a non-existent I(key), and returns C("") before that.
+    returned: success
+    type: str
+    sample: "Serif 12"
+  previous_value:
+    description:
+      - The value of the preference key before executing the module.
+      - From community.general 7.0.0 onwards it returns C(null) for a non-existent I(key), and returns C("") before that.
     returned: success
     type: str
     sample: "Serif 12"
@@ -95,7 +105,6 @@ from ansible_collections.community.general.plugins.module_utils.gconftool2 impor
 
 
 class GConftool(StateModuleHelper):
-    change_params = ('value', )
     diff_params = ('value', )
     output_params = ('key', 'value_type')
     facts_params = ('key', 'value_type')
@@ -111,7 +120,6 @@ class GConftool(StateModuleHelper):
         ),
         required_if=[
             ('state', 'present', ['value', 'value_type']),
-            ('state', 'absent', ['value']),
             ('direct', True, ['config_source']),
         ],
         supports_check_mode=True,
@@ -125,6 +133,7 @@ class GConftool(StateModuleHelper):
 
         self.vars.set('previous_value', self._get(), fact=True)
         self.vars.set('value_type', self.vars.value_type)
+        self.vars.set('_value', self.vars.previous_value, output=False, change=True)
         self.vars.set_meta('value', initial_value=self.vars.previous_value)
         self.vars.set('playbook_value', self.vars.value, fact=True)
 
@@ -132,7 +141,8 @@ class GConftool(StateModuleHelper):
         def process(rc, out, err):
             if err and fail_on_err:
                 self.ansible.fail_json(msg='gconftool-2 failed with error: %s' % (str(err)))
-            self.vars.value = out.rstrip()
+            out = out.rstrip()
+            self.vars.value = None if out == "" else out
             return self.vars.value
         return process
 
@@ -148,11 +158,18 @@ class GConftool(StateModuleHelper):
     def state_absent(self):
         with self.runner("state key", output_process=self._make_process(False)) as ctx:
             ctx.run()
+            if self.verbosity >= 4:
+                self.vars.run_info = ctx.run_info
         self.vars.set('new_value', None, fact=True)
+        self.vars._value = None
 
     def state_present(self):
         with self.runner("direct config_source value_type state key value", output_process=self._make_process(True)) as ctx:
-            self.vars.set('new_value', ctx.run(), fact=True)
+            ctx.run()
+            if self.verbosity >= 4:
+                self.vars.run_info = ctx.run_info
+        self.vars.set('new_value', self._get(), fact=True)
+        self.vars._value = self.vars.new_value
 
 
 def main():