Fix `vyos.vyos.vyos_firewall_rules` `state: replaced` to match documentation (#203)

Fix `vyos.vyos.vyos_firewall_rules` `state: replaced` to match documentation

SUMMARY
vyos.vyos.vyos_firewall_rules should only try to change listed firewall rules, as documented, when the state is set to replaced.  As currently implemented (prior to this PR), it better matches what overridden is meant to do.
Fixes #201
ISSUE TYPE


Bugfix Pull Request

COMPONENT NAME
vyos.vyos.vyos_firewall_rules
ADDITIONAL INFORMATION

 Cleanup and document existing code for clarity
 Add a failing idempotent test
 Add a failing change test
 Fix failing tests
 Add change fragment

Reviewed-by: GomathiselviS <None>
Reviewed-by: Shawn Wilsher <None>
Reviewed-by: None <None>

1 files changed, 19 insertions, 3 deletions

diff --git a/plugins/module_utils/network/vyos/config/firewall_rules/firewall_rules.py b/plugins/module_utils/network/vyos/config/firewall_rules/firewall_rules.py
index fd5a4f5..3c56626 100644
--- a/plugins/module_utils/network/vyos/config/firewall_rules/firewall_rules.py
+++ b/plugins/module_utils/network/vyos/config/firewall_rules/firewall_rules.py
@@ -167,13 +167,29 @@ class Firewall_rules(ConfigBase):
         """
         commands = []
         if have:
+            # Iterate over the afi rule sets we already have.
             for h in have:
                 r_sets = self._get_r_sets(h)
+                # Iterate over each rule set we already have.
                 for rs in r_sets:
-                    w = self.search_r_sets_in_have(want, rs["name"], "r_list")
-                    commands.extend(
-                        self._add_r_sets(h["afi"], rs, w, opr=False)
+                    # In the desired configuration, search for the rule set we
+                    # already have (to be replaced by our desired
+                    # configuration's rule set).
+                    wanted_rule_set = self.search_r_sets_in_have(
+                        want, rs["name"], "r_list"
                     )
+                    if wanted_rule_set is not None:
+                        # Remove the rules that we already have if the wanted
+                        # rules exist under the same name.
+                        commands.extend(
+                            self._add_r_sets(
+                                h["afi"],
+                                want=rs,
+                                have=wanted_rule_set,
+                                opr=False,
+                            )
+                        )
+        # Merge the desired configuration into what we already have.
         commands.extend(self._state_merged(want, have))
         return commands