nxos_vlan: fix broken purge behavior (issue #57101) (#57229)

* nxos_vlan: fix broken purge behavior (issue #57101)

Symptoms/Analysis:
- `nxos_vlan` `purge: true` would fail when `purge` was trying to delete all unspecified vlans, including vlan 1.
- `nxos` devices do not allow removing vlan 1 and raise a cli exception error
- Previous fix #55144 caused a side effect when `purge` was used: vlan changes specified by `aggregate` were ignored; e.g.
 - vlan 4 is not present; playbook specifies `aggregate: { vlan: 4 }, purge: true`
 - results in proper purging but vlan 4 is not created

Solutions:
- ignore vlan 1 when purging
- remove the `not purge` check from state present logic

Added additional unit tests and integration tests.
Tested against all regression platforms.

* PEP fixes

* Add agg_show_vlan_brief.txt fixture

* Add warning for removing vlan 1

* change method name check

test/units/modules/network/nxos/fixtures/nxos_vlan/agg_show_vlan_brief.txt

@@ -0,0 +1,27 @@
+{
+  "TABLE_vlanbriefxbrief": {
+    "ROW_vlanbriefxbrief": [
+      {
+       "vlanshowbr-vlanid": 1,
+       "vlanshowbr-vlanid-utf": 1,
+       "vlanshowbr-vlanname": "default",
+       "vlanshowbr-vlanstate": "active",
+       "vlanshowbr-shutstate": "noshutdown"
+      },
+      {
+       "vlanshowbr-vlanid": 4,
+       "vlanshowbr-vlanid-utf": 4,
+       "vlanshowbr-vlanname": "_4_",
+       "vlanshowbr-vlanstate": "active",
+       "vlanshowbr-shutstate": "noshutdown"
+      },
+      {
+       "vlanshowbr-vlanid": 5,
+       "vlanshowbr-vlanid-utf": 5,
+       "vlanshowbr-vlanname": "_5_",
+       "vlanshowbr-vlanstate": "active",
+       "vlanshowbr-shutstate": "noshutdown"
+      }
+    ]
+  }
+}

test/units/modules/network/nxos/test_nxos_vlan.py

@@ -68,10 +68,84 @@ class TestNxosVlanModule(TestNxosModule):
                 output.append(load_fixture('nxos_vlan', filename))
             return output
 
-        self.run_commands.side_effect = load_from_file
+        def agg_load_from_file(*args, **kwargs):
+            """Load vlan output for aggregate/purge tests"""
+            return([load_fixture('nxos_vlan', 'agg_show_vlan_brief.txt')])
+
+        if '_agg_' in self._testMethodName:
+            self.run_commands.side_effect = agg_load_from_file
+        else:
+            self.run_commands.side_effect = load_from_file
+
         self.load_config.return_value = None
         self.get_config.return_value = load_fixture('nxos_vlan', 'config.cfg')
 
+    def test_nxos_vlan_agg_1(self):
+        # Aggregate: vlan 4/5 exist -> Add 6
+        set_module_args(dict(aggregate=[
+            {'name': '_5_', 'vlan_id': 5},
+            {'name': '_6_', 'vlan_id': 6}
+        ]))
+        self.execute_module(changed=True, commands=[
+            'vlan 6',
+            'name _6_',
+            'state active',
+            'no shutdown',
+            'exit'
+        ])
+
+    def test_nxos_vlan_agg_2(self):
+        # Aggregate: vlan 4/5 exist -> Add none (idempotence)
+        set_module_args(dict(aggregate=[
+            {'name': '_5_', 'vlan_id': 5},
+            {'name': '_4_', 'vlan_id': 4}
+        ]))
+        self.execute_module(changed=False)
+
+    def test_nxos_vlan_agg_3(self):
+        # Aggregate/Purge: vlan 4/5 exist -> Add 6, Purge 4
+        set_module_args(dict(aggregate=[
+            {'name': '_5_', 'vlan_id': 5},
+            {'name': '_6_', 'vlan_id': 6}
+        ], purge=True))
+        self.execute_module(changed=True, commands=[
+            'vlan 6',
+            'name _6_',
+            'state active',
+            'no shutdown',
+            'exit',
+            'no vlan 4'
+        ])
+
+    def test_nxos_vlan_agg_4(self):
+        # Aggregate/Purge: vlan 4/5 exist -> Purge None (idempotence)
+        set_module_args(dict(aggregate=[
+            {'name': '_5_', 'vlan_id': 5},
+            {'name': '_4_', 'vlan_id': 4}
+        ]))
+        self.execute_module(changed=False)
+
+    def test_nxos_vlan_agg_5(self):
+        # Purge with Single Vlan: vlan 4/5 exist -> Add 6, Purge 4/5
+        set_module_args(dict(vlan_id=6, name='_6_', purge=True))
+        self.execute_module(changed=True, commands=[
+            'vlan 6',
+            'name _6_',
+            'state active',
+            'no shutdown',
+            'exit',
+            'no vlan 4',
+            'no vlan 5'
+        ])
+
+    def test_nxos_vlan_agg_6(self):
+        # Purge All: vlan 4/5 exist -> Purge 4/5
+        set_module_args(dict(vlan_id=1, purge=True))
+        self.execute_module(changed=True, commands=[
+            'no vlan 4',
+            'no vlan 5'
+        ])
+
     def test_nxos_vlan_range(self):
         set_module_args(dict(vlan_range='6-10'))
         self.execute_module(changed=True, commands=['vlan 6', 'vlan 7', 'vlan 8', 'vlan 9', 'vlan 10'])