[Resource] Clarify provider registration subscription scope

src/azure-cli/azure/cli/command_modules/resource/_help.py

@@ -1747,11 +1747,17 @@
 helps['provider register'] = """
 type: command
 short-summary: Register a provider.
+long-summary: By default, this command registers the provider in the current default subscription. Use
+    `--subscription` or `az account set` to change the default subscription when you need to target
+    another one.
 examples:
   - name: Register a provider. (autogenerated)
     text: |
         az provider register --namespace 'Microsoft.PolicyInsights'
     crafted: true
+  - name: Register a provider for a specific subscription.
+    text: |
+        az provider register --namespace Microsoft.CognitiveServices --subscription 12345678-1234-1234-1234-123456789012
   - name: Register a provider from RPaaS.
     text: |
         az provider register -n 'Microsoft.Confluent' --accept-terms

src/azure-cli/azure/cli/command_modules/resource/custom.py

@@ -3459,14 +3459,18 @@ def list_features(client, resource_provider_namespace=None):
 
 
 def register_feature(client, resource_provider_namespace, feature_name):
-    logger.warning("Once the feature '%s' is registered, invoking 'az provider register -n %s' is required "
-                   "to get the change propagated", feature_name, resource_provider_namespace)
+    logger.warning("Once the feature '%s' is registered, invoke 'az provider register -n %s' in the current "
+                   "default subscription to get the change propagated. Use '--subscription' or "
+                   "'az account set' to change the default subscription if you need to target another one.",
+                   feature_name, resource_provider_namespace)
     return client.register(resource_provider_namespace, feature_name)
 
 
 def unregister_feature(client, resource_provider_namespace, feature_name):
-    logger.warning("Once the feature '%s' is unregistered, invoking 'az provider register -n %s' is required "
-                   "to get the change propagated", feature_name, resource_provider_namespace)
+    logger.warning("Once the feature '%s' is unregistered, invoke 'az provider register -n %s' in the current "
+                   "default subscription to get the change propagated. Use '--subscription' or "
+                   "'az account set' to change the default subscription if you need to target another one.",
+                   feature_name, resource_provider_namespace)
     return client.unregister(resource_provider_namespace, feature_name)
 
 

src/azure-cli/azure/cli/command_modules/resource/tests/latest/test_resource_custom.py

@@ -31,7 +31,10 @@
     publish_bicep_file,
     _process_template_file,
     _prepare_deployment_properties_unmodified,
+    register_feature,
+    unregister_feature,
 )
+from azure.cli.command_modules.resource._help import helps
 
 from azure.cli.command_modules.resource._bicep import (run_bicep_command)
 
@@ -252,6 +255,34 @@ def prompt_function(x):
         with self.assertRaisesRegex(CLIError, "Missing input parameters: missing"):
             _get_missing_parameters(parameters, template, prompt_function)
 
+    @mock.patch('azure.cli.command_modules.resource.custom.logger.warning')
+    def test_feature_registration_warning_mentions_subscription_scope(self, logger_warning):
+        feature_name = 'TestFeature'
+        for method_name, operation in [('register', register_feature), ('unregister', unregister_feature)]:
+            with self.subTest(method_name=method_name):
+                logger_warning.reset_mock()
+                client = mock.Mock()
+                expected = object()
+                getattr(client, method_name).return_value = expected
+
+                result = operation(client, 'Microsoft.CognitiveServices', feature_name)
+
+                self.assertIs(result, expected)
+                getattr(client, method_name).assert_called_once_with(
+                    'Microsoft.CognitiveServices', feature_name)
+                logger_warning.assert_called_once()
+                warning_message = logger_warning.call_args.args[0]
+                self.assertIn('current default subscription', warning_message)
+                self.assertIn('--subscription', warning_message)
+                self.assertIn('az account set', warning_message)
+
+    def test_provider_register_help_mentions_subscription_scope(self):
+        self.assertIn('provider register', helps)
+        help_text = helps['provider register']
+        self.assertIn('current default subscription', help_text)
+        self.assertIn('`--subscription`', help_text)
+        self.assertIn('Microsoft.CognitiveServices --subscription', help_text)
+
     def test_deployment_parameters(self):
 
         curr_dir = os.path.dirname(os.path.realpath(__file__))