feat(http-client-python): add mock API tests for reserved operation body param names

.chronus/changes/python-reserved-operation-body-params-test-2026-4-28-23-10-0.md

@@ -0,0 +1,7 @@
+---
+changeKind: internal
+packages:
+  - "@typespec/http-client-python"
+---
+
+Add mock API test cases for operation body parameters with reserved names (e.g., `items`) to verify the wire name is not mangled.

packages/http-client-python/tests/mock_api/azure/asynctests/test_special_words_async.py

@@ -70,3 +70,8 @@ async def test_model_properties_with_list(client: SpecialWordsClient):
 async def test_extensible_strings(client: SpecialWordsClient):
     for enum_value in models.ExtensibleString:
         assert enum_value == await client.extensible_strings.put_extensible_string_value(body=enum_value)
+
+
+@pytest.mark.asyncio
+async def test_reserved_operation_body_params_with_items(client: SpecialWordsClient):
+    await client.reserved_operation_body_params.with_items(items=["item"])

packages/http-client-python/tests/mock_api/azure/test_special_words.py

@@ -61,3 +61,7 @@ def test_model_properties_with_list(client: SpecialWordsClient):
 def test_extensible_strings(client: SpecialWordsClient):
     for enum_value in models.ExtensibleString:
         assert enum_value == client.extensible_strings.put_extensible_string_value(body=enum_value)
+
+
+def test_reserved_operation_body_params_with_items(client: SpecialWordsClient):
+    client.reserved_operation_body_params.with_items(items=["item"])

packages/http-client-python/tests/mock_api/unbranded/asynctests/test_special_words_async.py

@@ -72,3 +72,8 @@ async def test_model_properties_with_list(client: SpecialWordsClient):
 async def test_extensible_strings(client: SpecialWordsClient):
     for enum_value in extensible_strings_models.ExtensibleString:
         assert enum_value == await client.extensible_strings.put_extensible_string_value(body=enum_value)
+
+
+@pytest.mark.asyncio
+async def test_reserved_operation_body_params_with_items(client: SpecialWordsClient):
+    await client.reserved_operation_body_params.with_items(items=["item"])

packages/http-client-python/tests/mock_api/unbranded/test_special_words.py

@@ -64,3 +64,7 @@ def test_model_properties_with_list(client: SpecialWordsClient):
 def test_extensible_strings(client: SpecialWordsClient):
     for enum_value in extensible_strings_models.ExtensibleString:
         assert enum_value == client.extensible_strings.put_extensible_string_value(body=enum_value)
+
+
+def test_reserved_operation_body_params_with_items(client: SpecialWordsClient):
+    client.reserved_operation_body_params.with_items(items=["item"])