test(http-client-python): cover json overload when typeddict is disabled

Co-authored-by: l0lawrence <100643745+l0lawrence@users.noreply.github.com>

Author: Copilot

packages/http-client-python/generator/pygen/preprocess/__init__.py

@@ -94,7 +94,8 @@ def add_overloads_for_body_param(yaml_data: dict[str, Any]) -> None:
             continue
         if body_type.get("type") == "model" and body_type.get("base") == "json":
             yaml_data["overloads"].append(add_overload(yaml_data, body_type, for_flatten_params=True))
-            # Skip single-body JSON overload; the TypedDict overload replaces it
+            # Use the flattened JSON overload and skip the single-body JSON overload.
+            # When TypedDict generation is disabled, this JSON overload remains.
             continue
         yaml_data["overloads"].append(add_overload(yaml_data, body_type))
     content_type_param = next(p for p in yaml_data["parameters"] if p["wireName"].lower() == "content-type")

packages/http-client-python/tests/unit/test_typeddict_overloads.py

@@ -119,6 +119,32 @@ def test_dpg_mode_can_disable_typeddict_autogeneration():
     assert not any(t for t in code_model["types"] if t.get("base") == "typeddict")
 
 
+def test_spread_body_opt_out_keeps_json_overload():
+    """Spread bodies keep the flattened JSON overload when TypedDict generation is disabled."""
+    plugin = _plugin("dpg", **{"generate-typeddict": False})
+    spread_body = _json_spread_body_parameter("CreateRequest", "Contoso.Widget")
+    yaml_data = {
+        "name": "create",
+        "bodyParameter": spread_body,
+        "parameters": [_content_type_param()],
+        "overloads": [],
+        "responses": [],
+        "exceptions": [],
+    }
+    code_model = {"types": [spread_body["type"]]}
+
+    plugin.add_body_param_type(code_model, spread_body)
+    add_overloads_for_body_param(yaml_data)
+
+    assert spread_body["type"]["type"] == "combined"
+    assert spread_body["type"]["types"][0]["base"] == "json"
+    assert spread_body["type"]["types"][1] == {"type": "binary"}
+    assert len(yaml_data["overloads"]) == 2
+    json_overload = next(o for o in yaml_data["overloads"] if o["bodyParameter"]["type"].get("base") == "json")
+    assert json_overload["bodyParameter"]["flattened"] is True
+    assert not any(t for t in code_model["types"] if t.get("base") == "typeddict")
+
+
 def _dpg_body_parameter(name: str, cross_lang_id: str) -> dict:
     """A JSON dpg-model body parameter for the given model name and cross-language id."""
     model_type = {