From 5f2c428d1cbe8fd814a887bf5286c4912af3c71e Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 29 Sep 2026 05:22:12 +0000
Subject: [PATCH 1/2] Initial plan


From edc54f38308811548aa52f1ea85ae5269c8b5423 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 29 Sep 2026 05:26:12 +0000
Subject: [PATCH 2/2] test(python): assert alternate types deserialize to
 GeoJSON Features

Co-authored-by: msyyc <70930885+msyyc@users.noreply.github.com>
---
 .../changes/python-alternate-type-test-2026-9-29-5-24-0.md | 7 +++++++
 ...est_azure_client_generator_core_alternate_type_async.py | 2 ++
 .../test_azure_client_generator_core_alternate_type.py     | 2 ++
 3 files changed, 11 insertions(+)
 create mode 100644 .chronus/changes/python-alternate-type-test-2026-9-29-5-24-0.md

diff --git a/.chronus/changes/python-alternate-type-test-2026-9-29-5-24-0.md b/.chronus/changes/python-alternate-type-test-2026-9-29-5-24-0.md
new file mode 100644
index 00000000000..0a37fb768e2
--- /dev/null
+++ b/.chronus/changes/python-alternate-type-test-2026-9-29-5-24-0.md
@@ -0,0 +1,7 @@
+---
+changeKind: internal
+packages:
+  - "@typespec/http-client-python"
+---
+
+Assert alternate-type responses are deserialized as `geojson.Feature` in sync and async mock API tests.
diff --git a/packages/http-client-python/tests/mock_api/azure/asynctests/test_azure_client_generator_core_alternate_type_async.py b/packages/http-client-python/tests/mock_api/azure/asynctests/test_azure_client_generator_core_alternate_type_async.py
index 30f453723e1..31f286792b5 100644
--- a/packages/http-client-python/tests/mock_api/azure/asynctests/test_azure_client_generator_core_alternate_type_async.py
+++ b/packages/http-client-python/tests/mock_api/azure/asynctests/test_azure_client_generator_core_alternate_type_async.py
@@ -34,6 +34,7 @@ async def test_external_type_get_model(client: AlternateTypeClient):
     """Test getting a Feature object with geometry, properties, and optional id fields."""
     result = await client.external_type.get_model()
 
+    assert isinstance(result, geojson.Feature)
     # Validate the response structure based on the TypeSpec example
     assert result.type == "Feature"
     assert result.geometry.type == "Point"
@@ -55,6 +56,7 @@ async def test_external_type_get_property(client: AlternateTypeClient):
     """Test getting a ModelWithFeatureProperty object with feature and additionalProperty fields."""
     result = await client.external_type.get_property()
 
+    assert isinstance(result.feature, geojson.Feature)
     # Validate the response structure based on the TypeSpec example
     assert result.feature.type == "Feature"
     assert result.feature.geometry.type == "Point"
diff --git a/packages/http-client-python/tests/mock_api/azure/test_azure_client_generator_core_alternate_type.py b/packages/http-client-python/tests/mock_api/azure/test_azure_client_generator_core_alternate_type.py
index c5ae3266c87..278333d1ceb 100644
--- a/packages/http-client-python/tests/mock_api/azure/test_azure_client_generator_core_alternate_type.py
+++ b/packages/http-client-python/tests/mock_api/azure/test_azure_client_generator_core_alternate_type.py
@@ -32,6 +32,7 @@ def test_external_type_get_model(client: AlternateTypeClient):
     """Test getting a Feature object with geometry, properties, and optional id fields."""
     result = client.external_type.get_model()
 
+    assert isinstance(result, geojson.Feature)
     # Validate the response structure based on the TypeSpec example
     assert result.type == "Feature"
     assert result.geometry.type == "Point"
@@ -51,6 +52,7 @@ def test_external_type_get_property(client: AlternateTypeClient):
     """Test getting a ModelWithFeatureProperty object with feature and additionalProperty fields."""
     result = client.external_type.get_property()
 
+    assert isinstance(result.feature, geojson.Feature)
     # Validate the response structure based on the TypeSpec example
     assert result.feature.type == "Feature"
     assert result.feature.geometry.type == "Point"