[python] Fix nightly build (#10049)

Tracks
[Azure/typespec-azure#3997](Azure/typespec-azure#3997),
which deprecated `@operationGroup` in favor of `@client` (with flattened
operation hierarchy) and deleted the `multi-service-older-versions`
spec.

### Package update
- Bumped `@azure-tools/azure-http-specs`: `0.1.0-alpha.38` →
`0.1.0-alpha.39-dev.2`

### Deleted tests (spec removed upstream)
- `test_azure_resource_manager_multi_service_older_versions.py` + async
counterpart
- Removed `azure-resource-manager-multi-service-older-versions` from
`requirements.txt`

### Updated tests (reflect flat client hierarchy)

With `@client` replacing `@operationGroup`, sub-groups are no longer
generated — operations are promoted directly onto the parent client:

```python
# Before (with @operationGroup)
client.group3.two()
client.group4.four()
client.group5.six()

# After (with @client — flat)
client.two()
client.four()
client.six()
```

- **`test_client_structure_clientoperationgroup`** + async: removed
`group3`/`group4`/`group5` sub-group access
- **`test_client_structure`** + async: updated `renamed_operation`
(removed `client.group.*`) and `two_operation_group` (removed
`client.group1.*`/`client.group2.*`)
- **`test_client_naming`** + async: `Property` and `Header` namespace
operations now accessed via `client.property.*` and `client.header.*`
sub-groups instead of directly on the root client

<!-- START COPILOT ORIGINAL PROMPT -->



<details>

<summary>Original prompt</summary>

> 
> ----
> 
> *This section details on the original issue you should resolve*
> 
> <issue_title>[python] add test case for
Azure/typespec-azure#3997
> </issue_title>
> <issue_description>follow skill
https://github.com/microsoft/typespec/blob/main/.github/skills/python-sdk-spector-mock-api-tests/SKILL.md
to write test case for Azure/typespec-azure#3997
> </issue_description>
> 
> ## Comments on the Issue (you are @copilot in this section)
> 
> <comments>
> </comments>
> 


</details>



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- Fixes #10048

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Author: Copilot

.chronus/changes/python-test-client-operation-group-to-client-2026-3-16-22-50-0.md

@@ -0,0 +1,7 @@
+---
+changeKind: internal
+packages:
+  - "@typespec/http-client-python"
+---
+
+Update test cases for Azure/typespec-azure#3997: replace `@operationGroup` with `@client` decorator changes. Remove deleted `multi-service-older-versions` tests and update client structure, naming tests to reflect new flat client hierarchy.

packages/http-client-python/.gitignore

@@ -7,3 +7,6 @@ generator/test/.diff-summary.md
 
 # Regeneration marker (tracks when generated code was last regenerated)
 .last-regenerate
+
+# local folder for debug
+alpha

packages/http-client-python/generator/test/azure/mock_api_tests/asynctests/test_azure_resource_manager_multi_service_older_versions_async.py

@@ -16,17 +16,17 @@ async def client():
 
 @pytest.mark.asyncio
 async def test_client(client: NamingClient):
-    await client.client(models.ClientNameModel(client_name=True))
+    await client.property.client(models.ClientNameModel(client_name=True))
 
 
 @pytest.mark.asyncio
 async def test_language(client: NamingClient):
-    await client.language(models.LanguageClientNameModel(python_name=True))
+    await client.property.language(models.LanguageClientNameModel(python_name=True))
 
 
 @pytest.mark.asyncio
 async def test_compatible_with_encoded_name(client: NamingClient):
-    await client.compatible_with_encoded_name(models.ClientNameAndJsonEncodedNameModel(client_name=True))
+    await client.property.compatible_with_encoded_name(models.ClientNameAndJsonEncodedNameModel(client_name=True))
 
 
 @pytest.mark.asyncio
@@ -41,12 +41,12 @@ async def test_parameter(client: NamingClient):
 
 @pytest.mark.asyncio
 async def test_header_request(client: NamingClient):
-    await client.request(client_name="true")
+    await client.header.request(client_name="true")
 
 
 @pytest.mark.asyncio
 async def test_header_response(client: NamingClient):
-    assert (await client.response(cls=lambda x, y, z: z))["default-name"] == "true"
+    assert (await client.header.response(cls=lambda x, y, z: z))["default-name"] == "true"
 
 
 @pytest.mark.asyncio

packages/http-client-python/generator/test/azure/mock_api_tests/asynctests/test_client_naming_async.py

@@ -45,18 +45,18 @@ async def test_structure_renamed_operation():
     await client.renamed_three()
     await client.renamed_five()
 
-    await client.group.renamed_two()
-    await client.group.renamed_four()
-    await client.group.renamed_six()
+    await client.renamed_two()
+    await client.renamed_four()
+    await client.renamed_six()
 
 
 @pytest.mark.asyncio
 async def test_structure_two_operation_group():
-    client = TwoOperationGroupClient(endpoint="http://localhost:3000", client=ClientType.RENAMED_OPERATION)
-    await client.group1.one()
-    await client.group1.three()
-    await client.group1.four()
-
-    await client.group2.two()
-    await client.group2.five()
-    await client.group2.six()
+    client = TwoOperationGroupClient(endpoint="http://localhost:3000", client=ClientType.TWO_OPERATION_GROUP)
+    await client.one()
+    await client.three()
+    await client.four()
+
+    await client.two()
+    await client.five()
+    await client.six()

packages/http-client-python/generator/test/azure/mock_api_tests/asynctests/test_client_structure_async.py

@@ -14,10 +14,10 @@ async def test_first_client_operations():
 
     await client.one()
 
-    await client.group3.two()
-    await client.group3.three()
+    await client.two()
+    await client.three()
 
-    await client.group4.four()
+    await client.four()
 
 
 @pytest.mark.asyncio
@@ -26,4 +26,4 @@ async def test_second_client_operations():
 
     await client.five()
 
-    await client.group5.six()
+    await client.six()

packages/http-client-python/generator/test/azure/mock_api_tests/asynctests/test_client_structure_clientoperationgroup_async.py

@@ -14,15 +14,15 @@ def client():
 
 
 def test_client(client: NamingClient):
-    client.client(models.ClientNameModel(client_name=True))
+    client.property.client(models.ClientNameModel(client_name=True))
 
 
 def test_language(client: NamingClient):
-    client.language(models.LanguageClientNameModel(python_name=True))
+    client.property.language(models.LanguageClientNameModel(python_name=True))
 
 
 def test_compatible_with_encoded_name(client: NamingClient):
-    client.compatible_with_encoded_name(models.ClientNameAndJsonEncodedNameModel(client_name=True))
+    client.property.compatible_with_encoded_name(models.ClientNameAndJsonEncodedNameModel(client_name=True))
 
 
 def test_operation(client: NamingClient):
@@ -34,11 +34,11 @@ def test_parameter(client: NamingClient):
 
 
 def test_header_request(client: NamingClient):
-    client.request(client_name="true")
+    client.header.request(client_name="true")
 
 
 def test_header_response(client: NamingClient):
-    assert client.response(cls=lambda x, y, z: z)["default-name"] == "true"
+    assert client.header.response(cls=lambda x, y, z: z)["default-name"] == "true"
 
 
 def test_model_client(client: NamingClient):

packages/http-client-python/generator/test/azure/mock_api_tests/test_azure_resource_manager_multi_service_older_versions.py

@@ -41,17 +41,17 @@ def test_structure_renamed_operation():
     client.renamed_three()
     client.renamed_five()
 
-    client.group.renamed_two()
-    client.group.renamed_four()
-    client.group.renamed_six()
+    client.renamed_two()
+    client.renamed_four()
+    client.renamed_six()
 
 
 def test_structure_two_operation_group():
     client = TwoOperationGroupClient(endpoint="http://localhost:3000", client=ClientType.TWO_OPERATION_GROUP)
-    client.group1.one()
-    client.group1.three()
-    client.group1.four()
+    client.one()
+    client.three()
+    client.four()
 
-    client.group2.two()
-    client.group2.five()
-    client.group2.six()
+    client.two()
+    client.five()
+    client.six()