[http-client-python] Add XML deserialization tests for EnumerationResults payload

[Copilot]

Adds unit test coverage for deserializing a blob storage-style EnumerationResults XML payload, which exercises several deserialization edge cases in combination: root-element attributes, non-empty text elements, an empty element mapped to a list type, an empty element mapped to a string type, nested empty lists within a container model, and the Azure SDK unwrapped-list pattern.

Changes

• New test TestXmlDeserialization::test_enumeration_results — baseline test with the original payload:

xml_payload = '<?xml version="1.0" encoding="utf-8"?><EnumerationResults ServiceEndpoint="https://service.blob.core.windows.net/" ContainerName="acontainer108f32e8"><Delimiter>/</Delimiter><Blobs /><NextMarker /></EnumerationResults>'
# result.blobs       == []   # <Blobs /> → empty list
# result.next_marker == ""   # <NextMarker /> → empty string

• New test TestXmlDeserialization::test_enumeration_results_nested_empty_list — Blobs is a nested BlobsSegment model with a blob_prefixes: list[BlobPrefix] field (using itemsName wrapper), and the XML has <Blobs><BlobPrefixes /></Blobs>:

# result.blobs.blob_prefixes == []

• New test TestXmlDeserialization::test_enumeration_results_azure_sdk_pattern — follows the real Azure Blob Storage SDK model pattern where BlobsSegment has two unwrapped list fields (blob_prefixes and blob_items) mirroring BlobHierarchyListSegment. With <Blobs />, no matching children exist so both lists are None:

# result.blobs.blob_prefixes is None   # unwrapped empty list → None
# result.blobs.blob_items    is None   # unwrapped empty list → None

• New test TestXmlDeserialization::test_enumeration_results_blobs_unwrapped — documents the behavior when a model-typed field is annotated with unwrapped=True: the deserialization enters the unwrapped-list branch and stores the collected ET.Element objects as-is, returning a list[ET.Element] instead of the expected model instance.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[http-client-python] model base deserialization</issue_title>
<issue_description>Can we add a new test for deserializing the following xml payload:

<?xml version="1.0" encoding="utf-8"?><EnumerationResults ServiceEndpoint="https://service.blob.core.windows.net/" ContainerName="acontainer108f32e8"><Delimiter>/</Delimiter><Blobs /><NextMarker /></EnumerationResults></issue_description>

<agent_instructions>to the http-client-python package</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes [http-client-python] model base deserialization #9777

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commit: bd1f951

[l0lawrence]

@copilot what if the model we are deserializing could potential have a list of lists and both are empty, like blobs contains blobprefixes which expects an empty list

[l0lawrence]

@copilot like if our enumerationResults model followed this model pattern -- https://github.com/l0lawrence/azure-sdk-for-python/blob/14028a4655c9055e234fb142a91da64fdd0b82f4/sdk/storage/azure-storage-blob/azure/storage/blob/_generated/models/_models_py3.py#L1566

[Copilot]

Added test_enumeration_results_nested_empty_list in commit 833e54e. It uses XML <Blobs><BlobPrefixes /></Blobs> where blobs is a BlobsSegment model containing blob_prefixes: list[BlobPrefix]. The test asserts that result.blobs.blob_prefixes == [] — an empty <BlobPrefixes /> element inside a container correctly deserializes to an empty list.

[Copilot]

Added test_enumeration_results_azure_sdk_pattern in commit 8caa873. It follows the linked Azure SDK model — BlobsSegment has both blob_prefixes: list[BlobPrefix] (unwrapped) and blob_items: list[BlobItem] (unwrapped). With <Blobs />, no matching children are found so both lists are None.

[l0lawrence]

@copilot what if blobs is xml.unwrapped True

[Copilot]

Added test_enumeration_results_blobs_unwrapped in commit 8caa873. When a model-typed field (blobs: BlobsSegment) has unwrapped=True, the deserialization enters the unwrapped-list branch and stores the collected XML elements as-is — result.blobs becomes a list[ET.Element] instead of a BlobsSegment instance. The test documents this current behavior.

[l0lawrence]

do we want this to be None?