Python: Improve hashing of cmc and scmc items. Add tests. (#10332)

### Motivation and Context

We have some content types that can't be hashed as-is. This PR makes
sure that if there are unhashable types, that we turn them into hashable
types. Add unit tests to exercise the scenarios.

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### Description

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### Contribution Checklist

<!-- Before submitting this PR, please make sure: -->

- [X] The code builds clean without any errors or warnings
- [X] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [X] All unit tests pass, and I have added new tests where possible
- [X] I didn't break anyone 😄

python/semantic_kernel/contents/chat_message_content.py

@@ -33,6 +33,7 @@
 from semantic_kernel.contents.text_content import TextContent
 from semantic_kernel.contents.utils.author_role import AuthorRole
 from semantic_kernel.contents.utils.finish_reason import FinishReason
+from semantic_kernel.contents.utils.hashing import make_hashable
 from semantic_kernel.exceptions.content_exceptions import ContentInitializationError
 
 TAG_CONTENT_MAP = {
@@ -315,4 +316,5 @@ def _parse_items(self) -> str | list[dict[str, Any]]:
 
     def __hash__(self) -> int:
         """Return the hash of the chat message content."""
-        return hash((self.tag, self.role, self.content, self.encoding, self.finish_reason, *self.items))
+        hashable_items = [make_hashable(item) for item in self.items] if self.items else []
+        return hash((self.tag, self.role, self.content, self.encoding, self.finish_reason, *hashable_items))

python/semantic_kernel/contents/streaming_chat_message_content.py

@@ -16,6 +16,7 @@
 from semantic_kernel.contents.streaming_text_content import StreamingTextContent
 from semantic_kernel.contents.utils.author_role import AuthorRole
 from semantic_kernel.contents.utils.finish_reason import FinishReason
+from semantic_kernel.contents.utils.hashing import make_hashable
 from semantic_kernel.exceptions import ContentAdditionException
 
 ITEM_TYPES = Union[
@@ -222,6 +223,7 @@ def to_element(self) -> "Element":
 
     def __hash__(self) -> int:
         """Return the hash of the streaming chat message content."""
+        hashable_items = [make_hashable(item) for item in self.items] if self.items else []
         return hash((
             self.tag,
             self.role,
@@ -230,5 +232,5 @@ def __hash__(self) -> int:
             self.finish_reason,
             self.choice_index,
             self.function_invoke_attempt,
-            *self.items,
+            *hashable_items,
         ))

python/tests/unit/contents/test_chat_message_content.py

@@ -4,6 +4,7 @@
 from defusedxml.ElementTree import XML
 
 from semantic_kernel.contents.chat_message_content import ChatMessageContent
+from semantic_kernel.contents.file_reference_content import FileReferenceContent
 from semantic_kernel.contents.function_call_content import FunctionCallContent
 from semantic_kernel.contents.function_result_content import FunctionResultContent
 from semantic_kernel.contents.image_content import ImageContent
@@ -380,3 +381,37 @@ def test_cmc_to_dict_keys():
 def test_cmc_to_dict_items(input_args, expected_dict):
     message = ChatMessageContent(**input_args)
     assert message.to_dict() == expected_dict
+
+
+def test_cmc_with_unhashable_types_can_hash():
+    user_messages = [
+        ChatMessageContent(
+            role=AuthorRole.USER,
+            items=[
+                TextContent(text="Describe this image."),
+                ImageContent(
+                    uri="https://upload.wikimedia.org/wikipedia/commons/thumb/4/47/New_york_times_square-terabass.jpg/1200px-New_york_times_square-terabass.jpg"
+                ),
+            ],
+        ),
+        ChatMessageContent(
+            role=AuthorRole.USER,
+            items=[
+                TextContent(text="What is the main color in this image?"),
+                ImageContent(uri="https://upload.wikimedia.org/wikipedia/commons/5/56/White_shark.jpg"),
+            ],
+        ),
+        ChatMessageContent(
+            role=AuthorRole.USER,
+            items=[
+                TextContent(text="Is there an animal in this image?"),
+                FileReferenceContent(file_id="test_file_id"),
+            ],
+        ),
+        ChatMessageContent(
+            role=AuthorRole.USER,
+        ),
+    ]
+
+    for message in user_messages:
+        assert hash(message) is not None

python/tests/unit/contents/test_streaming_chat_message_content.py

@@ -4,8 +4,10 @@
 from defusedxml.ElementTree import XML
 
 from semantic_kernel.contents.chat_message_content import ChatMessageContent
+from semantic_kernel.contents.file_reference_content import FileReferenceContent
 from semantic_kernel.contents.function_call_content import FunctionCallContent
 from semantic_kernel.contents.function_result_content import FunctionResultContent
+from semantic_kernel.contents.image_content import ImageContent
 from semantic_kernel.contents.streaming_chat_message_content import StreamingChatMessageContent
 from semantic_kernel.contents.streaming_text_content import StreamingTextContent
 from semantic_kernel.contents.text_content import TextContent
@@ -410,3 +412,41 @@ def test_scmc_bytes():
     message = StreamingChatMessageContent(choice_index=0, role=AuthorRole.USER, content="Hello, world!")
     assert bytes(message) == b"Hello, world!"
     assert bytes(message.items[0]) == b"Hello, world!"
+
+
+def test_scmc_with_unhashable_types_can_hash():
+    user_messages = [
+        StreamingChatMessageContent(
+            role=AuthorRole.USER,
+            items=[
+                StreamingTextContent(text="Describe this image.", choice_index=0),
+                ImageContent(
+                    uri="https://upload.wikimedia.org/wikipedia/commons/thumb/4/47/New_york_times_square-terabass.jpg/1200px-New_york_times_square-terabass.jpg"
+                ),
+            ],
+            choice_index=0,
+        ),
+        StreamingChatMessageContent(
+            role=AuthorRole.USER,
+            items=[
+                StreamingTextContent(text="What is the main color in this image?", choice_index=0),
+                ImageContent(uri="https://upload.wikimedia.org/wikipedia/commons/5/56/White_shark.jpg"),
+            ],
+            choice_index=0,
+        ),
+        StreamingChatMessageContent(
+            role=AuthorRole.USER,
+            items=[
+                StreamingTextContent(text="Is there an animal in this image?", choice_index=0),
+                FileReferenceContent(file_id="test_file_id"),
+            ],
+            choice_index=0,
+        ),
+        StreamingChatMessageContent(
+            role=AuthorRole.USER,
+            choice_index=0,
+        ),
+    ]
+
+    for message in user_messages:
+        assert hash(message) is not None