Python: Fix KernelArgument bug in invoke_prompt functions (#8414)

### Motivation and Context

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In `invoke_prompt(...)` and `invoke_prompt_async(...)`, the `arguments`
parameter is tested to see if it's empty before proceeding. The type of
the `arguments` parameter is `KernelArgument`, which derives from a
`dict` type, with an additional field for execution settings. When
`arguments` contains only the execution settings, it will be considered
as an empty dictionary. This will result in the `arguments` parameter
being overridden completely, invalidating all execution settings passed
to the APIs.

To reproduce (assuming we have a plugin/function that will return the
weather):
```
result = await kernel.invoke_prompt(
        "What is the weather like in my location?",
        arguments=KernelArguments(
            settings={
                service_id: PromptExecutionSettings(
                    service_id=service_id,
                    function_choice_behavior=FunctionChoiceBehavior.Auto(),
                ),
            }
        ),
    )
```
In the example above, the settings will be overridden to None.

### Description

<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->
1. Fix the bug.
2. Fix mypy in the pre-commit hook in order to commit.

### 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/.pre-commit-config.yaml

@@ -49,7 +49,7 @@ repos:
     - id: mypy
       files: ^python/semantic_kernel/
       name: mypy
-      entry: cd python && uv run mypy -p semantic_kernel --config-file mypy.ini
+      entry: uv run mypy -p semantic_kernel --config-file python/mypy.ini
       language: system
       types: [python]
       pass_filenames: false

python/semantic_kernel/functions/kernel_arguments.py

@@ -43,3 +43,9 @@ def __init__(
             else:
                 settings_dict = {settings.service_id or DEFAULT_SERVICE_NAME: settings}
         self.execution_settings: dict[str, "PromptExecutionSettings"] | None = settings_dict
+
+    def __bool__(self) -> bool:
+        """Returns True if the arguments have any values."""
+        has_arguments = self.__len__() > 0
+        has_execution_settings = self.execution_settings is not None and len(self.execution_settings) > 0
+        return has_arguments or has_execution_settings

python/semantic_kernel/kernel.py

@@ -41,9 +41,7 @@
 from semantic_kernel.utils.naming import generate_random_ascii_name
 
 if TYPE_CHECKING:
-    from semantic_kernel.connectors.ai.function_choice_behavior import (
-        FunctionChoiceBehavior,
-    )
+    from semantic_kernel.connectors.ai.function_choice_behavior import FunctionChoiceBehavior
     from semantic_kernel.connectors.ai.prompt_execution_settings import PromptExecutionSettings
     from semantic_kernel.functions.kernel_function import KernelFunction
 
@@ -239,7 +237,7 @@ async def invoke_prompt(
         Returns:
             FunctionResult | list[FunctionResult] | None: The result of the function(s)
         """
-        if not arguments:
+        if arguments is None:
             arguments = KernelArguments(**kwargs)
         if not prompt:
             raise TemplateSyntaxError("The prompt is either null or empty.")
@@ -280,7 +278,7 @@ async def invoke_prompt_stream(
         Returns:
             AsyncIterable[StreamingContentMixin]: The content of the stream of the last function provided.
         """
-        if not arguments:
+        if arguments is None:
             arguments = KernelArguments(**kwargs)
         if not prompt:
             raise TemplateSyntaxError("The prompt is either null or empty.")

python/tests/unit/functions/test_kernel_arguments.py

@@ -35,3 +35,14 @@ def test_kernel_arguments_with_execution_settings():
     kargs = KernelArguments(settings=[test_pes])
     assert kargs is not None
     assert kargs.execution_settings == {"test": test_pes}
+
+
+def test_kernel_arguments_bool():
+    # An empty KernelArguments object should return False
+    assert not KernelArguments()
+    # An KernelArguments object with keyword arguments should return True
+    assert KernelArguments(input=10)
+    # An KernelArguments object with execution_settings should return True
+    assert KernelArguments(settings=PromptExecutionSettings(service_id="test"))
+    # An KernelArguments object with both keyword arguments and execution_settings should return True
+    assert KernelArguments(input=10, settings=PromptExecutionSettings(service_id="test"))