Added type checking to rich_text_to_string().

Author: kmvanbrunt

cmd2/rich_utils.py

@@ -426,7 +426,13 @@ def rich_text_to_string(text: Text) -> str:
 
     :param text: the text object to convert
     :return: the resulting string with ANSI styles preserved.
+    :raises TypeError: if text is not a rich.text.Text object
     """
+    # Strictly enforce Text type. While console.print() can render any object,
+    # this function is specifically tailored to convert Text instances to strings.
+    if not isinstance(text, Text):
+        raise TypeError(f"rich_text_to_string() expected a rich.text.Text object, but got {type(text).__name__}")
+
     console = Console(
         force_terminal=True,
         soft_wrap=True,

tests/test_rich_utils.py

@@ -81,6 +81,12 @@ def test_rich_text_to_string(rich_text: Text, string: str) -> None:
     assert ru.rich_text_to_string(rich_text) == string
 
 
+def test_rich_text_to_string_type_error() -> None:
+    with pytest.raises(TypeError) as excinfo:
+        ru.rich_text_to_string("not a Text object")  # type: ignore[arg-type]
+    assert "rich_text_to_string() expected a rich.text.Text object, but got str" in str(excinfo.value)
+
+
 def test_set_theme() -> None:
     # Save a cmd2, rich-argparse, and rich-specific style.
     cmd2_style_key = Cmd2Style.ERROR