fix: replace TextIOWrapper with StringIO in CaptureStream to avoid uninitialized object error

CaptureStream inherited from TextIOWrapper without calling super().__init__(),
leaving the internal C struct (self->ok) at 0. When mypy (or other tools)
interacted with the stream, Python's C-level CHECK_INITIALIZED raised
'I/O operation on uninitialized object'.

Changed to inherit from StringIO which is a pure Python stream that doesn't
require C-level initialization, and updated get_hidden_stdout/get_hidden_stderr
to use getvalue() instead of the custom .contents attribute.

Author: sbrunner

prospector/tools/utils.py

@@ -1,26 +1,19 @@
 import sys
-from io import TextIOWrapper
+from io import StringIO
 from typing import Optional
 
 
-class CaptureStream(TextIOWrapper):
+class CaptureStream(StringIO):
     def __init__(self, tty: bool) -> None:
-        self.contents = ""
+        super().__init__()
         self._tty = tty
 
-    def write(self, text: str, /) -> int:
-        self.contents += text
-        return len(text)
+    def isatty(self) -> bool:
+        return self._tty
 
     def close(self) -> None:
         pass
 
-    def flush(self) -> None:
-        pass
-
-    def isatty(self) -> bool:
-        return self._tty
-
 
 class CaptureOutput:
     _prev_streams = None
@@ -47,10 +40,10 @@ def __enter__(self) -> "CaptureOutput":
         return self
 
     def get_hidden_stdout(self) -> str:
-        return "" if self.stdout is None else self.stdout.contents
+        return "" if self.stdout is None else self.stdout.getvalue()
 
     def get_hidden_stderr(self) -> str:
-        return "" if self.stderr is None else self.stderr.contents
+        return "" if self.stderr is None else self.stderr.getvalue()
 
     def __exit__(self, exc_type: type, exc_val: Exception, exc_tb: type) -> None:
         if self.hide: