improve StreamToCall class compatibility

boilerplates/logging.py

@@ -218,12 +218,24 @@ def unittest_verbosity() -> t.Optional[int]:
     return None
 
 
-class StreamToCall:
+class StreamToCall(t.IO[str]):
     """Redirect stream writes to a function call.
 
     Enable using logging instances as a file-like objects.
     Given a called_function, convert write(text) calls to called_function(text) calls.
     For example: StreamToCall(logging.warning) will redirect all writes to logging.warning().
+
+    Example usage:
+
+    logger = logging.getLogger(__name__)
+    with contextlib.redirect_stdout(boilerplates.logging.StreamToCall(logger.info)):
+        print('this will be logged at INFO level')
+
+    Another example:
+
+    logger = logging.getLogger(__name__)
+    stream = boilerplates.logging.StreamToCall(logger.debug)
+    print('this will be logged at DEBUG level', file=stream)
     """
 
     def __init__(self, called_function: collections.abc.Callable):
@@ -235,6 +247,7 @@ def write(self, message: str, *args):
         while message.endswith('\r') or message.endswith('\n'):
             message = message[:-1]
         self._function(message, *args)
+        return len(message)
 
     def flush(self):
         """Flush can be a no-op."""

test/test_logging.py

@@ -1,5 +1,6 @@
 """Unit tests for logging boilerplate."""
 
+import contextlib
 import inspect
 import logging
 import os
@@ -103,7 +104,13 @@ def test_unittest_verbosity_not_unittest(self):
             verbosity = boilerplates.logging.unittest_verbosity()
         self.assertIsNone(verbosity)
 
-    def test_stream_to_call(self):
+    def test_stream_to_call_contextlib(self):
+        log = logging.getLogger(f'{__name__}.test_stream_to_call')
+        with contextlib.redirect_stdout(boilerplates.logging.StreamToCall(log.info)):
+            with self.assertLogs(logger=log, level='INFO'):
+                print('test output')
+
+    def test_stream_to_call_direct(self):
         log = logging.getLogger(f'{__name__}.test_stream_to_call')
         stream = boilerplates.logging.StreamToCall(log.info)
         with self.assertLogs(logger=log, level='INFO'):