Preserve falsey supplied loggers and output files

src/h2/config.py

@@ -66,7 +66,7 @@ class OutputLogger:
 
     def __init__(self, file=None, trace_level=False) -> None:  # type: ignore
         super().__init__()
-        self.file = file or sys.stderr
+        self.file = sys.stderr if file is None else file
         self.trace_level = trace_level
 
     def debug(self, fmtstr, *args) -> None:  # type: ignore
@@ -184,7 +184,7 @@ def __init__(self,
         self.split_outbound_cookies = split_outbound_cookies
         self.validate_inbound_headers = validate_inbound_headers
         self.normalize_inbound_headers = normalize_inbound_headers
-        self.logger = logger or DummyLogger(__name__)
+        self.logger = DummyLogger(__name__) if logger is None else logger
 
     @property
     def header_encoding(self) -> bool | str | None:

tests/test_config.py

@@ -3,6 +3,7 @@
 """
 from __future__ import annotations
 
+import io
 import logging
 
 import pytest
@@ -129,6 +130,46 @@ def test_logger_instance_is_reflected(self) -> None:
         config.logger = logger
         assert config.logger is logger
 
+    def test_falsey_logger_is_used(self) -> None:
+        messages: list[str] = []
+
+        class EmptyLogger(h2.config.DummyLogger):
+            def __len__(self) -> int:
+                return len(messages)
+
+            def debug(self, *args: object, **kwargs: object) -> None:
+                messages.append("debug")
+
+            def trace(self, *args: object, **kwargs: object) -> None:
+                messages.append("trace")
+
+        logger = EmptyLogger()
+        assert not logger
+        config = h2.config.H2Configuration(logger=logger)
+
+        assert config.logger is logger
+        config.logger.debug("owned debug")
+        config.logger.trace("owned trace")
+        assert messages == ["debug", "trace"]
+
+    @pytest.mark.parametrize("trace_level", [False, True])
+    def test_falsey_file_is_used(self, capsys, trace_level) -> None:
+        class FalseyFile(io.StringIO):
+            def __bool__(self) -> bool:
+                return False
+
+        with FalseyFile() as output:
+            logger = h2.config.OutputLogger(file=output, trace_level=trace_level)
+            logger.debug("owned debug")
+            logger.trace("owned trace")
+
+            expected = "h2 (debug): owned debug\n"
+            if trace_level:
+                expected += "h2 (trace): owned trace\n"
+            assert output.getvalue() == expected
+            assert not output.closed
+            assert capsys.readouterr().err == ""
+
     @pytest.mark.parametrize("trace_level", [False, True])
     def test_output_logger(self, capsys, trace_level) -> None:
         logger = h2.config.OutputLogger(trace_level=trace_level)