Add context manager to enable python forwarding

python/lsst/log/log/logContinued.py

@@ -278,6 +278,19 @@ def isEnabledFor(self, level):
         return Log.getDefaultLogger().isEnabledFor(level)
 
 
+class UsePythonLogging:
+    """Context manager to enable Python log forwarding temporarily."""
+
+    def __init__(self):
+        self.current = Log.UsePythonLogging
+
+    def __enter__(self):
+        Log.usePythonLogging()
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        Log.UsePythonLogging = self.current
+
+
 class LogHandler(logging.Handler):
     """Handler for Python logging module that emits to LSST logging.
 

tests/test_log.py

@@ -602,6 +602,27 @@ def testLogLoop(self):
 
         logging.shutdown()
 
+    def testForwardToPythonContextManager(self):
+        """Test that `lsst.log` log messages can be forwarded to `logging`
+        using context manager"""
+        log.configure()
+
+        # Without forwarding we only get python logger messages captured
+        with self.assertLogs(level="WARNING") as cm:
+            log.warn("lsst.log: not forwarded")
+            logging.warning("Python logging: captured")
+        self.assertEqual(len(cm.output), 1)
+
+        # Temporarily turn on forwarding
+        with log.UsePythonLogging():
+            with self.assertLogs(level="WARNING") as cm:
+                log.warn("lsst.log: forwarded")
+                logging.warning("Python logging: also captured")
+            self.assertEqual(len(cm.output), 2)
+
+        # Verify that forwarding is disabled
+        self.assertFalse(log.Log.UsePythonLogging)
+
 
 if __name__ == "__main__":
     unittest.main()