Closes #26559: Allow configuring flush-on-close behaviour of MemoryHandler.

1 files changed, 31 insertions, 1 deletions

diff --git a/Lib/test/test_logging.py b/Lib/test/test_logging.py
index 062df0f746..9e9a439eab 100644
--- a/Lib/test/test_logging.py
+++ b/Lib/test/test_logging.py
@@ -958,7 +958,7 @@ class MemoryHandlerTest(BaseTest):
     def setUp(self):
         BaseTest.setUp(self)
         self.mem_hdlr = logging.handlers.MemoryHandler(10, logging.WARNING,
-                                                        self.root_hdlr)
+                                                       self.root_hdlr)
         self.mem_logger = logging.getLogger('mem')
         self.mem_logger.propagate = 0
         self.mem_logger.addHandler(self.mem_hdlr)
@@ -995,6 +995,36 @@ class MemoryHandlerTest(BaseTest):
         self.mem_logger.debug(self.next_message())
         self.assert_log_lines(lines)
 
+    def test_flush_on_close(self):
+        """
+        Test that the flush-on-close configuration works as expected.
+        """
+        self.mem_logger.debug(self.next_message())
+        self.assert_log_lines([])
+        self.mem_logger.info(self.next_message())
+        self.assert_log_lines([])
+        self.mem_logger.removeHandler(self.mem_hdlr)
+        # Default behaviour is to flush on close. Check that it happens.
+        self.mem_hdlr.close()
+        lines = [
+            ('DEBUG', '1'),
+            ('INFO', '2'),
+        ]
+        self.assert_log_lines(lines)
+        # Now configure for flushing not to be done on close.
+        self.mem_hdlr = logging.handlers.MemoryHandler(10, logging.WARNING,
+                                                       self.root_hdlr,
+                                                       False)
+        self.mem_logger.addHandler(self.mem_hdlr)
+        self.mem_logger.debug(self.next_message())
+        self.assert_log_lines(lines)  # no change
+        self.mem_logger.info(self.next_message())
+        self.assert_log_lines(lines)  # no change
+        self.mem_logger.removeHandler(self.mem_hdlr)
+        self.mem_hdlr.close()
+        # assert that no new lines have been added
+        self.assert_log_lines(lines)  # no change
+
 
 class ExceptionFormatter(logging.Formatter):
     """A special exception formatter."""