Fix nested caplog.filtering() removing filter early

changelog/14189.bugfix.rst

@@ -0,0 +1 @@
+Fixed nested :meth:`caplog.filtering() <pytest.LogCaptureFixture.filtering>` calls with the same filter removing the filter too early when the inner context exits.

src/_pytest/logging.py

@@ -581,15 +581,22 @@ def filtering(self, filter_: logging.Filter) -> Generator[None]:
         :meth:`handler` for the 'with' statement block, and removes that filter at the
         end of the block.
 
+        If the filter is already attached to the handler (e.g. from an outer
+        nested ``filtering()`` call), it is not added again, and will not be
+        removed when the inner block exits.
+
         :param filter_: A custom :class:`logging.Filter` object.
 
         .. versionadded:: 7.5
         """
-        self.handler.addFilter(filter_)
+        already_present = filter_ in self.handler.filters
+        if not already_present:
+            self.handler.addFilter(filter_)
         try:
             yield
         finally:
-            self.handler.removeFilter(filter_)
+            if not already_present:
+                self.handler.removeFilter(filter_)
 
 
 @fixture

testing/logging/test_fixture.py

@@ -206,6 +206,27 @@ def filter(self, record: logging.LogRecord) -> bool:
     assert unfiltered_tuple == ("test_fixture", 20, "handler call")
 
 
+def test_nested_filtering_same_filter(caplog: pytest.LogCaptureFixture) -> None:
+    """Nested ``caplog.filtering()`` with the same filter should not remove
+    the filter when the inner context exits (#14189)."""
+
+    class NoCaptureFilter(logging.Filter):
+        def filter(self, record: logging.LogRecord) -> bool:
+            return False
+
+    filter_instance = NoCaptureFilter()
+    with caplog.at_level(logging.INFO):
+        with caplog.filtering(filter_instance):
+            logger.info("outer before inner")
+            with caplog.filtering(filter_instance):
+                logger.info("inside inner")
+            logger.info("outer after inner")
+        logger.info("outside both")
+
+    assert len(caplog.records) == 1
+    assert caplog.records[0].message == "outside both"
+
+
 @pytest.mark.parametrize(
     "level_str,expected_disable_level",
     [