Add new filtering() method to LogCaptureFixture class (#11625)

Fixes #11610

AUTHORS

@@ -188,6 +188,7 @@ Javier Romero
 Jeff Rackauckas
 Jeff Widman
 Jenni Rinker
+Jens Tröger
 John Eddie Ayson
 John Litborn
 John Towler

changelog/11610.feature.rst

@@ -0,0 +1,2 @@
+Added :func:`LogCaptureFixture.filtering() <pytest.LogCaptureFixture.filtering>` context manager that
+adds a given :class:`logging.Filter` object to the caplog fixture.

src/_pytest/logging.py

@@ -564,6 +564,22 @@ class LogCaptureFixture:
             self.handler.setLevel(handler_orig_level)
             logging.disable(original_disable_level)
 
+    @contextmanager
+    def filtering(self, filter_: logging.Filter) -> Generator[None, None, None]:
+        """Context manager that temporarily adds the given filter to the caplog's
+        :meth:`handler` for the 'with' statement block, and removes that filter at the
+        end of the block.
+
+        :param filter_: A custom :class:`logging.Filter` object.
+
+        .. versionadded:: 7.5
+        """
+        self.handler.addFilter(filter_)
+        try:
+            yield
+        finally:
+            self.handler.removeFilter(filter_)
+
 
 @fixture
 def caplog(request: FixtureRequest) -> Generator[LogCaptureFixture, None, None]:

testing/logging/test_fixture.py

@@ -144,7 +144,7 @@ def test_change_level_undos_handler_level(pytester: Pytester) -> None:
     result.assert_outcomes(passed=3)
 
 
-def test_with_statement(caplog: pytest.LogCaptureFixture) -> None:
+def test_with_statement_at_level(caplog: pytest.LogCaptureFixture) -> None:
     with caplog.at_level(logging.INFO):
         logger.debug("handler DEBUG level")
         logger.info("handler INFO level")
@@ -159,7 +159,9 @@ def test_with_statement(caplog: pytest.LogCaptureFixture) -> None:
     assert "CRITICAL" in caplog.text
 
 
-def test_with_statement_logging_disabled(caplog: pytest.LogCaptureFixture) -> None:
+def test_with_statement_at_level_logging_disabled(
+    caplog: pytest.LogCaptureFixture,
+) -> None:
     logging.disable(logging.CRITICAL)
     assert logging.root.manager.disable == logging.CRITICAL
     with caplog.at_level(logging.WARNING):
@@ -185,6 +187,22 @@ def test_with_statement_logging_disabled(caplog: pytest.LogCaptureFixture) -> No
     assert logging.root.manager.disable == logging.CRITICAL
 
 
+def test_with_statement_filtering(caplog: pytest.LogCaptureFixture) -> None:
+    class TestFilter(logging.Filter):
+        def filter(self, record: logging.LogRecord) -> bool:
+            record.msg = "filtered handler call"
+            return True
+
+    with caplog.at_level(logging.INFO):
+        with caplog.filtering(TestFilter()):
+            logger.info("handler call")
+        logger.info("handler call")
+
+    filtered_tuple, unfiltered_tuple = caplog.record_tuples
+    assert filtered_tuple == ("test_fixture", 20, "filtered handler call")
+    assert unfiltered_tuple == ("test_fixture", 20, "handler call")
+
+
 @pytest.mark.parametrize(
     "level_str,expected_disable_level",
     [