Add --log-disable CLI option (#10371)

Fixes #7431

changelog/7431.feature.rst

@@ -0,0 +1 @@
+``--log-disable`` CLI option added to disable individual loggers.

doc/en/how-to/logging.rst

@@ -55,6 +55,13 @@ These options can also be customized through ``pytest.ini`` file:
     log_format = %(asctime)s %(levelname)s %(message)s
     log_date_format = %Y-%m-%d %H:%M:%S
 
+Specific loggers can be disabled via ``--log-disable={logger_name}``.
+This argument can be passed multiple times:
+
+.. code-block:: bash
+
+    pytest --log-disable=main --log-disable=testing
+
 Further it is possible to disable reporting of captured content (stdout,
 stderr and logs) on failed tests completely with:
 

src/_pytest/logging.py

@@ -297,6 +297,13 @@ def pytest_addoption(parser: Parser) -> None:
         default=None,
         help="Auto-indent multiline messages passed to the logging module. Accepts true|on, false|off or an integer.",
     )
+    group.addoption(
+        "--log-disable",
+        action="append",
+        default=[],
+        dest="logger_disable",
+        help="Disable a logger by name. Can be passed multipe times.",
+    )
 
 
 _HandlerType = TypeVar("_HandlerType", bound=logging.Handler)
@@ -594,6 +601,15 @@ class LoggingPlugin:
             get_option_ini(config, "log_auto_indent"),
         )
         self.log_cli_handler.setFormatter(log_cli_formatter)
+        self._disable_loggers(loggers_to_disable=config.option.logger_disable)
+
+    def _disable_loggers(self, loggers_to_disable: List[str]) -> None:
+        if not loggers_to_disable:
+            return
+
+        for name in loggers_to_disable:
+            logger = logging.getLogger(name)
+            logger.disabled = True
 
     def _create_formatter(self, log_format, log_date_format, auto_indent):
         # Color option doesn't exist if terminal plugin is disabled.

testing/logging/test_reporting.py

@@ -1165,3 +1165,72 @@ def test_log_file_cli_subdirectories_are_successfully_created(
     result = pytester.runpytest("--log-file=foo/bar/logf.log")
     assert "logf.log" in os.listdir(expected)
     assert result.ret == ExitCode.OK
+
+
+def test_disable_loggers(testdir):
+    testdir.makepyfile(
+        """
+        import logging
+        import os
+        disabled_log = logging.getLogger('disabled')
+        test_log = logging.getLogger('test')
+        def test_logger_propagation(caplog):
+            with caplog.at_level(logging.DEBUG):
+                disabled_log.warning("no log; no stderr")
+                test_log.debug("Visible text!")
+                assert caplog.record_tuples == [('test', 10, 'Visible text!')]
+         """
+    )
+    result = testdir.runpytest("--log-disable=disabled", "-s")
+    assert result.ret == ExitCode.OK
+    assert not result.stderr.lines
+
+
+def test_disable_loggers_does_not_propagate(testdir):
+    testdir.makepyfile(
+        """
+    import logging
+    import os
+
+    parent_logger = logging.getLogger("parent")
+    child_logger = parent_logger.getChild("child")
+
+    def test_logger_propagation_to_parent(caplog):
+            with caplog.at_level(logging.DEBUG):
+                parent_logger.warning("some parent logger message")
+                child_logger.warning("some child logger message")
+                assert len(caplog.record_tuples) == 1
+                assert caplog.record_tuples[0][0] == "parent"
+                assert caplog.record_tuples[0][2] == "some parent logger message"
+    """
+    )
+
+    result = testdir.runpytest("--log-disable=parent.child", "-s")
+    assert result.ret == ExitCode.OK
+    assert not result.stderr.lines
+
+
+def test_log_disabling_works_with_log_cli(testdir):
+    testdir.makepyfile(
+        """
+    import logging
+    disabled_log = logging.getLogger('disabled')
+    test_log = logging.getLogger('test')
+
+    def test_log_cli_works(caplog):
+        test_log.info("Visible text!")
+        disabled_log.warning("This string will be suppressed.")
+    """
+    )
+    result = testdir.runpytest(
+        "--log-cli-level=DEBUG",
+        "--log-disable=disabled",
+    )
+    assert result.ret == ExitCode.OK
+    result.stdout.fnmatch_lines(
+        "INFO     test:test_log_disabling_works_with_log_cli.py:6 Visible text!"
+    )
+    result.stdout.no_fnmatch_line(
+        "WARNING  disabled:test_log_disabling_works_with_log_cli.py:7 This string will be suppressed."
+    )
+    assert not result.stderr.lines