native loggers: add is_enabled_for & get_effective_level

CHANGELOG.md

@@ -22,6 +22,9 @@ You can find our backwards-compatibility policy [here](https://github.com/hynek/
   With it, you do not need to add `structlog.stdlib.PositionalArgumentsFormatter` processor to format positional arguments from *structlog* loggers.
   [#668](https://github.com/hynek/structlog/pull/668)
 
+- Native loggers now have `is_enabled_for()` and `get_effective_level()` methods that mirror the behavior of the standard library's `logging.Logger.isEnabledFor()` and `logging.Logger.getEffectiveLevel()`.
+  [#689](https://github.com/hynek/structlog/pull/689)
+
 
 ## Changed
 

src/structlog/_native.py

@@ -219,6 +219,10 @@ async def alog(
     meths["msg"] = meths["info"]
     meths["amsg"] = meths["ainfo"]
 
+    # Introspection
+    meths["is_enabled_for"] = lambda self, level: level >= min_level
+    meths["get_effective_level"] = lambda self: min_level
+
     return type(
         f"BoundLoggerFilteringAt{LEVEL_TO_NAME.get(min_level, 'Notset').capitalize()}",
         (BoundLoggerBase,),

src/structlog/typing.py

@@ -190,6 +190,20 @@ def new(self, **new_values: Any) -> FilteringBoundLogger:
         .. versionadded:: 22.1.0
         """
 
+    def is_enabled_for(self, level: int) -> bool:
+        """
+        Check whether the logger is enabled for *level*.
+
+        .. versionadded:: 25.1.0
+        """
+
+    def get_effective_level(self) -> int:
+        """
+        Return the effective level of the logger.
+
+        .. versionadded:: 25.1.0
+        """
+
     def debug(self, event: str, *args: Any, **kw: Any) -> Any:
         """
         Log ``event % args`` with **kw** at **debug** level.

tests/test_log_levels.py → tests/test_native.py

@@ -23,7 +23,23 @@ def _bl(cl):
     return make_filtering_bound_logger(logging.INFO)(cl, [], {})
 
 
-class TestFilteringLogger:
+class TestNativeFilteringLogger:
+    def test_is_enabled_for(self, bl):
+        """
+        is_enabled_for returns True if the log level is enabled.
+        """
+        assert bl.is_enabled_for(20)
+        assert bl.is_enabled_for(logging.INFO)
+
+        assert not bl.is_enabled_for(19)
+        assert not bl.is_enabled_for(logging.DEBUG)
+
+    def test_get_effective_level(self, bl):
+        """
+        get_effective_level returns the log level.
+        """
+        assert 20 == logging.INFO == bl.get_effective_level()
+
     def test_exact_level(self, bl, cl):
         """
         if log level is exactly the min_level, log.

tests/typing/api.py

@@ -44,17 +44,10 @@ def bytes_dumps(
     processors=[structlog.processors.JSONRenderer(serializer=bytes_dumps)]
 )
 
-structlog.configure(
-    processors=[
-        structlog.stdlib.render_to_log_args_and_kwargs,
-    ],
-    logger_factory=structlog.stdlib.LoggerFactory(),
-    wrapper_class=structlog.stdlib.BoundLogger,
-    cache_logger_on_first_use=True,
-)
 
 structlog.configure(
     processors=[
+        structlog.stdlib.render_to_log_args_and_kwargs,
         structlog.stdlib.filter_by_level,
         structlog.stdlib.add_logger_name,
         structlog.stdlib.add_log_level,
@@ -359,3 +352,9 @@ def typecheck_bound_logger_return() -> None:
 
 fbl: FilteringBoundLogger = structlog.get_logger()
 fbl.info("Hello %s! The answer is %d.", "World", 42, x=1)
+
+
+# Introspection
+level: int = fbl.get_effective_level()
+is_active: bool = fbl.is_enabled_for(logging.INFO)
+is_active = fbl.is_enabled_for(20)