DummyLogger can be called with unknown methods

CHANGELOG.md

@@ -74,6 +74,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 -
 
 
+
+- Added support for calling unknown methods with `DummyLogger` ([#13224](https://github.com/PyTorchLightning/pytorch-lightning/pull/13224))
+
 ### Changed
 
 - Enable validation during overfitting ([#12527](https://github.com/PyTorchLightning/pytorch-lightning/pull/12527))

src/pytorch_lightning/loggers/logger.py

@@ -346,6 +346,14 @@ def __iter__(self):
         # if DummyLogger is substituting a logger collection, pretend it is empty
         yield from ()
 
+    def __getattr__(self, name: str) -> Callable:
+        """Allows the DummyLogger to be called with arbitrary methods, to avoid AttributeErrors."""
+
+        def method(*args, **kwargs):
+            return None
+
+        return method
+
 
 def merge_dicts(
     dicts: Sequence[Mapping],

src/pytorch_lightning/trainer/trainer.py

@@ -589,7 +589,10 @@ def _init_debugging_flags(
             self.check_val_every_n_epoch = 1
             self.loggers = [DummyLogger()] if self.loggers else []
 
-            rank_zero_info(f"Running in fast_dev_run mode: will run the requested loop using {num_batches} batch(es).")
+            rank_zero_info(
+                f"Running in `fast_dev_run` mode: will run the requested loop using {num_batches} batch(es). "
+                "Logging and checkpointing is suppressed."
+            )
 
         self.limit_train_batches = _determine_batch_limits(limit_train_batches, "limit_train_batches")
         self.limit_val_batches = _determine_batch_limits(limit_val_batches, "limit_val_batches")

tests/tests_pytorch/loggers/test_logger.py

@@ -257,6 +257,14 @@ def test_dummylogger_noop_method_calls():
     logger.log_metrics("1", 2, three="three")
 
 
+def test_dummlogger_arbitrary_method_calls():
+    """Test that the DummyLogger can be called with non existing methods."""
+    logger = DummyLogger()
+    # Example method from WandbLogger
+    assert hasattr(logger, "log_text")
+    assert callable(logger.log_text)
+
+
 def test_dummyexperiment_support_item_assignment():
     """Test that the DummyExperiment supports item assignment."""
     experiment = DummyExperiment()