Make core get_callbacks public for extensions (#504)

public get_callbacks for better extensions

nam/train/core.py

@@ -1235,7 +1235,7 @@ def _remove_checkpoint(self, trainer: pl.Trainer, filepath: str) -> None:
             nam_path.unlink()
 
 
-def _get_callbacks(
+def get_callbacks(
     threshold_esr: Optional[float],
     user_metadata: Optional[UserMetadata] = None,
     settings_metadata: Optional[metadata.Settings] = None,
@@ -1432,7 +1432,7 @@ def parse_user_latency(
     data_metadata = metadata.Data(latency=latency_analysis, checks=data_check_output)
 
     trainer = pl.Trainer(
-        callbacks=_get_callbacks(
+        callbacks=get_callbacks(
             threshold_esr,
             user_metadata=user_metadata,
             settings_metadata=settings_metadata,

tests/test_nam/test_train/test_core.py

@@ -295,5 +295,30 @@ def test_end_to_end():
         assert isinstance(train_output.model, Model)
 
 
+def test_get_callbacks():
+    """
+    Sanity check for get_callbacks with a custom extension callback and threshold_esr
+    """
+    threshold_esr = 0.01
+    callbacks = core.get_callbacks(threshold_esr=threshold_esr)
+
+    # dumb example of a user-extended custom callback
+    class CustomCallback:
+        pass
+    extended_callbacks = callbacks + [CustomCallback()]
+
+    # sanity default callbacks
+    assert any(isinstance(cb, core._ModelCheckpoint) for cb in extended_callbacks), \
+        "Expected _ModelCheckpoint to be part of the default callbacks."
+
+    # custom callback
+    assert any(isinstance(cb, CustomCallback) for cb in extended_callbacks), \
+        "Expected CustomCallback to be added to the extended callbacks."
+
+    # _ValidationStopping cb when threshold_esr is prvided
+    assert any(isinstance(cb, core._ValidationStopping) for cb in extended_callbacks), \
+        "_ValidationStopping should still be present after adding a custom callback."
+
+
 if __name__ == "__main__":
     pytest.main()