Update update_transformers validation

rdt/errors.py

@@ -7,3 +7,7 @@ class NotFittedError(Exception):
 
 class Error(Exception):
     """Error to raise when ``HyperTransformer`` produces a controlled error message."""
+
+
+class InvalidSdtypeForTransformerError(Exception):
+    """Error to raise when the sdtype is not supported by the transformer."""

rdt/hyper_transformer.py

@@ -9,7 +9,7 @@
 import pandas as pd
 import yaml
 
-from rdt.errors import Error, NotFittedError
+from rdt.errors import Error, InvalidSdtypeForTransformerError, NotFittedError
 from rdt.transformers import (
     BaseTransformer, get_class_by_transformer_name, get_default_transformer,
     get_transformer_instance, get_transformers_by_type)
@@ -442,21 +442,17 @@ def update_transformers(self, column_name_to_transformer):
         self._validate_update_columns(update_columns)
         self._validate_transformers(column_name_to_transformer)
 
-        incompatible_sdtypes = []
         for column_name, transformer in column_name_to_transformer.items():
             if transformer is not None:
                 current_sdtype = self.field_sdtypes.get(column_name)
                 if current_sdtype and current_sdtype not in transformer.get_supported_sdtypes():
-                    incompatible_sdtypes.append(column_name)
+                    raise InvalidSdtypeForTransformerError(
+                        f"Column '{column_name}' is a {current_sdtype} column, which is "
+                        f"incompatible with the '{type(transformer).__name__}' transformer."
+                    )
 
             self.field_transformers[column_name] = transformer
 
-        if incompatible_sdtypes:
-            warnings.warn(
-                "Some transformers you've assigned are not compatible with the sdtypes. "
-                f"Use 'update_sdtypes' to update: {incompatible_sdtypes}"
-            )
-
         self._modified_config = True
 
     def remove_transformers(self, column_names):

tests/integration/test_transformers.py

@@ -5,6 +5,7 @@
 import pytest
 
 from rdt import HyperTransformer
+from rdt.errors import InvalidSdtypeForTransformerError
 from rdt.performance.datasets import BaseDatasetGenerator
 from rdt.transformers import BaseTransformer
 
@@ -255,7 +256,11 @@ def _test_transformer_with_hypertransformer(transformer_class, input_data, steps
         }
 
     hypertransformer.detect_initial_config(input_data)
-    hypertransformer.update_transformers(field_transformers)
+    try:
+        hypertransformer.update_transformers(field_transformers)
+    except InvalidSdtypeForTransformerError:
+        pass
+
     hypertransformer.fit(input_data)
 
     transformed = hypertransformer.transform(input_data)

tests/unit/test_hyper_transformer.py

@@ -10,7 +10,7 @@
 import pytest
 
 from rdt import HyperTransformer
-from rdt.errors import Error, NotFittedError
+from rdt.errors import Error, InvalidSdtypeForTransformerError, NotFittedError
 from rdt.transformers import (
     AnonymizedFaker, BinaryEncoder, FloatFormatter, FrequencyEncoder, GaussianNormalizer,
     LabelEncoder, OneHotEncoder, RegexGenerator, UnixTimestampEncoder)
@@ -2484,16 +2484,15 @@ def test_update_transformers_missmatch_sdtypes(self, mock_warnings):
             'my_column': transformer
         }
 
-        # Run
-        instance.update_transformers(column_name_to_transformer)
-
-        # Assert
-        expected_call = (
-            "Some transformers you've assigned are not compatible with the sdtypes. "
-            f"Use 'update_sdtypes' to update: {'my_column'}"
+        # Run and Assert
+        err_msg = re.escape(
+            "Column 'my_column' is a categorical column, which is incompatible "
+            "with the 'BinaryEncoder' transformer."
         )
+        with pytest.raises(InvalidSdtypeForTransformerError, match=err_msg):
+            instance.update_transformers(column_name_to_transformer)
 
-        assert mock_warnings.called_once_with(expected_call)
+        assert mock_warnings.called_once_with(err_msg)
         instance._validate_transformers.assert_called_once_with(column_name_to_transformer)
 
     def test_update_transformers_transformer_is_none(self):