fix

imblearn/over_sampling/_smote/tests/test_smoten.py

@@ -66,7 +66,7 @@ def test_smoten_sparse_input(data, sparse_format):
     https://github.com/scikit-learn-contrib/imbalanced-learn/issues/971
     """
     X, y = data
-    X = OneHotEncoder(sparse_output=False).fit_transform(X)
+    X = OneHotEncoder().fit_transform(X).toarray()
     X = _convert_container(X, sparse_format)
 
     with pytest.warns(DataConversionWarning, match="is not really efficient"):

imblearn/utils/tests/test_param_validation.py

@@ -11,6 +11,7 @@
 from sklearn.utils import deprecated
 
 from imblearn._config import config_context, get_config
+from imblearn.base import _ParamsValidationMixin
 from imblearn.utils._param_validation import (
     HasMethods,
     Hidden,
@@ -62,7 +63,7 @@ def _deprecated_method(self, a):
         """A deprecated validated method"""
 
 
-class _Estimator(BaseEstimator):
+class _Estimator(_ParamsValidationMixin, BaseEstimator):
     """An estimator to test the validation of estimator parameters."""
 
     _parameter_constraints: dict = {"a": [Real]}