MAINT Use check_scalar in _BaseStacking (#22405)

genvalen · glemaitre · ogrisel · web-flow · commit 65ae1a8586fc · 2022-04-17T08:30:21.000-04:00
Co-authored-by: Guillaume Lemaitre &lt;g.lemaitre58@gmail.com&gt;
Co-authored-by: Olivier Grisel &lt;olivier.grisel@ensta.org&gt;
diff --git a/sklearn/ensemble/_stacking.py b/sklearn/ensemble/_stacking.py
@@ -31,6 +31,7 @@
 from ..utils.metaestimators import available_if
 from ..utils.multiclass import check_classification_targets
 from ..utils.validation import check_is_fitted
+from ..utils.validation import check_scalar
 from ..utils.validation import column_or_1d
 from ..utils.fixes import delayed
 from ..utils.validation import _check_feature_names_in
@@ -161,6 +162,13 @@ def fit(self, X, y, sample_weight=None):
         -------
         self : object
         """
+        # Check params.
+        check_scalar(
+            self.passthrough,
+            name="passthrough",
+            target_type=(np.bool_, bool),
+            include_boundaries="neither",
+        )
         # all_estimators contains all estimators, the one to be fitted and the
         # 'drop' string.
         names, all_estimators = self._validate_estimators()
diff --git a/sklearn/ensemble/tests/test_stacking.py b/sklearn/ensemble/tests/test_stacking.py
@@ -317,6 +317,12 @@ def fit(self, X, y):
             TypeError,
             "does not support sample weight",
         ),
+        (
+            y_iris,
+            {"estimators": [("lr", LogisticRegression())], "passthrough": "foo"},
+            TypeError,
+            "passthrough must be an instance of",
+        ),
     ],
 )
 def test_stacking_classifier_error(y, params, type_err, msg_err):
@@ -350,6 +356,12 @@ def test_stacking_classifier_error(y, params, type_err, msg_err):
             TypeError,
             "does not support sample weight",
         ),
+        (
+            y_diabetes,
+            {"estimators": [("lr", LinearRegression())], "passthrough": "foo"},
+            TypeError,
+            "passthrough must be an instance of",
+        ),
     ],
 )
 def test_stacking_regressor_error(y, params, type_err, msg_err):
