scikit-learn · glemaitre · Oct 22, 2021 · Oct 18, 2021 · Oct 19, 2021 · Oct 19, 2021
diff --git a/sklearn/tests/test_common.py b/sklearn/tests/test_common.py
@@ -16,6 +16,7 @@
 from functools import partial
 
 import pytest
+import numpy as np
 
 from sklearn.utils import all_estimators
 from sklearn.utils._testing import ignore_warnings
@@ -403,3 +404,47 @@ def test_transformers_get_feature_names_out(transformer):
         check_transformer_get_feature_names_out_pandas(
             transformer.__class__.__name__, transformer
         )
+
+
+VALIDATE_ESTIMATOR_INIT = [
+    "ColumnTransformer",
+    "FactorAnalysis",
+    "FastICA",
+    "FeatureHasher",
+    "FeatureUnion",
+    "GridSearchCV",
+    "HalvingGridSearchCV",
+    "KernelDensity",
+    "KernelPCA",
+    "LabelBinarizer",
+    "NuSVC",
+    "NuSVR",
+    "OneClassSVM",
+    "Pipeline",
+    "RadiusNeighborsClassifier",
+    "SGDOneClassSVM",
+    "SVC",
+    "SVR",
+    "TheilSenRegressor",
+    "TweedieRegressor",
+]
+VALIDATE_ESTIMATOR_INIT = set(VALIDATE_ESTIMATOR_INIT)
+
+
+@pytest.mark.parametrize(
+    "Estimator",
+    [est for name, est in all_estimators() if name not in VALIDATE_ESTIMATOR_INIT],
+)
+def test_estimators_do_not_raise_errors_in_init_or_set_params(Estimator):
+    """Check that init or set_param does not raise errors."""
+    params = signature(Estimator).parameters
+
+    smoke_test_values = [-1, 3.0, "helloworld", np.array([1.0, 4.0]), {}, []]
+    for value in smoke_test_values:
+        new_params = {key: value for key in params}
+
+        # Does not raise
+        est = Estimator(**new_params)
+
+        # Also do does not raise
+        est.set_params(**new_params)
diff --git a/sklearn/utils/metaestimators.py b/sklearn/utils/metaestimators.py
@@ -29,8 +29,18 @@ def _get_params(self, attr, deep=True):
         out = super().get_params(deep=deep)
         if not deep:
             return out
+
         estimators = getattr(self, attr)
-        out.update(estimators)
+        try:
+            out.update(estimators)
+        except (TypeError, ValueError):
+            # Ignore TypeError for cases where estimators is not a list of
+            # (name, estimator) and ignore ValueError when the list is not
+            # formated correctly. This is to prevent errors when calling
+            # `set_params`. `BaseEstimator.set_params` calls `get_params` which
+            # can error for invalid values for `estimators`.
+            return out
+
         for name, estimator in estimators:
             if hasattr(estimator, "get_params"):
                 for key, value in estimator.get_params(deep=True).items():
@@ -42,14 +52,15 @@ def _set_params(self, attr, **params):
         # 1. All steps
         if attr in params:
             setattr(self, attr, params.pop(attr))
-        # 2. Step replacement
+        # 2. Replace items with estimators in params
         items = getattr(self, attr)
-        names = []
-        if items:
-            names, _ = zip(*items)
-        for name in list(params.keys()):
-            if "__" not in name and name in names:
-                self._replace_estimator(attr, name, params.pop(name))
+        if isinstance(items, list) and items:
+            # Get item names used to identify valid names in params
+            item_names, _ = zip(*items)
+            for name in list(params.keys()):
+                if "__" not in name and name in item_names:
+                    self._replace_estimator(attr, name, params.pop(name))
+
         # 3. Step parameters and other initialisation arguments
         super().set_params(**params)
         return self