FIX parametrizing estimator checks allows custom estimators that implements __call__ (scikit-learn#28860)

randolf-scholz · adrinjalali · jeremiedbb · web-flow · commit 1210b0685b4b · 2024-04-22T09:07:34.000Z
Co-authored-by: Adrin Jalali &lt;adrin.jalali@gmail.com&gt;
Co-authored-by: jeremiedbb &lt;jeremiedbb@yahoo.fr&gt;
diff --git a/sklearn/tests/test_common.py b/sklearn/tests/test_common.py
@@ -20,6 +20,7 @@
 import pytest
 
 import sklearn
+from sklearn.base import BaseEstimator
 from sklearn.cluster import (
     OPTICS,
     AffinityPropagation,
@@ -103,6 +104,16 @@ def _sample_func(x, y=1):
     pass
 
 
+class CallableEstimator(BaseEstimator):
+    """Dummy development stub for an estimator.
+
+    This is to make sure a callable estimator passes common tests.
+    """
+
+    def __call__(self):
+        pass  # pragma: nocover
+
+
 @pytest.mark.parametrize(
     "val, expected",
     [
@@ -122,6 +133,7 @@ def _sample_func(x, y=1):
                 "solver='newton-cg',warm_start=True)"
             ),
         ),
+        (CallableEstimator(), "CallableEstimator()"),
     ],
 )
 def test_get_check_estimator_ids(val, expected):
diff --git a/sklearn/utils/estimator_checks.py b/sklearn/utils/estimator_checks.py
@@ -9,7 +9,7 @@
 from contextlib import nullcontext
 from copy import deepcopy
 from functools import partial, wraps
-from inspect import signature
+from inspect import isfunction, signature
 from numbers import Integral, Real
 
 import joblib
@@ -405,13 +405,11 @@ def _get_check_estimator_ids(obj):
     --------
     check_estimator
     """
-    if callable(obj):
-        if not isinstance(obj, partial):
-            return obj.__name__
-
+    if isfunction(obj):
+        return obj.__name__
+    if isinstance(obj, partial):
         if not obj.keywords:
             return obj.func.__name__
-
         kwstring = ",".join(["{}={}".format(k, v) for k, v in obj.keywords.items()])
         return "{}({})".format(obj.func.__name__, kwstring)
     if hasattr(obj, "get_params"):
