MAINT Fix scikit-learn#9350: Enable has_fit_parameter() and fit_score_takes_y() to work with @deprecated in Python 2 (scikit-learn#11277)

Author: markroth8

sklearn/utils/deprecation.py

@@ -78,6 +78,9 @@ def wrapped(*args, **kwargs):
             return fun(*args, **kwargs)
 
         wrapped.__doc__ = self._update_doc(wrapped.__doc__)
+        # Add a reference to the wrapped function so that we can introspect
+        # on function arguments in Python 2 (already works in Python 3)
+        wrapped.__wrapped__ = fun
 
         return wrapped
 

sklearn/utils/tests/test_estimator_checks.py

@@ -9,12 +9,14 @@
 from sklearn.externals import joblib
 
 from sklearn.base import BaseEstimator, ClassifierMixin
+from sklearn.utils import deprecated
 from sklearn.utils.testing import (assert_raises_regex, assert_true,
                                    assert_equal, ignore_warnings)
 from sklearn.utils.estimator_checks import check_estimator
 from sklearn.utils.estimator_checks import set_random_state
 from sklearn.utils.estimator_checks import set_checking_parameters
 from sklearn.utils.estimator_checks import check_estimators_unfitted
+from sklearn.utils.estimator_checks import check_fit_score_takes_y
 from sklearn.utils.estimator_checks import check_no_attributes_set_in_init
 from sklearn.ensemble import AdaBoostClassifier, RandomForestClassifier
 from sklearn.linear_model import LinearRegression, SGDClassifier
@@ -176,6 +178,19 @@ def transform(self, X):
         return sp.csr_matrix(X)
 
 
+def test_check_fit_score_takes_y_works_on_deprecated_fit():
+    # Tests that check_fit_score_takes_y works on a class with
+    # a deprecated fit method
+
+    class TestEstimatorWithDeprecatedFitMethod(BaseEstimator):
+        @deprecated("Deprecated for the purpose of testing "
+                    "check_fit_score_takes_y")
+        def fit(self, X, y):
+            return self
+
+    check_fit_score_takes_y("test", TestEstimatorWithDeprecatedFitMethod())
+
+
 def test_check_estimator():
     # tests that the estimator actually fails on "bad" estimators.
     # not a complete test of all checks, which are very extensive.

sklearn/utils/tests/test_validation.py

@@ -22,6 +22,7 @@
 from sklearn.utils.testing import assert_allclose_dense_sparse
 from sklearn.utils import as_float_array, check_array, check_symmetric
 from sklearn.utils import check_X_y
+from sklearn.utils import deprecated
 from sklearn.utils.mocking import MockDataFrame
 from sklearn.utils.estimator_checks import NotAnArray
 from sklearn.random_projection import sparse_random_matrix
@@ -563,6 +564,15 @@ def test_has_fit_parameter():
     assert_true(has_fit_parameter(SVR, "sample_weight"))
     assert_true(has_fit_parameter(SVR(), "sample_weight"))
 
+    class TestClassWithDeprecatedFitMethod:
+        @deprecated("Deprecated for the purpose of testing has_fit_parameter")
+        def fit(self, X, y, sample_weight=None):
+            pass
+
+    assert has_fit_parameter(TestClassWithDeprecatedFitMethod,
+                             "sample_weight"), \
+        "has_fit_parameter fails for class with deprecated fit method."
+
 
 def test_check_symmetric():
     arr_sym = np.array([[0, 1], [1, 2]])