MNT: reduce the number of warnings in test_common.py (#11151)

Shangwu Yao · lesteve · commit cb1dbc25a7a2 · 2018-06-11T08:59:12.000+02:00
Improve handling of warning filters in sklearn.utils.testing by avoiding to reset warnings.filters.
diff --git a/sklearn/gaussian_process/tests/test_gaussian_process.py b/sklearn/gaussian_process/tests/test_gaussian_process.py
@@ -15,6 +15,7 @@
 from sklearn.datasets import make_regression
 from sklearn.utils.testing import assert_greater, assert_true, assert_raises
 
+pytestmark = pytest.mark.filterwarnings('ignore', category=DeprecationWarning)
 
 f = lambda x: x * np.sin(x)
 X = np.atleast_2d([1., 3., 5., 6., 7., 8.]).T
diff --git a/sklearn/tests/test_common.py b/sklearn/tests/test_common.py
@@ -22,6 +22,7 @@
 from sklearn.utils.testing import assert_greater
 from sklearn.utils.testing import assert_in
 from sklearn.utils.testing import ignore_warnings
+from sklearn.exceptions import ConvergenceWarning
 
 import sklearn
 from sklearn.cluster.bicluster import BiclusterMixin
@@ -91,18 +92,22 @@ def _rename_partial(val):
 )
 def test_non_meta_estimators(name, Estimator, check):
     # Common tests for non-meta estimators
-    estimator = Estimator()
-    set_checking_parameters(estimator)
-    check(name, estimator)
+    with ignore_warnings(category=(DeprecationWarning, ConvergenceWarning,
+                                   UserWarning, FutureWarning)):
+        estimator = Estimator()
+        set_checking_parameters(estimator)
+        check(name, estimator)
 
 
 @pytest.mark.parametrize("name, Estimator",
                          _tested_non_meta_estimators())
 def test_no_attributes_set_in_init(name, Estimator):
     # input validation etc for non-meta estimators
-    estimator = Estimator()
-    # check this on class
-    check_no_attributes_set_in_init(name, estimator)
+    with ignore_warnings(category=(DeprecationWarning, ConvergenceWarning,
+                                   UserWarning, FutureWarning)):
+        estimator = Estimator()
+        # check this on class
+        check_no_attributes_set_in_init(name, estimator)
 
 
 def test_configure():
diff --git a/sklearn/utils/estimator_checks.py b/sklearn/utils/estimator_checks.py
@@ -301,10 +301,10 @@ def check_estimator(Estimator):
     for check in _yield_all_checks(name, estimator):
         try:
             check(name, estimator)
-        except SkipTest as message:
+        except SkipTest as exception:
             # the only SkipTest thrown currently results from not
             # being able to import pandas.
-            warnings.warn(message, SkipTestWarning)
+            warnings.warn(str(exception), SkipTestWarning)
 
 
 def _boston_subset(n_samples=200):
@@ -327,7 +327,6 @@ def set_checking_parameters(estimator):
             and not isinstance(estimator, BaseSGD)):
         estimator.set_params(n_iter=5)
     if "max_iter" in params:
-        warnings.simplefilter("ignore", ConvergenceWarning)
         if estimator.max_iter is not None:
             estimator.set_params(max_iter=min(5, estimator.max_iter))
         # LinearSVR, LinearSVC
diff --git a/sklearn/utils/testing.py b/sklearn/utils/testing.py
@@ -137,7 +137,6 @@ def assert_warns(warning_class, func, *args, **kw):
     result : the return value of `func`
 
     """
-    # very important to avoid uncontrolled state propagation
     clean_warning_registry()
     with warnings.catch_warnings(record=True) as w:
         # Cause all warnings to always be triggered.
@@ -321,7 +320,6 @@ def __call__(self, fn):
         """Decorator to catch and hide warnings without visual nesting."""
         @wraps(fn)
         def wrapper(*args, **kwargs):
-            # very important to avoid uncontrolled state propagation
             clean_warning_registry()
             with warnings.catch_warnings():
                 warnings.simplefilter("ignore", self.category)
@@ -339,22 +337,22 @@ def __repr__(self):
         return "%s(%s)" % (name, ", ".join(args))
 
     def __enter__(self):
-        clean_warning_registry()  # be safe and not propagate state + chaos
-        warnings.simplefilter("ignore", self.category)
         if self._entered:
             raise RuntimeError("Cannot enter %r twice" % self)
         self._entered = True
         self._filters = self._module.filters
         self._module.filters = self._filters[:]
         self._showwarning = self._module.showwarning
+        clean_warning_registry()
+        warnings.simplefilter("ignore", self.category)
 
     def __exit__(self, *exc_info):
         if not self._entered:
             raise RuntimeError("Cannot exit %r without entering first" % self)
         self._module.filters = self._filters
         self._module.showwarning = self._showwarning
         self.log[:] = []
-        clean_warning_registry()  # be safe and not propagate state + chaos
+        clean_warning_registry()
 
 
 assert_less = _dummy.assertLess
@@ -724,8 +722,13 @@ def run_test(*args, **kwargs):
 
 
 def clean_warning_registry():
-    """Safe way to reset warnings."""
-    warnings.resetwarnings()
+    """Clean Python warning registry for easier testing of warning messages.
+
+    We may not need to do this any more when getting rid of Python 2, not
+    entirely sure. See https://bugs.python.org/issue4180 and
+    https://bugs.python.org/issue21724 for more details.
+
+    """
     reg = "__warningregistry__"
     for mod_name, mod in list(sys.modules.items()):
         if 'six.moves' in mod_name:
diff --git a/sklearn/utils/tests/test_testing.py b/sklearn/utils/tests/test_testing.py
@@ -211,26 +211,19 @@ def context_manager_no_user_multiple_warning():
     assert_warns(DeprecationWarning, context_manager_no_user_multiple_warning)
 
 
-# This class is inspired from numpy 1.7 with an alteration to check
-# the reset warning filters after calls to assert_warns.
-# This assert_warns behavior is specific to scikit-learn because
-# `clean_warning_registry()` is called internally by assert_warns
-# and clears all previous filters.
 class TestWarns(unittest.TestCase):
     def test_warn(self):
         def f():
             warnings.warn("yo")
             return 3
 
-        # Test that assert_warns is not impacted by externally set
-        # filters and is reset internally.
-        # This is because `clean_warning_registry()` is called internally by
-        # assert_warns and clears all previous filters.
-        warnings.simplefilter("ignore", UserWarning)
-        assert_equal(assert_warns(UserWarning, f), 3)
-
-        # Test that the warning registry is empty after assert_warns
-        assert_equal(sys.modules['warnings'].filters, [])
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", UserWarning)
+            filters_orig = warnings.filters[:]
+            assert_equal(assert_warns(UserWarning, f), 3)
+            # test that assert_warns doesn't have side effects on warnings
+            # filters
+            assert_equal(warnings.filters, filters_orig)
 
         assert_raises(AssertionError, assert_no_warnings, f)
         assert_equal(assert_no_warnings(lambda x: x, 1), 1)
