MNT Fixes pytest by using deprecated_modules (scikit-learn#15291)

* MNT Uses gitignore to filter pytest

* MNT Uses collect_ignore_glob to configure collect_ignore_glob

* CLN Restrict to py file

* DOC Remove comments

* ENH Adds neural network

* CLN Proper import

* CLN Proper import

* DOC Adds comments

.gitignore

@@ -93,6 +93,9 @@ sklearn/ensemble/weight_boosting.py
 sklearn/tree/export.py
 sklearn/tree/tree.py
 
+sklearn/neural_network/rbm.py
+sklearn/neural_network/multilayer_perceptron.py
+
 sklearn/utils/weight_vector.py
 sklearn/utils/seq_dataset.py
 sklearn/utils/fast_dict.py

conftest.py

@@ -7,13 +7,15 @@
 
 import platform
 from distutils.version import LooseVersion
+import os
 
 import pytest
 from _pytest.doctest import DoctestItem
 
 from sklearn import set_config
 from sklearn.utils import _IS_32BIT
 from sklearn.externals import _pilutil
+from sklearn._build_utils.deprecated_modules import _DEPRECATED_MODULES
 
 PYTEST_MIN_VERSION = '3.3.0'
 
@@ -96,3 +98,10 @@ def pytest_runtest_setup(item):
 def pytest_runtest_teardown(item, nextitem):
     if isinstance(item, DoctestItem):
         set_config(print_changed_only=False)
+
+
+# TODO: Remove when modules are deprecated in 0.24
+# Configures pytest to ignore deprecated modules.
+collect_ignore_glob = [
+    os.path.join(*deprecated_path.split(".")) + ".py"
+    for _, deprecated_path, _ in _DEPRECATED_MODULES]

sklearn/_build_utils/deprecated_modules.py

@@ -20,6 +20,10 @@
     ('_classes', 'sklearn.tree.tree', 'sklearn.tree'),
     ('_export', 'sklearn.tree.export', 'sklearn.tree'),
 
+    ('_rbm', 'sklearn.neural_network.rbm', 'sklearn.neural_network'),
+    ('_multilayer_perceptron',
+     'sklearn.neural_network.multilayer_perceptron', 'sklearn.neural_network'),
+
     ('_weight_vector', 'sklearn.utils.weight_vector', 'sklearn.utils'),
     ('_seq_dataset', 'sklearn.utils.seq_dataset', 'sklearn.utils'),
     ('_fast_dict', 'sklearn.utils.fast_dict', 'sklearn.utils'),

sklearn/cluster/_birch.py

@@ -14,7 +14,7 @@
 from ..utils.extmath import row_norms, safe_sparse_dot
 from ..utils.validation import check_is_fitted
 from ..exceptions import ConvergenceWarning
-from ._hierarchical import AgglomerativeClustering
+from . import AgglomerativeClustering
 
 
 def _iterate_sparse_X(X):

sklearn/cluster/tests/test_hierarchical.py

@@ -23,8 +23,7 @@
 from sklearn.cluster import ward_tree
 from sklearn.cluster import AgglomerativeClustering, FeatureAgglomeration
 from sklearn.cluster._hierarchical import (_hc_cut, _TREE_BUILDERS,
-                                           _fix_connectivity)
-from sklearn.cluster.hierarchical import linkage_tree
+                                           linkage_tree, _fix_connectivity)
 from sklearn.feature_extraction.image import grid_to_graph
 from sklearn.metrics.pairwise import PAIRED_DISTANCES, cosine_distances,\
     manhattan_distances, pairwise_distances

sklearn/utils/deprecation.py

@@ -128,9 +128,6 @@ def _raise_dep_warning_if_not_pytest(deprecated_path, correct_path):
     # Raise a deprecation warning with standardized deprecation message.
     # Useful because we are now deprecating # anything that isn't explicitly
     # in an __init__ file.
-    # We don't want to raise a dep warning if we are in a pytest session else
-    # the CIs with -Werror::DeprecationWarning would fail. The deprecations are
-    # still properly tested in sklearn/tests/test_import_deprecations.py
 
     # TODO: remove in 0.24 since this shouldn't be needed anymore.
 
@@ -143,5 +140,4 @@ def _raise_dep_warning_if_not_pytest(deprecated_path, correct_path):
         "part of the private API."
     ).format(deprecated_path=deprecated_path, correct_path=correct_path)
 
-    if not getattr(sys, '_is_pytest_session', False):
-        warnings.warn(message, DeprecationWarning)
+    warnings.warn(message, DeprecationWarning)