scikit-learn · ogrisel · Jan 13, 2021 · Jan 5, 2021 · Jan 6, 2021 · Jan 6, 2021
diff --git a/conftest.py b/conftest.py
@@ -5,7 +5,6 @@
 # doc/modules/clustering.rst and use sklearn from the local folder rather than
 # the one from site-packages.
 
-import os
 import platform
 import sys
 
@@ -17,18 +16,12 @@
 from sklearn._min_dependencies import PYTEST_MIN_VERSION
 from sklearn.utils.fixes import np_version, parse_version
 
-
 if parse_version(pytest.__version__) < parse_version(PYTEST_MIN_VERSION):
     raise ImportError('Your version of pytest is too old, you should have '
                       'at least pytest >= {} installed.'
                       .format(PYTEST_MIN_VERSION))
 
 
-def pytest_addoption(parser):
-    parser.addoption("--skip-network", action="store_true", default=False,
-                     help="skip network tests")
-
-
 def pytest_collection_modifyitems(config, items):
     for item in items:
         # FeatureHasher is not compatible with PyPy
@@ -50,15 +43,6 @@ def pytest_collection_modifyitems(config, items):
             )
             item.add_marker(marker)
 
-    # Skip tests which require internet if the flag is provided
-    if (config.getoption("--skip-network")
-            or int(os.environ.get("SKLEARN_SKIP_NETWORK_TESTS", "0"))):
-        skip_network = pytest.mark.skip(
-            reason="test requires internet connectivity")
-        for item in items:
-            if "network" in item.keywords:
-                item.add_marker(skip_network)
-
     # numpy changed the str/repr formatting of numpy arrays in 1.14. We want to
     # run doctests only for numpy >= 1.14.
     skip_doctests = False

diff --git a/doc/computing/parallelism.rst b/doc/computing/parallelism.rst
@@ -212,4 +212,5 @@ These environment variables should be set before importing scikit-learn.
 :SKLEARN_SKIP_NETWORK_TESTS:
 
     When this environment variable is set to a non zero value, the tests
-    that need network access are skipped.
+    that need network access are skipped. When this environment variable is
+    not set then network tests are skipped.
diff --git a/sklearn/conftest.py b/sklearn/conftest.py
@@ -1,9 +1,94 @@
 import os
+from os import environ
+from functools import wraps
 
 import pytest
 from threadpoolctl import threadpool_limits
 
 from sklearn.utils._openmp_helpers import _openmp_effective_n_threads
+from sklearn.datasets import fetch_20newsgroups
+from sklearn.datasets import fetch_20newsgroups_vectorized
+from sklearn.datasets import fetch_california_housing
+from sklearn.datasets import fetch_covtype
+from sklearn.datasets import fetch_kddcup99
+from sklearn.datasets import fetch_olivetti_faces
+from sklearn.datasets import fetch_rcv1
+
+
+dataset_fetchers = {
+    'fetch_20newsgroups_fxt': fetch_20newsgroups,
+    'fetch_20newsgroups_vectorized_fxt': fetch_20newsgroups_vectorized,
+    'fetch_california_housing_fxt': fetch_california_housing,
+    'fetch_covtype_fxt': fetch_covtype,
+    'fetch_kddcup99_fxt': fetch_kddcup99,
+    'fetch_olivetti_faces_fxt': fetch_olivetti_faces,
+    'fetch_rcv1_fxt': fetch_rcv1,
+}
+
+
+def _fetch_fixture(f):
+    """Fetch dataset (download if missing and requested by environment)."""
+    download_if_missing = environ.get('SKLEARN_SKIP_NETWORK_TESTS', '1') == '0'
+
+    @wraps(f)
+    def wrapped(*args, **kwargs):
+        kwargs['download_if_missing'] = download_if_missing
+        try:
+            return f(*args, **kwargs)
+        except IOError:
+            pytest.skip("test is enabled when SKLEARN_SKIP_NETWORK_TESTS=0")
+    return pytest.fixture(lambda: wrapped)
+
+
+# Adds fixtures for fetching data
+fetch_20newsgroups_fxt = _fetch_fixture(fetch_20newsgroups)
+fetch_20newsgroups_vectorized_fxt = \
+    _fetch_fixture(fetch_20newsgroups_vectorized)
+fetch_california_housing_fxt = _fetch_fixture(fetch_california_housing)
+fetch_covtype_fxt = _fetch_fixture(fetch_covtype)
+fetch_kddcup99_fxt = _fetch_fixture(fetch_kddcup99)
+fetch_olivetti_faces_fxt = _fetch_fixture(fetch_olivetti_faces)
+fetch_rcv1_fxt = _fetch_fixture(fetch_rcv1)
+
+
+def pytest_collection_modifyitems(config, items):
+    """Called after collect is completed.
+
+    Parameters
+    ----------
+    config : pytest config
+    items : list of collected items
+    """
+    run_network_tests = environ.get('SKLEARN_SKIP_NETWORK_TESTS', '1') == '0'
+    skip_network = pytest.mark.skip(
+        reason="test is enabled when SKLEARN_SKIP_NETWORK_TESTS=0")
+
+    # download datasets during collection to avoid thread unsafe behavior
+    # when running pytest in parallel with pytest-xdist
+    dataset_features_set = set(dataset_fetchers)
+    datasets_to_download = set()
+
+    for item in items:
+        if not hasattr(item, "fixturenames"):
+            continue
+        item_fixtures = set(item.fixturenames)
+        dataset_to_fetch = item_fixtures & dataset_features_set
+        if not dataset_to_fetch:
+            continue
+
+        if run_network_tests:
+            datasets_to_download |= dataset_to_fetch
+        else:
+            # network tests are skipped
+            item.add_marker(skip_network)
+
+    # Only download datasets on the first worker spawned by pytest-xdist
+    # to avoid thread unsafe behavior. If pytest-xdist is not used, we still
+    # download before tests run.
+    worker_id = environ.get("PYTEST_XDIST_WORKER", "gw0")
+    if worker_id == "gw0" and run_network_tests:
+        for name in datasets_to_download:
+            dataset_fetchers[name]()
 
 
 @pytest.fixture(scope='function')

diff --git a/sklearn/datasets/tests/conftest.py b/sklearn/datasets/tests/conftest.py
@@ -1,67 +1,7 @@
 """ Network tests are only run, if data is already locally available,
 or if download is specifically requested by environment variable."""
 import builtins
-from functools import wraps
-from os import environ
 import pytest
-from sklearn.datasets import fetch_20newsgroups
-from sklearn.datasets import fetch_20newsgroups_vectorized
-from sklearn.datasets import fetch_california_housing
-from sklearn.datasets import fetch_covtype
-from sklearn.datasets import fetch_kddcup99
-from sklearn.datasets import fetch_olivetti_faces
-from sklearn.datasets import fetch_rcv1
-
-
-def _wrapped_fetch(f, dataset_name):
-    """ Fetch dataset (download if missing and requested by environment) """
-    download_if_missing = environ.get('SKLEARN_SKIP_NETWORK_TESTS', '1') == '0'
-
-    @wraps(f)
-    def wrapped(*args, **kwargs):
-        kwargs['download_if_missing'] = download_if_missing
-        try:
-            return f(*args, **kwargs)
-        except IOError:
-            pytest.skip("Download {} to run this test".format(dataset_name))
-    return wrapped
-
-
-@pytest.fixture
-def fetch_20newsgroups_fxt():
-    return _wrapped_fetch(fetch_20newsgroups, dataset_name='20newsgroups')
-
-
-@pytest.fixture
-def fetch_20newsgroups_vectorized_fxt():
-    return _wrapped_fetch(fetch_20newsgroups_vectorized,
-                          dataset_name='20newsgroups_vectorized')
-
-
-@pytest.fixture
-def fetch_california_housing_fxt():
-    return _wrapped_fetch(fetch_california_housing,
-                          dataset_name='california_housing')
-
-
-@pytest.fixture
-def fetch_covtype_fxt():
-    return _wrapped_fetch(fetch_covtype, dataset_name='covtype')
-
-
-@pytest.fixture
-def fetch_kddcup99_fxt():
-    return _wrapped_fetch(fetch_kddcup99, dataset_name='kddcup99')
-
-
-@pytest.fixture
-def fetch_olivetti_faces_fxt():
-    return _wrapped_fetch(fetch_olivetti_faces, dataset_name='olivetti_faces')
-
-
-@pytest.fixture
-def fetch_rcv1_fxt():
-    return _wrapped_fetch(fetch_rcv1, dataset_name='rcv1')
 
 
 @pytest.fixture

diff --git a/sklearn/ensemble/tests/test_gradient_boosting.py b/sklearn/ensemble/tests/test_gradient_boosting.py
@@ -13,7 +13,7 @@
 
 from sklearn import datasets
 from sklearn.base import clone
-from sklearn.datasets import (make_classification, fetch_california_housing,
+from sklearn.datasets import (make_classification,
                               make_regression)
 from sklearn.ensemble import GradientBoostingClassifier
 from sklearn.ensemble import GradientBoostingRegressor
@@ -345,16 +345,15 @@ def test_max_feature_regression():
     assert deviance < 0.5, "GB failed with deviance %.4f" % deviance
 
 
-@pytest.mark.network
-def test_feature_importance_regression():
+def test_feature_importance_regression(fetch_california_housing_fxt):
     """Test that Gini importance is calculated correctly.
 
     This test follows the example from [1]_ (pg. 373).
 
     .. [1] Friedman, J., Hastie, T., & Tibshirani, R. (2001). The elements
        of statistical learning. New York: Springer series in statistics.
     """
-    california = fetch_california_housing()
+    california = fetch_california_housing_fxt()
     X, y = california.data, california.target
     X_train, X_test, y_train, y_test = train_test_split(X, y, random_state=0)