MAINT: skip doctest for Python 2 (scikit-learn#12074)

conftest.py

@@ -11,6 +11,8 @@
 import pytest
 from _pytest.doctest import DoctestItem
 
+from sklearn.utils.fixes import PY3_OR_LATER
+
 PYTEST_MIN_VERSION = '3.3.0'
 
 if LooseVersion(pytest.__version__) < PYTEST_MIN_VERSION:
@@ -28,18 +30,21 @@ def pytest_collection_modifyitems(config, items):
                 item.add_marker(skip_marker)
 
     # numpy changed the str/repr formatting of numpy arrays in 1.14. We want to
-    # run doctests only for numpy >= 1.14.
-    skip_doctests = True
+    # run doctests only for numpy >= 1.14. We want to skip the doctest for
+    # python 2 due to unicode.
+    skip_doctests = False
+    if not PY3_OR_LATER:
+        skip_doctests = True
     try:
         import numpy as np
-        if LooseVersion(np.__version__) >= LooseVersion('1.14'):
-            skip_doctests = False
+        if LooseVersion(np.__version__) < LooseVersion('1.14'):
+            skip_doctests = True
     except ImportError:
         pass
 
     if skip_doctests:
         skip_marker = pytest.mark.skip(
-            reason='doctests are only run for numpy >= 1.14')
+            reason='doctests are only run for numpy >= 1.14 and python >= 3')
 
         for item in items:
             if isinstance(item, DoctestItem):