Deprecate support for Python 3.5 and earlier

Author: sethmlarson

elasticsearch/__init__.py

@@ -104,3 +104,13 @@
     ]
 except (ImportError, SyntaxError):
     pass
+
+# Python earlier than 3.6 is deprecated and will be removed in 8.0.0
+if sys.version_info < (3, 6):
+    warnings.warn(
+        "Support for Python 3.5 and earlier is deprecated and will be removed "
+        "in v8.0.0 (current instance is Python %d.%d) See https://github.com/elastic"
+        "/elasticsearch-py/issues/1696 for details." % sys.version_info[:2],
+        category=DeprecationWarning,
+        stacklevel=2,
+    )

test_elasticsearch/test_module.py

@@ -0,0 +1,53 @@
+#  Licensed to Elasticsearch B.V. under one or more contributor
+#  license agreements. See the NOTICE file distributed with
+#  this work for additional information regarding copyright
+#  ownership. Elasticsearch B.V. licenses this file to you under
+#  the Apache License, Version 2.0 (the "License"); you may
+#  not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+# 	http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing,
+#  software distributed under the License is distributed on an
+#  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+#  KIND, either express or implied.  See the License for the
+#  specific language governing permissions and limitations
+#  under the License.
+
+import importlib
+import sys
+import warnings
+
+import pytest
+
+import elasticsearch
+
+
+@pytest.mark.skipif(sys.version_info < (3, 6), reason="Requires Python 3.6+")
+def test_no_deprecation_python3_6_and_later():
+    with warnings.catch_warnings(record=True) as w:
+        importlib.reload(elasticsearch)
+
+    assert len(w) == 0
+
+
+@pytest.mark.skipif(sys.version_info >= (3, 6), reason="Requires Python <3.6")
+def test_deprecated_python3_5_and_earlier():
+
+    try:  # Python 3.4+
+        import imp
+
+        reload = imp.reload
+    except ImportError:  # Python 2.7
+        reload = reload
+
+    with pytest.warns(DeprecationWarning) as w:
+        reload(elasticsearch)
+
+    assert len(w) == 1
+    assert str(w[0].message) == (
+        "Support for Python 3.5 and earlier is deprecated and will be removed "
+        "in v8.0.0 (current instance is Python %d.%d) See https://github.com/"
+        "elastic/elasticsearch-py/issues/1696 for details." % (sys.version_info[:2])
+    )