Fix DeprecationWarning on python 3.7 for python 3.8

 - got this with version 3.7.3 of python so fixed it
 - add python 3.7 to travis
 - ensure the retro compatibility with pypy and python 2.7
 - bump version to 3.0.8

.travis.yml

@@ -9,6 +9,15 @@ python:
   - '3.6'
   - pypy
 
+# from https://github.com/travis-ci/travis-ci/issues/9815
+# https://github.com/travis-ci/travis-ci/issues/9069#issuecomment-425720905
+# Enable 3.7 without globally enabling sudo and dist: xenial for other build jobs
+matrix:
+  include:
+    - python: 3.7
+      dist: xenial
+      sudo: true
+
 env:
 - FLASK=0.10.1
 - FLASK=0.10

CHANGELOG.md

@@ -1,5 +1,8 @@
 # Change Log
 
+## 3.0.8
+DeprecationWarning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated, and in 3.8 it will stop working
+
 ## 3.0.7
 Updated logging.warn to logging.warning (#234) Thanks Vaibhav
 

flask_cors/core.py

@@ -9,7 +9,12 @@
 """
 import re
 import logging
-import collections
+try:
+    # on python 3
+    from collections.abc import Iterable
+except ImportError:
+    # on python 2.7 and pypy
+    from collections import Iterable
 from datetime import timedelta
 from six import string_types
 from flask import request, current_app
@@ -78,7 +83,7 @@ def pattern_length(pair):
     elif isinstance(resources, string_types):
         return [(re_fix(resources), {})]
 
-    elif isinstance(resources, collections.Iterable):
+    elif isinstance(resources, Iterable):
         return [(re_fix(r), {}) for r in resources]
 
     # Type of compiled regex is not part of the public API. Test for this
@@ -319,7 +324,7 @@ def flexible_str(obj):
     if obj is None:
         return None
     elif(not isinstance(obj, string_types)
-            and isinstance(obj, collections.Iterable)):
+            and isinstance(obj, Iterable)):
         return ', '.join(str(item) for item in sorted(obj))
     else:
         return str(obj)
@@ -337,7 +342,7 @@ def ensure_iterable(inst):
     """
     if isinstance(inst, string_types):
         return [inst]
-    elif not isinstance(inst, collections.Iterable):
+    elif not isinstance(inst, Iterable):
         return [inst]
     else:
         return inst

flask_cors/version.py

@@ -1 +1 @@
-__version__ = '3.0.7'
+__version__ = '3.0.8'