Enable compatibility with Python 3.9 (tested)

.travis.yml

@@ -6,6 +6,8 @@ python:
   - "3.4"
   - "3.5"
   - "3.6"
+  - "3.7"
+  - "3.8"
   - "pypy"
   - "pypy3.3-5.2-alpha1"
 

flask_frozen/__init__.py

@@ -26,9 +26,14 @@
 from unicodedata import normalize
 from threading import Lock
 from contextlib import contextmanager
-from collections import Mapping, namedtuple
 from posixpath import relpath as posix_relpath
 
+from collections import namedtuple
+try:
+    from collections.abc import Mapping  # Python 3
+except ImportError:
+    from collections import Mapping  # Python 2.7
+
 try:
     from urllib import unquote
     from urlparse import urlsplit

flask_frozen/tests.py

@@ -23,6 +23,8 @@
 from contextlib import contextmanager
 from unicodedata import normalize
 from warnings import catch_warnings
+import sys
+import subprocess
 
 from flask_frozen import (Freezer, walk_directory,
     FrozenFlaskWarning, MissingURLGeneratorWarning, MimetypeMismatchWarning,
@@ -524,6 +526,14 @@ def view_post():
             self.assertEqual(first_mtimes['epoch'],second_mtimes['epoch'])
             self.assertNotEqual(first_mtimes['now'],second_mtimes['now'])
 
+class TestPythonCompatibilityWarnings(unittest.TestCase):
+    def test_importing_collections(self):
+        ps = subprocess.check_output([sys.executable, 'flask_frozen/__init__.py'],
+                                     stderr=subprocess.STDOUT)
+        stderr = ps.decode('utf-8').lower()
+        assert 'deprecationwarning' not in stderr
+        assert 'using or importing the abcs' not in stderr
+
 # with_no_argument_rules=False and with_static_files=False are
 # not tested as they produces (expected!) warnings
 

setup.py

@@ -56,6 +56,8 @@
         'Programming Language :: Python :: 3.4',
         'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.7',
+        'Programming Language :: Python :: 3.8',
         'Topic :: Internet :: WWW/HTTP :: Dynamic Content',
         'Topic :: Software Development :: Libraries :: Python Modules'
     ]

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py26, py27, py34, py35, py36, pypy, pypy3
+envlist = py26, py27, py34, py35, py36, py37, py38, pypy, pypy3
 [testenv]
 commands=python -m flask_frozen.tests
 changedir=docs