use conditional requirements for backport libraries Fixes #147

vcr/cassette.py

@@ -2,14 +2,11 @@
 import functools
 import logging
 
-import contextlib2
+
 import wrapt
-try:
-    from collections import Counter
-except ImportError:
-    from backport_collections import Counter
 
 # Internal imports
+from .compat import contextlib, collections
 from .errors import UnhandledHTTPRequestError
 from .matchers import requests_match, uri, method
 from .patch import CassettePatcherBuilder
@@ -43,7 +40,7 @@ class CassetteContextDecorator(object):
         self.__finish = None
 
     def _patch_generator(self, cassette):
-        with contextlib2.ExitStack() as exit_stack:
+        with contextlib.ExitStack() as exit_stack:
             for patcher in CassettePatcherBuilder(cassette).build():
                 exit_stack.enter_context(patcher)
             log.debug('Entered context for cassette at {0}.'.format(cassette._path))
@@ -148,7 +145,7 @@ class Cassette(object):
 
         # self.data is the list of (req, resp) tuples
         self.data = []
-        self.play_counts = Counter()
+        self.play_counts = collections.Counter()
         self.dirty = False
         self.rewound = False
 

vcr/compat.py

@@ -0,0 +1,18 @@
+try:
+    from unittest import mock
+except ImportError:
+    import mock
+
+try:
+    import contextlib
+except ImportError:
+    import contextlib2 as contextlib
+else:
+    if not hasattr(contextlib, 'ExitStack'):
+        import contextlib2 as contextlib
+
+import collections
+if not hasattr(collections, 'Counter'):
+    import backport_collections as collections
+
+__all__ = ['mock', 'contextlib', 'collections']

vcr/config.py

@@ -1,4 +1,3 @@
-import collections
 import copy
 import functools
 import inspect
@@ -6,6 +5,7 @@ import os
 
 import six
 
+from .compat import collections
 from .cassette import Cassette
 from .serializers import yamlserializer, jsonserializer
 from .util import compose

vcr/filters.py

@@ -1,12 +1,10 @@
 from six import BytesIO, text_type
 from six.moves.urllib.parse import urlparse, urlencode, urlunparse
-try:
-    from collections import OrderedDict
-except ImportError:
-    from backport_collections import OrderedDict
 import copy
 import json
 
+from .compat import collections
+
 
 def remove_headers(request, headers_to_remove):
     headers = copy.copy(request.headers)
@@ -40,7 +38,7 @@ def remove_post_data_parameters(request, post_data_parameters_to_remove):
                     del json_data[k]
             request.body = json.dumps(json_data).encode('utf-8')
         else:
-            post_data = OrderedDict()
+            post_data = collections.OrderedDict()
             if isinstance(request.body, text_type):
                 request.body = request.body.encode('utf-8')
 

vcr/patch.py

@@ -2,9 +2,7 @@
 import functools
 import itertools
 
-import contextlib2
-import mock
-
+from .compat import contextlib, mock
 from .stubs import VCRHTTPConnection, VCRHTTPSConnection
 from six.moves import http_client as httplib
 
@@ -323,9 +321,9 @@ def reset_patchers():
                                 _CertValidatingHTTPSConnection)
 
 
-@contextlib2.contextmanager
+@contextlib.contextmanager
 def force_reset():
-    with contextlib2.ExitStack() as exit_stack:
+    with contextlib.ExitStack() as exit_stack:
         for patcher in reset_patchers():
             exit_stack.enter_context(patcher)
         yield