start adding config tests

tests/integration/test_config.py

@@ -0,0 +1,14 @@
+import json
+import urllib2
+import vcr
+
+def test_set_serializer_default_config(tmpdir):
+    my_vcr = vcr.VCR(serializer='json')
+
+    with my_vcr.use_cassette(str(tmpdir.join('test.json'))) as cass:
+        assert my_vcr.serializer == 'json'
+        urllib2.urlopen('http://httpbin.org/get')
+
+    with open(str(tmpdir.join('test.json'))) as f:
+        assert json.loads(f.read())
+