fixes per feedback

Author: Venkat Venkataraju

setup.py

@@ -27,6 +27,9 @@
 
 from u2flib_host.yubicommon.setup import setup
 
+tests_require = ['cryptography>=1.0']
+if (sys.version_info < (3, 3)):
+    tests_require.append('mock')
 
 setup(
     name='python-u2flib-host',
@@ -44,7 +47,7 @@
             'u2f-authenticate=u2flib_host.authenticate:main',
         ],
     },
-    tests_require=['cryptography>=1.0'],
+    tests_require=tests_require,
     extras_require={
         'soft_device': ['cryptography>=1.0'],
     },

test/test_hid_transport.py

@@ -3,9 +3,13 @@
 from u2flib_host import hid_transport
 from u2flib_host import exc
 from u2flib_host.yubicommon.compat import byte2int, int2byte
-from mock import patch
 
-class TestHIDDevice():
+try:
+    from unittest.mock import patch
+except ImportError:
+    from mock import patch
+
+class TestHIDDevice(object):
     def write(self, payload):
         self.cid = payload[1:5]
         self.cmd = payload[5] ^ hid_transport.TYPE_INIT
@@ -46,7 +50,7 @@ def test_init(self):
             dev.init()
             self.assertEqual(dev.capabilities, 0x05)
 
-    def test_init_invalid_nounce(self):
+    def test_init_invalid_nonce(self):
         with patch.object(os, 'urandom', return_value=(b'\xab'*8)) as mock_method:
             hid_device = TestHIDDevice()
             hid_device.response = HIDDeviceTest.build_response(