Remove mock from tests requirements

setup.py

@@ -116,5 +116,4 @@ setup(name=name,
     zip_safe=False,
     test_suite='trytond.tests',
     test_loader='trytond.test_loader:Loader',
-    tests_require=['mock'],
     )

tox.ini

@@ -4,7 +4,6 @@ envlist = {py34,py35,py36}-{sqlite,postgresql},pypy3-{sqlite,postgresql}
 [testenv]
 commands = {envpython} setup.py test
 deps =
-    mock
     {py34,py35,py36}-postgresql: psycopg2 >= 2.5
     pypy3-postgresql: psycopg2cffi >= 2.5
     sqlite: sqlitebck

trytond/tests/test_user.py

@@ -3,10 +3,7 @@
 import datetime
 import os
 import unittest
-try:
-    from unittest.mock import patch, ANY
-except ImportError:
-    from mock import patch, ANY
+from unittest.mock import patch, ANY
 
 from trytond.tests.test_tryton import activate_module, with_transaction
 from trytond.pool import Pool