tests: Import mock with a compatibility helper

Make sure that mock is imported from the unittest lib on Python 3,
because that's its location on Python 3.

The mock library is needed for testing on Python 3 too, since otherwise
`import mock` raises an ImportError.

Author: suutari-ai

database_sanitizer/tests/_compat.py

@@ -0,0 +1,6 @@
+try:
+    from unittest import mock
+except ImportError:
+    import mock
+
+__all__ = ['mock']

database_sanitizer/tests/test_config.py

@@ -8,10 +8,7 @@
 
 from ..config import Configuration, ConfigurationError
 
-try:
-    from unittest import mock
-except ImportError:
-    import mock
+from ._compat import mock
 
 
 def test_load_config_data_must_be_dict():

database_sanitizer/tests/test_dump_postgres.py

@@ -13,10 +13,7 @@
 from ..dump import postgres as dump_postgres
 from ..utils.postgres import decode_copy_value
 
-try:
-    from unittest import mock
-except ImportError:
-    import mock
+from ._compat import mock
 
 
 MOCK_PG_DUMP_OUTPUT = b"""

database_sanitizer/tests/test_sanitizers_string.py

@@ -2,10 +2,10 @@
 
 from __future__ import unicode_literals
 
-import mock
 import pytest
 
 from ..sanitizers.string import sanitize_empty, sanitize_random, sanitize_zfill
+from ._compat import mock
 
 
 @pytest.mark.parametrize(

database_sanitizer/tests/test_sanitizers_times.py

@@ -1,9 +1,9 @@
 import datetime
 
-import mock
-
 from database_sanitizer.sanitizers import times
 
+from ._compat import mock
+
 
 class _FakeDateTime(datetime.datetime):
     @staticmethod