Add tests.alter_time and fix time altering on pypy.

1 files changed, 113 insertions, 0 deletions

diff --git a/tests/alter_time.py b/tests/alter_time.py
new file mode 100644
index 0000000..f426e03
--- /dev/null
+++ b/tests/alter_time.py
@@ -0,0 +1,113 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+# This code is in the public domain
+# Author: Raphaël Barrois
+
+
+from __future__ import print_function
+
+import datetime
+import mock
+
+
+real_datetime_class = datetime.datetime
+
+def mock_datetime_now(target, datetime_module):
+    """Override ``datetime.datetime.now()`` with a custom target value.
+
+    This creates a new datetime.datetime class, and alters its now()/utcnow()
+    methods.
+
+    Returns:
+        A mock.patch context, can be used as a decorator or in a with.
+    """
+
+    # See http://bugs.python.org/msg68532
+    # And http://docs.python.org/reference/datamodel.html#customizing-instance-and-subclass-checks
+    class DatetimeSubclassMeta(type):
+        """We need to customize the __instancecheck__ method for isinstance().
+
+        This must be performed at a metaclass level.
+        """
+
+        @classmethod
+        def __instancecheck__(mcs, obj):
+            return isinstance(obj, real_datetime_class)
+
+    class BaseMockedDatetime(real_datetime_class):
+        @classmethod
+        def now(cls, tz=None):
+            return target.replace(tzinfo=tz)
+
+        @classmethod
+        def utcnow(cls):
+            return target
+
+    # Python2 & Python3-compatible metaclass
+    MockedDatetime = DatetimeSubclassMeta('datetime', (BaseMockedDatetime,), {})
+
+    return mock.patch.object(datetime_module, 'datetime', MockedDatetime)
+
+real_date_class = datetime.date
+
+def mock_date_today(target, datetime_module):
+    """Override ``datetime.date.today()`` with a custom target value.
+
+    This creates a new datetime.date class, and alters its today() method.
+
+    Returns:
+        A mock.patch context, can be used as a decorator or in a with.
+    """
+
+    # See http://bugs.python.org/msg68532
+    # And http://docs.python.org/reference/datamodel.html#customizing-instance-and-subclass-checks
+    class DateSubclassMeta(type):
+        """We need to customize the __instancecheck__ method for isinstance().
+
+        This must be performed at a metaclass level.
+        """
+
+        @classmethod
+        def __instancecheck__(mcs, obj):
+            return isinstance(obj, real_date_class)
+
+    class BaseMockedDate(real_date_class):
+        @classmethod
+        def today(cls):
+            return target
+
+    # Python2 & Python3-compatible metaclass
+    MockedDate = DateSubclassMeta('date', (BaseMockedDate,), {})
+
+    return mock.patch.object(datetime_module, 'date', MockedDate)
+
+
+def main():
+    """Run a couple of tests"""
+    target_dt = real_datetime_class(2009, 1, 1)
+    target_date = real_date_class(2009, 1, 1)
+
+    print("Entering mock")
+    with mock_datetime_now(target_dt, datetime):
+        print("- now                       ->", datetime.datetime.now())
+        print("- isinstance(now, dt)       ->", isinstance(datetime.datetime.now(), datetime.datetime))
+        print("- isinstance(target, dt)    ->", isinstance(target_dt, datetime.datetime))
+
+    with mock_date_today(target_date, datetime):
+        print("- today                     ->", datetime.date.today())
+        print("- isinstance(now, date)     ->", isinstance(datetime.date.today(), datetime.date))
+        print("- isinstance(target, date)  ->", isinstance(target_date, datetime.date))
+
+
+    print("Outside mock")
+    print("- now                       ->", datetime.datetime.now())
+    print("- isinstance(now, dt)       ->", isinstance(datetime.datetime.now(), datetime.datetime))
+    print("- isinstance(target, dt)    ->", isinstance(target_dt, datetime.datetime))
+
+    print("- today                     ->", datetime.date.today())
+    print("- isinstance(now, date)     ->", isinstance(datetime.date.today(), datetime.date))
+    print("- isinstance(target, date)  ->", isinstance(target_date, datetime.date))
+
+
+if __name__ == '__main__':
+    main()