Add tests.alter_time and fix time altering on pypy.

2 files changed, 121 insertions, 40 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()
diff --git a/tests/utils.py b/tests/utils.py
index 823e82b..0111df3 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -23,50 +23,23 @@
 import datetime
 
 from .compat import mock
+from . import alter_time
 
 
 class MultiModulePatcher(object):
     """An abstract context processor for patching multiple modules."""
 
-    replaced_symbol = None
-    replaced_symbol_module = None
-    module_imported_as = ''
-
     def __init__(self, *target_modules, **kwargs):
         super(MultiModulePatcher, self).__init__(**kwargs)
-        if not self.module_imported_as:
-            self.module_imported_as = replaced_symbol.__module__.__name__
         self.patchers = [self._build_patcher(mod) for mod in target_modules]
 
-    def _check_module(self, target_module):
-        if not self.replaced_symbol_module:
-            # No check to perform
-            return
-
-        replaced_import = getattr(target_module, self.module_imported_as)
-        assert replaced_import is self.replaced_symbol_module, (
-            "Cannot patch import %s.%s (%r != %r)" % (
-                target_module.__name__, self.module_imported_as,
-                replaced_import, self.replaced_symbol_module))
-
     def _build_patcher(self, target_module):
         """Build a mock patcher for the target module."""
-        self._check_module(target_module)
-
-        return mock.patch.object(
-            getattr(target_module, self.module_imported_as),
-            self.replaced_symbol.__name__,
-            mock.Mock(wraps=self.replaced_symbol),
-        )
-
-    def setup_mocked_symbol(self, mocked_symbol):
-        """Setup a mocked symbol for later use."""
-        pass
+        raise NotImplementedError()
 
     def __enter__(self):
         for patcher in self.patchers:
             mocked_symbol = patcher.start()
-            self.setup_mocked_symbol(mocked_symbol)
 
     def __exit__(self, exc_type=None, exc_val=None, exc_tb=None):
         for patcher in self.patchers:
@@ -75,26 +48,21 @@ class MultiModulePatcher(object):
 
 class mocked_date_today(MultiModulePatcher):
     """A context processor changing the value of date.today()."""
-    replaced_symbol = datetime.date
-    replaced_symbol_module = datetime
-    module_imported_as = 'datetime'
 
     def __init__(self, target_date, *target_modules, **kwargs):
         self.target_date = target_date
         super(mocked_date_today, self).__init__(*target_modules, **kwargs)
 
-    def setup_mocked_symbol(self, mocked_date):
-        mocked_date.today.return_value = self.target_date
+    def _build_patcher(self, target_module):
+        module_datetime = getattr(target_module, 'datetime')
+        return alter_time.mock_date_today(self.target_date, module_datetime)
 
 
 class mocked_datetime_now(MultiModulePatcher):
-    replaced_symbol = datetime.datetime
-    replaced_symbol_module = datetime
-    module_imported_as = 'datetime'
-
     def __init__(self, target_dt, *target_modules, **kwargs):
         self.target_dt = target_dt
         super(mocked_datetime_now, self).__init__(*target_modules, **kwargs)
 
-    def setup_mocked_symbol(self, mocked_datetime):
-        mocked_datetime.now.return_value = self.target_dt
+    def _build_patcher(self, target_module):
+        module_datetime = getattr(target_module, 'datetime')
+        return alter_time.mock_datetime_now(self.target_dt, module_datetime)