Tim Chase wrote:
> Are there best practices for testing dates that are properties
> which take the current date into consideration? I have something
> like
>
> class Foo:
> def _get_year_range(self):
> return (self._min_year, self._max_year)
> def _set_year_range(self, year):
> if isinstance(year, tuple):
> _min, _max = map(window_date, year)
> if _min > _max: _min, _max = _max, _min
> else: # a raw int
> _min = _max = window_date(year)
> self._min_year, self._max_year = _min, _max
> year_range = property(
> fget=_get_year_range,
> fget=_get_year_range,
> )
>
> The problem is that the behavior of the window_date function
> depends on the current date (the function makes a guess about
> adding the century if the year was <100). It *does* take an
> "around" parameter that defaults to the current date. So for
> pure testing of the window_date() function, I can hard-code some
> date where I know what the expected values should be.
>
> However if I want to write a test-harness for my property, I have
> no way (AFAIK) to pass in this fixed date to _set_year_range() so
> that the success/failure of my tests doesn't depend on the day I
> run them:
>
> class TestFoo:
> def test_year_range(self):
> around = date(2011,1,1)
> f = Foo()
> f.year_range = (97, 84)
> self.assertEqual(f.year_range, (1984, 1997))
>
> Any suggestions/tips/hints? Thanks,
Temporarily replace the window_date() function with something that you can
control completely. Assuming Foo and window_date are defined in foo.py:
# untested
import foo
class TestFoo:
def setUp(self):
foo.window_date = functools.partial(foo.window_date,
around=date(2011, 1, 1))
def tearDown(self):
foo.window_date = foo.window_date.func
def test_year_range(self):
f = Foo()
f.year_range = (97, 84)
self.assertEqual(f.year_range, (1984, 1997))
See also http://www.voidspace.org.uk/python/mock/
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