def METHOD_NAME(self):
    eq = self.assertEqual
    # First try strict
    eq(self.db.guess_type('foo.xul', strict=True), (None, None))
    eq(self.db.guess_extension('image/jpg', strict=True), None)
    # And then non-strict
    eq(self.db.guess_type('foo.xul', strict=False), ('text/xul', None))
    eq(self.db.guess_extension('image/jpg', strict=False), '.jpg')