def test_when_run_where_then_enumerate_only_after_to_list(self):
sequence = []
def less_than_5(x):
w = x < 5
sequence.append(5)
return w
enumerable = Enumerable(generate).where(less_than_5).where(less_than_5)
self.assertTrue(len(sequence) == 0)
enumerable.to_list()
self.assertTrue(len(sequence) > 0)
def test_when_run_to_list_several_times_then_enumerate_only_once(self):
sequence = []
def less_than_5(x):
w = x < 5
sequence.append(5)
return w
enumerable = Enumerable(generate).where(less_than_5)
enumerable.to_list()
counter = len(sequence)
enumerable.to_list()
self.assertEqual(counter, len(sequence))
def test_when_sort_descending_then_return_values_sorted_descending(self):
a = Dummy(1, 8)
b = Dummy(2, 6)
c = Dummy(3, 4)
d = Dummy(4, 2)
dummies = [a, b, c, d]
values = Enumerable(dummies).sort(lambda x: x.B, descending=True)
self.assertSequenceEqual(values.to_list(), [a, b, c, d])