def test_pop_halves_array_capacity_if_less_than_quarter_of_capacity_used(
self):
da = DynamicArray()
da._capacity = 64
da._n = 17
da._A = da._make_array(da._capacity)
da._A[0:17] = [None] * 17
# first pop() should not shrink the array, since with 16 elements
# we have not passed the N/4 threshold.
da.pop()
self.assertEqual(da._capacity, 64)
# second pop() should trigger halving the array capacity:
da.pop()
self.assertEqual(da._capacity, 32)
def test_pop_removes_and_returns_last_element_of_array(self):
da = DynamicArray()
da._n = 3
da._capacity = 3
da._A = da._make_array(da._capacity)
da._A[0:3] = ['foo', 'bar', 'baz']
result = da.pop()
self.assertEqual(result, 'baz')
self.assertEqual(da._A[0:2], ['foo', 'bar'])
self.assertEqual(da._n, 2)