def test_value_accumulator_can_add_value():
value = 4.2
acc = ValueAccumulator()
acc.add(value)
assert acc.count == 1
assert acc.sum == value
assert acc.avg == value
assert acc.stddev is None
assert acc.min == value
assert acc.max == value
def test_value_accumulator_can_add_several_values():
values = [4.2, -1.3, 10.8]
acc = ValueAccumulator()
for value in values:
acc.add(value)
assert acc.count == len(values)
assert acc.sum == sum(values)
assert acc.avg == statistics.mean(values)
assert acc.stddev == statistics.stdev(values)
assert acc.min == min(values)
assert acc.max == max(values)
def test_value_accumulator_handles_same_values():
value = 4.2
count = 5
acc = ValueAccumulator()
for _ in range(count):
acc.add(value)
assert acc.count == count
assert acc.sum == value * count
assert acc.avg == value
assert acc.stddev == 0
assert acc.min == value
assert acc.max == value
def test_value_accumulator_eq_has_value_semantics():
a = ValueAccumulator()
b = ValueAccumulator()
assert a == b
a.add(1.0)
assert a != b
b.add(1.0)
assert a == b
a.add(2.0)
b.add(3.0)
assert a != b
def _value_accumulator(values):
acc = ValueAccumulator()
for v in values:
acc.add(v)
return acc