def test_imbalance_penalty():
r""" Test an imbalance penalty by moving back and forth
The imbalance fee looks like
20 | /
| /
10 |\. /
| \. /
0 | \/
---------------
0 50 100
For each input, we first assume the channel is used to forward tokens to a
payee, which moves the capacity from x1 to x2. The we assume the same
amount is mediated in the opposite direction (moving from x2 to x1) and
check that the calculated fee is the same as before just with the opposite
sign.
"""
v_schedule = FeeScheduleState(imbalance_penalty=[
(TokenAmount(0), FeeAmount(10)),
(TokenAmount(50), FeeAmount(0)),
(TokenAmount(100), FeeAmount(20)),
])
for x1, amount, expected_fee_payee, expected_fee_payer in [
(0, 50, -6, 10),
(50, 50, 12, -20),
(0, 10, -2, 2),
(10, 10, -2, 2),
(0, 20, -5, 4),
(40, 15, 0, 0),
]:
x2 = x1 + amount
assert v_schedule.fee_payee(
balance=Balance(100 - x1), amount=PaymentWithFeeAmount(
amount)) == FeeAmount(expected_fee_payee)
assert v_schedule.fee_payer(
balance=Balance(100 - x2), amount=PaymentWithFeeAmount(
amount)) == FeeAmount(expected_fee_payer)
with pytest.raises(UndefinedMediationFee):
v_schedule.fee_payee(balance=Balance(0),
amount=PaymentWithFeeAmount(1))
with pytest.raises(UndefinedMediationFee):
v_schedule.fee_payer(balance=Balance(100),
amount=PaymentWithFeeAmount(1))
def test_basic_fee():
flat_schedule = FeeScheduleState(flat=FeeAmount(2))
assert flat_schedule.fee_payer(PaymentWithFeeAmount(10),
balance=Balance(0)) == FeeAmount(2)
prop_schedule = FeeScheduleState(
proportional=ProportionalFeeAmount(int(0.01e6)))
assert prop_schedule.fee_payer(PaymentWithFeeAmount(40),
balance=Balance(0)) == FeeAmount(0)
assert prop_schedule.fee_payer(PaymentWithFeeAmount(60),
balance=Balance(0)) == FeeAmount(1)
assert prop_schedule.fee_payer(PaymentWithFeeAmount(1000),
balance=Balance(0)) == FeeAmount(10)
combined_schedule = FeeScheduleState(flat=FeeAmount(2),
proportional=ProportionalFeeAmount(
int(0.01e6)))
assert combined_schedule.fee_payer(PaymentWithFeeAmount(60),
balance=Balance(0)) == FeeAmount(3)