nomos-specs/cryptarchia/test_leader.py

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from unittest import TestCase
import numpy as np
from .cryptarchia import (
Leader,
Config,
EpochState,
LedgerState,
Coin,
phi,
TimeConfig,
Slot,
)
from .test_common import mk_config
class TestLeader(TestCase):
def test_slot_leader_statistics(self):
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epoch = EpochState(
stake_distribution_snapshot=LedgerState(),
nonce_snapshot=LedgerState(nonce=b"1010101010"),
inferred_total_active_stake=1000,
)
coin = Coin(sk=0, value=10)
f = 0.05
l = Leader(
config=mk_config([coin]).replace(active_slot_coeff=f),
coin=coin,
)
# We'll use the Margin of Error equation to decide how many samples we need.
# https://en.wikipedia.org/wiki/Margin_of_error
margin_of_error = 1e-4
p = phi(f=f, alpha=10 / epoch.total_active_stake())
std = np.sqrt(p * (1 - p))
Z = 3 # we want 3 std from the mean to be within the margin of error
N = int((Z * std / margin_of_error) ** 2)
# After N slots, the measured leader rate should be within the
# interval `p +- margin_of_error` with high probabiltiy
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leader_rate = (
sum(
l.try_prove_slot_leader(epoch, Slot(slot), bytes(32)) is not None
for slot in range(N)
)
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/ N
)
assert (
abs(leader_rate - p) < margin_of_error
), f"{leader_rate} != {p}, err={abs(leader_rate - p)} > {margin_of_error}"