def chaindb_at_genesis(base_db, genesis_state, genesis_block,
fork_choice_scoring):
return BeaconChainDB.from_genesis(base_db, genesis_state,
SerenitySignedBeaconBlock,
fork_choice_scoring)
def test_demo(base_db, validator_count, keymap, pubkeys, fork_choice_scoring):
bls.use_noop_backend()
config = MINIMAL_SERENITY_CONFIG
override_lengths(config)
genesis_slot = GENESIS_SLOT
genesis_epoch = GENESIS_EPOCH
genesis_state, genesis_block = create_mock_genesis(
pubkeys=pubkeys[:validator_count],
config=config,
keymap=keymap,
genesis_block_class=SerenityBeaconBlock,
)
chaindb = BeaconChainDB.from_genesis(
base_db, genesis_state, SerenitySignedBeaconBlock, fork_choice_scoring
)
fixture_sm = SkeletonLakeStateMachine(chaindb)
for i in range(validator_count):
assert genesis_state.validators[i].is_active(genesis_slot)
state = genesis_state
block = SerenitySignedBeaconBlock.create(message=genesis_block)
chain_length = 4 * config.SLOTS_PER_EPOCH
blocks = (block,)
attestations_map = {} # Dict[Slot, Sequence[Attestation]]
for current_slot in range(genesis_slot + 1, genesis_slot + chain_length + 1):
if current_slot > genesis_slot + config.MIN_ATTESTATION_INCLUSION_DELAY:
attestations = attestations_map[
current_slot - config.MIN_ATTESTATION_INCLUSION_DELAY
]
else:
attestations = ()
future_state, _ = fixture_sm.apply_state_transition(
state, future_slot=current_slot
)
proposer_index = get_beacon_proposer_index(future_state, config)
proposer_pubkey = state.validators[proposer_index].pubkey
private_key = keymap[proposer_pubkey]
randao_reveal = generate_randao_reveal(private_key, current_slot, state, config)
block_proposal = create_block_proposal(
current_slot,
block.message.hash_tree_root,
randao_reveal,
state.eth1_data,
attestations,
state,
fixture_sm,
)
block = sign_block(state, block_proposal, private_key, config.SLOTS_PER_EPOCH)
state, block = fixture_sm.apply_state_transition(state, block)
chaindb.persist_state(state)
chaindb.persist_block(block, SerenitySignedBeaconBlock, fork_choice_scoring)
blocks += (block,)
# Mock attestations
attestation_slot = current_slot
attestations = create_mock_signed_attestations_at_slot(
state=state,
config=config,
state_machine=fixture_sm,
attestation_slot=attestation_slot,
beacon_block_root=block.message.hash_tree_root,
keymap=keymap,
voted_attesters_ratio=1.0,
)
attestations_map[attestation_slot] = attestations
assert state.slot == chain_length + genesis_slot
# Justification assertions
# NOTE: why are the number `2` or `3` used in the checks below?
# Answer:
# "We do not check any justification and finality during epochs 0 or 1. We do check for
# justification and finality from epoch 2 onward."
# [epoch 0]------[epoch 1]------>
#
# "In epoch 2, we justify the current epoch. This epoch is in fact justified but we do not
# recognize it in the protocol due to an artifact of the construction of the genesis state
# (using the `zero` value for `Checkpoint` type)."
# [epoch 0]------[epoch 1]------[epoch 2]*------>
# []*: checkpoint justified
# []**: checkpoint finalized
#
# "In epoch 3, we have the previous justified checkpoint at the prior current justified
# checkpoint (so `GENESIS_EPOCH + 2`) and we justify this current epoch. we check finality here
# and see that we finalize the prior justified checkpoint at epoch 2."
# [epoch 0]------[epoch 1]------[epoch 2]**------[epoch 3]*------>
#
# "Given the way we handle epoch processing (i.e. process a given epoch at the start of
# the next epoch), we need to transition through `4 * SLOTS_PER_EPOCH` worth of slots to
# include the processing of epoch 3."
#
# source: https://github.com/ethereum/trinity/pull/1214#issuecomment-546184080
#
# epoch | prev_justified_checkpoint | cur_justified_checkpoint | finalized_checkpoint
# ------|---------------------------|--------------------------|---------------------
# 0 | 0 | 0 | 0
# 1 | 0 | 0 | 0
# 2 | 0 | 0 | 0
# 3 | 0 | 2 | 0
# 4 | 2 | 3 | 2
assert state.previous_justified_checkpoint.epoch == 2 + genesis_epoch
assert state.current_justified_checkpoint.epoch == 3 + genesis_epoch
assert state.finalized_checkpoint.epoch == 2 + genesis_epoch