eth2.0-specs/test_libs/pyspec/eth2spec/test/test_fork_choice.py

from eth2spec.utils.ssz.ssz_impl import signing_root

from eth2spec.test.context import with_all_phases, spec_state_test

from eth2spec.test.helpers.block import build_empty_block_for_next_slot
from eth2spec.test.helpers.attestations import get_valid_attestation
from eth2spec.test.helpers.state import next_slot


@with_all_phases
@spec_state_test
def test_basic(spec, state):
     yield 'pre', state

    # Initialization
     store = spec.get_genesis_store(state)
     blocks = []
     time = 100
     spec.on_tick(store, time)
     assert store.time == time

     # On receiving a block of `GENESIS_SLOT + 1` slot
     block = build_empty_block_for_next_slot(spec, state)
     blocks.append(block)
     spec.on_block(store, block)
     assert store.blocks[signing_root(block)] == block

     # On receiving a block of next epoch
     store.time = time + spec.SECONDS_PER_SLOT * spec.SLOTS_PER_EPOCH
     block = build_empty_block_for_next_slot(spec, state)
     block.slot += spec.SLOTS_PER_EPOCH
     blocks.append(block)

     spec.on_block(store, block)
     assert store.blocks[signing_root(block)] == block
     yield 'blocks', blocks, List[spec.BeaconBlock]

     # TODO: add tests for justified_root and finalized_root
     yield 'post', state


@with_all_phases
@spec_state_test
def test_on_attestation(spec, state):
     yield 'pre', state

     store = spec.get_genesis_store(state)
     time = 100
     spec.on_tick(store, time)

     next_slot(spec, state)

     attestation = get_valid_attestation(spec, state, slot=1)
     yield 'attestation', attestation
     indexed_attestation = spec.convert_to_indexed(state, attestation)
     spec.on_attestation(store, attestation)
     assert (
         store.latest_targets[indexed_attestation.custody_bit_0_indices[0]] ==
         spec.Target(
              epoch = attestation.data.target_epoch,
              root = attestation.data.target_root,
          )
     )

     yield 'post', state