Add `process_light_client_update` tests

configs/mainnet/lightclient_patch.yaml

@@ -29,3 +29,9 @@ EPOCHS_PER_SYNC_COMMITTEE_PERIOD: 256
 # Signature domains
 # ---------------------------------------------------------------
 DOMAIN_SYNC_COMMITTEE: 0x07000000
+
+
+# Sync protocol
+# ---------------------------------------------------------------
+# 2**13 (=8192)
+LIGHT_CLIENT_UPDATE_TIMEOUT: 8192

configs/minimal/lightclient_patch.yaml

@@ -29,3 +29,9 @@ EPOCHS_PER_SYNC_COMMITTEE_PERIOD: 8
 # Signature domains
 # ---------------------------------------------------------------
 DOMAIN_SYNC_COMMITTEE: 0x07000000
+
+
+# Sync protocol
+# ---------------------------------------------------------------
+# [customized]
+LIGHT_CLIENT_UPDATE_TIMEOUT: 32

tests/core/pyspec/eth2spec/test/helpers/sync_committee.py

@@ -5,8 +5,9 @@ from eth2spec.test.helpers.block import (
 from eth2spec.utils import bls
 
 
-def compute_sync_committee_signature(spec, state, slot, privkey):
+def compute_sync_committee_signature(spec, state, slot, privkey, block_root=None):
     domain = spec.get_domain(state, spec.DOMAIN_SYNC_COMMITTEE, spec.compute_epoch_at_slot(slot))
+    if block_root is None:
         if slot == state.slot:
             block_root = build_empty_block_for_next_slot(spec, state).parent_root
         else:
@@ -15,7 +16,7 @@ def compute_sync_committee_signature(spec, state, slot, privkey):
     return bls.Sign(privkey, signing_root)
 
 
-def compute_aggregate_sync_committee_signature(spec, state, slot, participants):
+def compute_aggregate_sync_committee_signature(spec, state, slot, participants, block_root=None):
     if len(participants) == 0:
         return spec.G2_POINT_AT_INFINITY
 
@@ -28,6 +29,7 @@ def compute_aggregate_sync_committee_signature(spec, state, slot, participants):
                 state,
                 slot,
                 privkey,
+                block_root=block_root,
             )
         )
     return bls.Aggregate(signatures)

tests/core/pyspec/eth2spec/test/lightclient_patch/unittests/test_helpers.py

@@ -9,7 +9,7 @@ from eth2spec.test.helpers.merkle import build_proof
 @with_phases([LIGHTCLIENT_PATCH])
 @spec_state_test
 def test_next_sync_committee_tree(spec, state):
-    state.next_sync_committee = spec.SyncCommittee(
+    state.next_sync_committee: object = spec.SyncCommittee(
         pubkeys=[state.validators[i]for i in range(spec.SYNC_COMMITTEE_SIZE)]
     )
     next_sync_committee_branch = build_proof(state.get_backing(), spec.NEXT_SYNC_COMMITTEE_INDEX)

tests/core/pyspec/eth2spec/test/lightclient_patch/unittests/test_sync_protocol.py

@@ -0,0 +1,212 @@
+from eth2spec.test.context import (
+    LIGHTCLIENT_PATCH,
+    spec_state_test,
+    with_phases,
+)
+from eth2spec.test.helpers.attestations import next_epoch_with_attestations
+from eth2spec.test.helpers.block import (
+    build_empty_block,
+    build_empty_block_for_next_slot,
+)
+from eth2spec.test.helpers.state import (
+    next_slots,
+    state_transition_and_sign_block,
+)
+from eth2spec.test.helpers.sync_committee import (
+    compute_aggregate_sync_committee_signature,
+)
+from eth2spec.test.helpers.merkle import build_proof
+
+
+@with_phases([LIGHTCLIENT_PATCH])
+@spec_state_test
+def test_process_light_client_update_not_updated(spec, state):
+    pre_snapshot = spec.LightClientSnapshot(
+        header=spec.BeaconBlockHeader(),
+        current_sync_committee=state.current_sync_committee,
+        next_sync_committee=state.next_sync_committee,
+    )
+    store = spec.LightClientStore(
+        snapshot=pre_snapshot,
+        valid_updates=[]
+    )
+
+    # Block at slot 1 doesn't increase sync committee period, so it won't update snapshot
+    block = build_empty_block_for_next_slot(spec, state)
+    signed_block = state_transition_and_sign_block(spec, state, block)
+    block_header = spec.BeaconBlockHeader(
+        slot=signed_block.message.slot,
+        proposer_index=signed_block.message.proposer_index,
+        parent_root=signed_block.message.parent_root,
+        state_root=signed_block.message.state_root,
+        body_root=signed_block.message.body.hash_tree_root(),
+    )
+    # Sync committee signing the header
+    committee = spec.get_sync_committee_indices(state, spec.get_current_epoch(state))
+    sync_committee_bits = [True] * len(committee)
+    sync_committee_signature = compute_aggregate_sync_committee_signature(
+        spec,
+        state,
+        block.slot,
+        committee,
+    )
+    next_sync_committee_branch = [spec.Bytes32() for _ in range(spec.floorlog2(spec.NEXT_SYNC_COMMITTEE_INDEX))]
+
+    # Ensure that finality checkpoint is genesis
+    assert state.finalized_checkpoint.epoch == 0
+    # Finality is unchanged
+    finality_header = spec.BeaconBlockHeader()
+    finality_branch = [spec.Bytes32() for _ in range(spec.floorlog2(spec.FINALIZED_ROOT_INDEX))]
+
+    update = spec.LightClientUpdate(
+        header=block_header,
+        next_sync_committee=state.next_sync_committee,
+        next_sync_committee_branch=next_sync_committee_branch,
+        finality_header=finality_header,
+        finality_branch=finality_branch,
+        sync_committee_bits=sync_committee_bits,
+        sync_committee_signature=sync_committee_signature,
+        fork_version=state.fork.current_version,
+    )
+
+    spec.process_light_client_update(store, update, state.slot, state.genesis_validators_root)
+
+    assert len(store.valid_updates) == 1
+    assert store.valid_updates[0] == update
+    assert store.snapshot == pre_snapshot
+
+
+@with_phases([LIGHTCLIENT_PATCH])
+@spec_state_test
+def test_process_light_client_update_timeout(spec, state):
+    pre_snapshot = spec.LightClientSnapshot(
+        header=spec.BeaconBlockHeader(),
+        current_sync_committee=state.current_sync_committee,
+        next_sync_committee=state.next_sync_committee,
+    )
+    store = spec.LightClientStore(
+        snapshot=pre_snapshot,
+        valid_updates=[]
+    )
+
+    # Forward to next sync committee period
+    next_slots(spec, state, spec.SLOTS_PER_EPOCH * (spec.EPOCHS_PER_SYNC_COMMITTEE_PERIOD))
+    snapshot_period = spec.compute_epoch_at_slot(pre_snapshot.header.slot) // spec.EPOCHS_PER_SYNC_COMMITTEE_PERIOD
+    update_period = spec.compute_epoch_at_slot(state.slot) // spec.EPOCHS_PER_SYNC_COMMITTEE_PERIOD
+    assert snapshot_period + 1 == update_period
+
+    block = build_empty_block_for_next_slot(spec, state)
+    signed_block = state_transition_and_sign_block(spec, state, block)
+    block_header = spec.BeaconBlockHeader(
+        slot=signed_block.message.slot,
+        proposer_index=signed_block.message.proposer_index,
+        parent_root=signed_block.message.parent_root,
+        state_root=signed_block.message.state_root,
+        body_root=signed_block.message.body.hash_tree_root(),
+    )
+
+    # Sync committee is updated
+    next_sync_committee_branch = build_proof(state.get_backing(), spec.NEXT_SYNC_COMMITTEE_INDEX)
+    # Finality is unchanged
+    finality_header = spec.BeaconBlockHeader()
+    finality_branch = [spec.Bytes32() for _ in range(spec.floorlog2(spec.FINALIZED_ROOT_INDEX))]
+
+    # Sync committee signing the finalized_block_header
+    committee = spec.get_sync_committee_indices(state, spec.get_current_epoch(state))
+    sync_committee_bits = [True] * len(committee)
+    sync_committee_signature = compute_aggregate_sync_committee_signature(
+        spec,
+        state,
+        block_header.slot,
+        committee,
+        block_root=spec.Root(block_header.hash_tree_root()),
+    )
+
+    update = spec.LightClientUpdate(
+        header=block_header,
+        next_sync_committee=state.next_sync_committee,
+        next_sync_committee_branch=next_sync_committee_branch,
+        finality_header=finality_header,
+        finality_branch=finality_branch,
+        sync_committee_bits=sync_committee_bits,
+        sync_committee_signature=sync_committee_signature,
+        fork_version=state.fork.current_version,
+    )
+
+    spec.process_light_client_update(store, update, state.slot, state.genesis_validators_root)
+
+    # snapshot has been updated
+    assert len(store.valid_updates) == 0
+    assert store.snapshot.header == update.header
+
+
+@with_phases([LIGHTCLIENT_PATCH])
+@spec_state_test
+def test_process_light_client_update_finality_updated(spec, state):
+    pre_snapshot = spec.LightClientSnapshot(
+        header=spec.BeaconBlockHeader(),
+        current_sync_committee=state.current_sync_committee,
+        next_sync_committee=state.next_sync_committee,
+    )
+    store = spec.LightClientStore(
+        snapshot=pre_snapshot,
+        valid_updates=[]
+    )
+
+    # Change finality
+    blocks = []
+    next_slots(spec, state, spec.SLOTS_PER_EPOCH * 2)
+    for epoch in range(3):
+        prev_state, new_blocks, state = next_epoch_with_attestations(spec, state, True, True)
+        blocks += new_blocks
+    # Ensure that finality checkpoint has changed
+    assert state.finalized_checkpoint.epoch == 3
+    # Ensure that it's same period
+    snapshot_period = spec.compute_epoch_at_slot(pre_snapshot.header.slot) // spec.EPOCHS_PER_SYNC_COMMITTEE_PERIOD
+    update_period = spec.compute_epoch_at_slot(state.slot) // spec.EPOCHS_PER_SYNC_COMMITTEE_PERIOD
+    assert snapshot_period == update_period
+
+    # Updated sync_committee and finality
+    next_sync_committee_branch = [spec.Bytes32() for _ in range(spec.floorlog2(spec.NEXT_SYNC_COMMITTEE_INDEX))]
+    finalized_block_header = blocks[spec.SLOTS_PER_EPOCH - 1].message
+    assert finalized_block_header.slot == spec.compute_start_slot_at_epoch(state.finalized_checkpoint.epoch)
+    assert finalized_block_header.hash_tree_root() == state.finalized_checkpoint.root
+    finality_branch = build_proof(state.get_backing(), spec.FINALIZED_ROOT_INDEX)
+
+    # Sync committee signing the finalized_block_header
+    committee = spec.get_sync_committee_indices(state, spec.get_current_epoch(state))
+    sync_committee_bits = [True] * len(committee)
+    sync_committee_signature = compute_aggregate_sync_committee_signature(
+        spec,
+        state,
+        finalized_block_header.slot,
+        committee,
+        block_root=spec.Root(finalized_block_header.hash_tree_root()),
+    )
+
+    # Build block header
+    block = build_empty_block(spec, state)
+    block_header = spec.BeaconBlockHeader(
+        slot=block.slot,
+        proposer_index=block.proposer_index,
+        parent_root=block.parent_root,
+        state_root=state.hash_tree_root(),
+        body_root=block.body.hash_tree_root(),
+    )
+
+    update = spec.LightClientUpdate(
+        header=finalized_block_header,
+        next_sync_committee=state.next_sync_committee,
+        next_sync_committee_branch=next_sync_committee_branch,
+        finality_header=block_header,
+        finality_branch=finality_branch,
+        sync_committee_bits=sync_committee_bits,
+        sync_committee_signature=sync_committee_signature,
+        fork_version=state.fork.current_version,
+    )
+
+    spec.process_light_client_update(store, update, state.slot, state.genesis_validators_root)
+
+    # snapshot has been updated
+    assert len(store.valid_updates) == 0
+    assert store.snapshot.header == update.header