Fix attestation, previous epoch logic and builder tools

eth2/beacon/committee_helpers.py

@@ -184,26 +184,26 @@ def get_crosslink_committees_at_slot(
         genesis_epoch=genesis_epoch,
     )
 
-    if epoch == previous_epoch:
-        committees_per_epoch = get_previous_epoch_committee_count(
+    if epoch == current_epoch:
+        committees_per_epoch = get_current_epoch_committee_count(
             state=state,
             shard_count=shard_count,
             slots_per_epoch=slots_per_epoch,
             target_committee_size=target_committee_size,
         )
-        seed = state.previous_shuffling_seed
-        shuffling_epoch = state.previous_shuffling_epoch
-        shuffling_start_shard = state.previous_shuffling_start_shard
-    elif epoch == current_epoch:
-        committees_per_epoch = get_current_epoch_committee_count(
+        seed = state.current_shuffling_seed
+        shuffling_epoch = state.current_shuffling_epoch
+        shuffling_start_shard = state.current_shuffling_start_shard
+    elif epoch == previous_epoch:
+        committees_per_epoch = get_previous_epoch_committee_count(
             state=state,
             shard_count=shard_count,
             slots_per_epoch=slots_per_epoch,
             target_committee_size=target_committee_size,
         )
-        seed = state.current_shuffling_seed
-        shuffling_epoch = state.current_shuffling_epoch
-        shuffling_start_shard = state.current_shuffling_start_shard
+        seed = state.previous_shuffling_seed
+        shuffling_epoch = state.previous_shuffling_epoch
+        shuffling_start_shard = state.previous_shuffling_start_shard
     elif epoch == next_epoch:
         current_committees_per_epoch = get_current_epoch_committee_count(
             state=state,

eth2/beacon/state_machines/forks/serenity/block_validation.py

@@ -320,7 +320,7 @@ def validate_attestation_justified_epoch(attestation_data: AttestationData,
     Validate ``justified_epoch`` field of ``attestation_data``.
     Raise ``ValidationError`` if it's invalid.
     """
-    if attestation_data.slot >= get_epoch_start_slot(current_epoch, slots_per_epoch):
+    if slot_to_epoch(attestation_data.slot + 1, slots_per_epoch) >= current_epoch:
         if attestation_data.justified_epoch != justified_epoch:
             raise ValidationError(
                 "Attestation ``slot`` is after recent epoch transition but attestation"

eth2/beacon/tools/builder/validator.py

@@ -299,18 +299,44 @@ def create_mock_signed_attestations_at_slot(
         state: BeaconState,
         config: BeaconConfig,
         attestation_slot: Slot,
+        beacon_block_root: Hash32,
         keymap: Dict[BLSPubkey, int],
         voted_attesters_ratio: float=1.0) -> Iterable[Attestation]:
     """
     Create the mocking attestations of the given ``attestation_slot`` slot with ``keymap``.
     """
+    slots_per_epoch = config.SLOTS_PER_EPOCH
+
     crosslink_committees_at_slot = get_crosslink_committees_at_slot(
+        # To avoid the epoch boundary cases
         state.copy(
             slot=state.slot + 1,
         ),
         attestation_slot,
         CommitteeConfig(config),
     )
+
+    # Get `epoch_boundary_root`
+    epoch_start_slot = get_epoch_start_slot(
+        slot_to_epoch(state.slot, slots_per_epoch),
+        slots_per_epoch,
+    )
+    if epoch_start_slot == state.slot:
+        epoch_boundary_root = beacon_block_root
+    else:
+        epoch_boundary_root = get_block_root(
+            state,
+            epoch_start_slot,
+            config.LATEST_BLOCK_ROOTS_LENGTH,
+        )
+
+    # Get `justified_block_root`
+    justified_block_root = get_block_root(
+        state,
+        get_epoch_start_slot(state.justified_epoch, slots_per_epoch),
+        config.LATEST_BLOCK_ROOTS_LENGTH,
+    )
+
     for crosslink_committee in crosslink_committees_at_slot:
         committee, shard = crosslink_committee
 
@@ -320,16 +346,12 @@ def create_mock_signed_attestations_at_slot(
         attestation_data = AttestationData(
             slot=attestation_slot,
             shard=shard,
-            beacon_block_root=ZERO_HASH32,
-            epoch_boundary_root=ZERO_HASH32,
+            beacon_block_root=beacon_block_root,
+            epoch_boundary_root=epoch_boundary_root,
             shard_block_root=ZERO_HASH32,
             latest_crosslink_root=latest_crosslink_root,
-            justified_epoch=state.previous_justified_epoch,
-            justified_block_root=get_block_root(
-                state,
-                get_epoch_start_slot(state.previous_justified_epoch, config.SLOTS_PER_EPOCH),
-                config.LATEST_BLOCK_ROOTS_LENGTH,
-            ),
+            justified_epoch=state.justified_epoch,
+            justified_block_root=justified_block_root,
         )
 
         yield create_mock_signed_attestation(

eth2/beacon/types/states.py

@@ -295,11 +295,7 @@ def current_epoch(self, slots_per_epoch: int) -> Epoch:
         return slot_to_epoch(self.slot, slots_per_epoch)
 
     def previous_epoch(self, slots_per_epoch: int, genesis_epoch: int) -> Epoch:
-        current_epoch: Epoch = self.current_epoch(slots_per_epoch)
-        if current_epoch == genesis_epoch:
-            return current_epoch
-        else:
-            return Epoch(current_epoch - 1)
+        return Epoch(max(self.current_epoch(slots_per_epoch) - 1, genesis_epoch))
 
     def next_epoch(self, slots_per_epoch: int) -> Epoch:
         return Epoch(self.current_epoch(slots_per_epoch) + 1)

tests/eth2/beacon/conftest.py

@@ -8,7 +8,6 @@
 )
 
 import eth2._utils.bls as bls
-from eth2.beacon._utils.hash import hash_eth2
 from eth2.beacon.configs import (
     BeaconConfig,
     CommitteeConfig,
@@ -54,7 +53,13 @@
 
 @pytest.fixture(scope="session")
 def privkeys():
-    return [int.from_bytes(hash_eth2(str(i).encode('utf-8'))[:4], 'big') for i in range(100)]
+    """
+    Rationales:
+    1. Making the privkeys be small integers to make multiplying easier for tests.
+    2. Using ``2**i`` instead of ``i``:
+        The combinations of validators would not lead to unique pubkeys.
+    """
+    return [2 ** i for i in range(100)]
 
 
 @pytest.fixture(scope="session")

tests/eth2/beacon/state_machines/forks/test_serenity_block_attestation_validation.py

@@ -90,13 +90,12 @@ def test_validate_attestation_slot(sample_attestation_data_params,
         'is_valid,'
     ),
     [
-        (13, 1, 2, 0, 1, 5, True),
-        (13, 0, 2, 0, 1, 5, False),  # targeting previous_justified_epoch, should be targeting justified_epoch # noqa: E501
-        (13, 4, 2, 0, 1, 5, False),  # targeting future epoch, should be targeting justified_epoch
-        (29, 1, 3, 1, 2, 10, True),
-        (29, 2, 3, 1, 2, 10, False),  # targeting justified_epoch, should be targeting previous_justified_epoch # noqa: E501
-        (29, 3, 3, 1, 2, 10, False),  # targeting future epoch, should be targeting previous_justified_epoch # noqa: E501
-        (10, 1, 1, 1, 1, 10, True),
+        # slot_to_epoch(attestation_data.slot + 1, slots_per_epoch) >= current_epoch
+        (23, 2, 3, 1, 2, 8, True),  # attestation_data.justified_epoch == justified_epoch
+        (23, 1, 3, 1, 2, 8, False),  # attestation_data.justified_epoch != justified_epoch
+        # slot_to_epoch(attestation_data.slot + 1, slots_per_epoch) < current_epoch
+        (22, 1, 3, 1, 2, 8, True),  # attestation_data.justified_epoch == previous_justified_epoch
+        (22, 2, 3, 1, 2, 8, False),  # attestation_data.justified_epoch != previous_justified_epoch
     ]
 )
 def test_validate_attestation_justified_epoch(
@@ -114,6 +113,7 @@ def test_validate_attestation_justified_epoch(
     )
 
     if is_valid:
+        # slot_to_epoch(attestation_data.slot + 1, slots_per_epoch) >= current_epoch
         validate_attestation_justified_epoch(
             attestation_data,
             current_epoch,

tests/eth2/beacon/state_machines/forks/test_serenity_operation_processing.py

@@ -21,6 +21,7 @@
 
 
 def test_process_max_attestations(genesis_state,
+                                  genesis_block,
                                   sample_beacon_block_params,
                                   sample_beacon_block_body_params,
                                   config,
@@ -32,11 +33,12 @@ def test_process_max_attestations(genesis_state,
     )
 
     attestations = create_mock_signed_attestations_at_slot(
-        state,
-        config,
-        attestation_slot,
-        keymap,
-        1.0,
+        state=state,
+        config=config,
+        attestation_slot=attestation_slot,
+        beacon_block_root=genesis_block.root,
+        keymap=keymap,
+        voted_attesters_ratio=1.0,
     )
 
     attestations_count = len(attestations)
@@ -140,6 +142,7 @@ def test_process_proposer_slashings(genesis_state,
     ]
 )
 def test_process_attestations(genesis_state,
+                              genesis_block,
                               sample_beacon_block_params,
                               sample_beacon_block_body_params,
                               config,
@@ -153,11 +156,12 @@ def test_process_attestations(genesis_state,
     )
 
     attestations = create_mock_signed_attestations_at_slot(
-        state,
-        config,
-        attestation_slot,
-        keymap,
-        1.0,
+        state=state,
+        config=config,
+        attestation_slot=attestation_slot,
+        beacon_block_root=genesis_block.root,
+        keymap=keymap,
+        voted_attesters_ratio=1.0,
     )
 
     assert len(attestations) > 0

tests/eth2/beacon/state_machines/test_demo.py

@@ -24,7 +24,7 @@
         'shard_count'
     ),
     [
-        (20, 4, 2, 2, 2)
+        (40, 8, 2, 3, 2)
     ]
 )
 def test_demo(base_db,
@@ -49,12 +49,17 @@ def test_demo(base_db,
     state = genesis_state
     block = genesis_block
 
-    current_slot = 1
     chain_length = 3 * config.SLOTS_PER_EPOCH
-    attestations = ()
     blocks = (block,)
-    for current_slot in range(chain_length):
-        # two epochs
+
+    attestations_map = {}  # Dict[Slot, Sequence[Attestation]]
+
+    for current_slot in range(1, chain_length):
+        if current_slot > config.MIN_ATTESTATION_INCLUSION_DELAY:
+            attestations = attestations_map[current_slot - config.MIN_ATTESTATION_INCLUSION_DELAY]
+        else:
+            attestations = ()
+
         block = create_mock_block(
             state=state,
             config=config,
@@ -85,17 +90,22 @@ def test_demo(base_db,
         chaindb.persist_block(block, SerenityBeaconBlock)
 
         blocks += (block,)
-        if current_slot > config.MIN_ATTESTATION_INCLUSION_DELAY:
-            attestation_slot = current_slot - config.MIN_ATTESTATION_INCLUSION_DELAY
-            attestations = create_mock_signed_attestations_at_slot(
-                state,
-                config,
-                attestation_slot,
-                keymap,
-                1.0,
-            )
-        else:
-            attestations = ()
+
+        # Mock attestations
+        attestation_slot = current_slot
+        attestations = create_mock_signed_attestations_at_slot(
+            state=state,
+            config=config,
+            attestation_slot=attestation_slot,
+            beacon_block_root=block.root,
+            keymap=keymap,
+            voted_attesters_ratio=1.0,
+        )
+        attestations_map[attestation_slot] = attestations
 
     assert state.slot == chain_length - 1
     assert isinstance(sm.block, SerenityBeaconBlock)
+
+    # Justification assertions
+    assert state.justified_epoch == 2
+    assert state.finalized_epoch == 1

tests/eth2/beacon/test_committee_helpers.py

@@ -386,10 +386,10 @@ def mock_generate_seed(state,
     previous_epoch = state.previous_epoch(slots_per_epoch, genesis_epoch)
     next_epoch = current_epoch + 1
 
-    if epoch == previous_epoch:
-        seed = state.previous_shuffling_seed
-    elif epoch == current_epoch:
+    if epoch == current_epoch:
         seed = state.current_shuffling_seed
+    elif epoch == previous_epoch:
+        seed = state.previous_shuffling_seed
     elif epoch == next_epoch:
         if registry_change or should_reseed:
             seed = new_seed