v0.11 multiple blocks in single slot patch

specs/phase0/beacon-chain.md

@@ -1219,7 +1219,7 @@ def verify_block_signature(state: BeaconState, signed_block: SignedBeaconBlock)
 
 ```python
 def process_slots(state: BeaconState, slot: Slot) -> None:
-    assert state.slot <= slot
+    assert state.slot < slot
     while state.slot < slot:
         process_slot(state)
         # Process epoch on the start slot of the next epoch
@@ -1494,6 +1494,8 @@ def process_block(state: BeaconState, block: BeaconBlock) -> None:
 def process_block_header(state: BeaconState, block: BeaconBlock) -> None:
     # Verify that the slots match
     assert block.slot == state.slot
+    # Verify that the block is newer than latest block header
+    assert block.slot > state.latest_block_header.slot
     # Verify that proposer index is the correct index
     assert block.proposer_index == get_beacon_proposer_index(state)
     # Verify that the parent matches

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

@@ -243,7 +243,8 @@ def fill_aggregate_attestation(spec, state, attestation, signed=False):
 
 
 def add_attestations_to_state(spec, state, attestations, slot):
-    spec.process_slots(state, slot)
+    if state.slot < slot:
+        spec.process_slots(state, slot)
     for attestation in attestations:
         spec.process_attestation(state, attestation)
 

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

@@ -15,7 +15,8 @@ def get_proposer_index_maybe(spec, state, slot, proposer_index=None):
                       " Signing block is slow due to transition for proposer index calculation.")
             # use stub state to get proposer index of future slot
             stub_state = state.copy()
-            spec.process_slots(stub_state, slot)
+            if stub_state.slot < slot:
+                spec.process_slots(stub_state, slot)
             proposer_index = spec.get_beacon_proposer_index(stub_state)
     return proposer_index
 
@@ -52,15 +53,19 @@ def sign_block(spec, state, block, proposer_index=None):
 
 
 def transition_unsigned_block(spec, state, block):
-    spec.process_slots(state, block.slot)
+    assert state.slot < block.slot  # Preserve assertion from state transition to avoid strange pre-states from testing
+    if state.slot < block.slot:
+        spec.process_slots(state, block.slot)
+    assert state.latest_block_header.slot < block.slot  # There may not already be a block in this slot or past it.
+    assert state.slot == block.slot  # The block must be for this slot
     spec.process_block(state, block)
 
 
-def apply_empty_block(spec, state):
+def apply_empty_block(spec, state, slot=None):
     """
     Transition via an empty block (on current slot, assuming no block has been applied yet).
     """
-    block = build_empty_block(spec, state)
+    block = build_empty_block(spec, state, slot)
     transition_unsigned_block(spec, state, block)
 
 
@@ -73,7 +78,7 @@ def build_empty_block(spec, state, slot=None):
         slot = state.slot
     if slot < state.slot:
         raise Exception("build_empty_block cannot build blocks for past slots")
-    if slot > state.slot:
+    if state.slot < slot:
         # transition forward in copied state to grab relevant data from state
         state = state.copy()
         spec.process_slots(state, slot)

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

@@ -1,5 +1,5 @@
 from eth2spec.test.context import expect_assertion_error
-from eth2spec.test.helpers.block import sign_block, transition_unsigned_block
+from eth2spec.test.helpers.block import apply_empty_block, sign_block, transition_unsigned_block
 
 
 def get_balance(state, index):
@@ -17,7 +17,8 @@ def next_slots(spec, state, slots):
     """
     Transition given slots forward.
     """
-    spec.process_slots(state, state.slot + slots)
+    if slots > 0:
+        spec.process_slots(state, state.slot + slots)
 
 
 def transition_to(spec, state, slot):
@@ -30,12 +31,29 @@ def transition_to(spec, state, slot):
     assert state.slot == slot
 
 
+def transition_to_slot_via_block(spec, state, slot):
+    """
+    Transition to ``slot`` via an empty block transition
+    """
+    assert state.slot < slot
+    apply_empty_block(spec, state, slot)
+    assert state.slot == slot
+
+
 def next_epoch(spec, state):
     """
     Transition to the start slot of the next epoch
     """
     slot = state.slot + spec.SLOTS_PER_EPOCH - (state.slot % spec.SLOTS_PER_EPOCH)
-    spec.process_slots(state, slot)
+    if slot > state.slot:
+        spec.process_slots(state, slot)
+
+
+def next_epoch_via_block(spec, state):
+    """
+    Transition to the start slot of the next epoch via a full block transition
+    """
+    apply_empty_block(spec, state, state.slot + spec.SLOTS_PER_EPOCH - state.slot % spec.SLOTS_PER_EPOCH)
 
 
 def get_state_root(spec, state, slot) -> bytes:

tests/core/pyspec/eth2spec/test/phase_0/block_processing/test_process_attestation.py

@@ -15,10 +15,9 @@
 from eth2spec.test.helpers.state import (
     next_slot,
     next_slots,
-    next_epoch,
-    transition_to,
+    next_epoch_via_block,
+    transition_to_slot_via_block,
 )
-from eth2spec.test.helpers.block import apply_empty_block
 from eth2spec.utils.ssz.ssz_typing import Bitlist
 
 
@@ -47,9 +46,7 @@ def test_success_multi_proposer_index_iterations(spec, state):
 @spec_state_test
 def test_success_previous_epoch(spec, state):
     attestation = get_valid_attestation(spec, state, signed=True, on_time=False)
-    transition_to(spec, state, spec.SLOTS_PER_EPOCH - 1)
-    next_epoch(spec, state)
-    apply_empty_block(spec, state)
+    next_epoch_via_block(spec, state)
 
     yield from run_attestation_processing(spec, state, attestation)
 
@@ -79,8 +76,7 @@ def test_after_epoch_slots(spec, state):
     attestation = get_valid_attestation(spec, state, signed=True, on_time=False)
 
     # increment past latest inclusion slot
-    transition_to(spec, state, state.slot + spec.SLOTS_PER_EPOCH + 1)
-    apply_empty_block(spec, state)
+    transition_to_slot_via_block(spec, state, state.slot + spec.SLOTS_PER_EPOCH + 1)
 
     yield from run_attestation_processing(spec, state, attestation, False)
 
@@ -151,8 +147,8 @@ def test_invalid_index(spec, state):
 @with_all_phases
 @spec_state_test
 def test_mismatched_target_and_slot(spec, state):
-    next_epoch(spec, state)
-    next_epoch(spec, state)
+    next_epoch_via_block(spec, state)
+    next_epoch_via_block(spec, state)
 
     attestation = get_valid_attestation(spec, state, on_time=False)
     attestation.data.slot = attestation.data.slot - spec.SLOTS_PER_EPOCH

tests/core/pyspec/eth2spec/test/phase_0/block_processing/test_process_attester_slashing.py

@@ -5,10 +5,9 @@
 from eth2spec.test.helpers.attestations import sign_indexed_attestation
 from eth2spec.test.helpers.attester_slashings import get_valid_attester_slashing, \
     get_indexed_attestation_participants, get_attestation_2_data, get_attestation_1_data
-from eth2spec.test.helpers.block import apply_empty_block
 from eth2spec.test.helpers.state import (
     get_balance,
-    next_epoch,
+    next_epoch_via_block,
 )
 
 
@@ -91,8 +90,7 @@ def test_success_double(spec, state):
 @with_all_phases
 @spec_state_test
 def test_success_surround(spec, state):
-    next_epoch(spec, state)
-    apply_empty_block(spec, state)
+    next_epoch_via_block(spec, state)
 
     state.current_justified_checkpoint.epoch += 1
     attester_slashing = get_valid_attester_slashing(spec, state, signed_1=False, signed_2=True)

tests/core/pyspec/eth2spec/test/phase_0/block_processing/test_process_block_header.py

@@ -9,15 +9,16 @@ def prepare_state_for_header_processing(spec, state):
     spec.process_slots(state, state.slot + 1)
 
 
-def run_block_header_processing(spec, state, block, valid=True):
+def run_block_header_processing(spec, state, block, prepare_state=True, valid=True):
     """
     Run ``process_block_header``, yielding:
       - pre-state ('pre')
       - block ('block')
       - post-state ('post').
     If ``valid == False``, run expecting ``AssertionError``
     """
-    prepare_state_for_header_processing(spec, state)
+    if prepare_state:
+        prepare_state_for_header_processing(spec, state)
 
     yield 'pre', state
     yield 'block', block
@@ -68,6 +69,22 @@ def test_invalid_parent_root(spec, state):
     yield from run_block_header_processing(spec, state, block, valid=False)
 
 
+@with_all_phases
+@spec_state_test
+def test_invalid_multiple_blocks_single_slot(spec, state):
+    block = build_empty_block_for_next_slot(spec, state)
+
+    prepare_state_for_header_processing(spec, state)
+    spec.process_block_header(state, block)
+
+    assert state.latest_block_header.slot == state.slot
+
+    child_block = block.copy()
+    child_block.parent_root = block.hash_tree_root()
+
+    yield from run_block_header_processing(spec, state, child_block, prepare_state=False, valid=False)
+
+
 @with_all_phases
 @spec_state_test
 def test_proposer_slashed(spec, state):

tests/core/pyspec/eth2spec/test/phase_0/epoch_processing/run_epoch_process_base.py

@@ -18,7 +18,8 @@ def run_epoch_processing_to(spec, state, process_name: str):
     slot = state.slot + (spec.SLOTS_PER_EPOCH - state.slot % spec.SLOTS_PER_EPOCH)
 
     # transition state to slot before epoch state transition
-    spec.process_slots(state, slot - 1)
+    if state.slot < slot - 1:
+        spec.process_slots(state, slot - 1)
 
     # start transitioning, do one slot update before the epoch itself.
     spec.process_slot(state)

tests/core/pyspec/eth2spec/test/phase_1/block_processing/test_process_early_derived_secret_reveal.py

@@ -1,6 +1,5 @@
 from eth2spec.test.helpers.custody import get_valid_early_derived_secret_reveal
-from eth2spec.test.helpers.block import apply_empty_block
-from eth2spec.test.helpers.state import next_epoch, get_balance
+from eth2spec.test.helpers.state import next_epoch_via_block, get_balance
 from eth2spec.test.context import (
     PHASE0,
     with_all_phases_except,
@@ -64,8 +63,7 @@ def test_reveal_from_current_epoch(spec, state):
 @spec_state_test
 @never_bls
 def test_reveal_from_past_epoch(spec, state):
-    next_epoch(spec, state)
-    apply_empty_block(spec, state)
+    next_epoch_via_block(spec, state)
     randao_key_reveal = get_valid_early_derived_secret_reveal(spec, state, spec.get_current_epoch(state) - 1)
 
     yield from run_early_derived_secret_reveal_processing(spec, state, randao_key_reveal, False)