justification/finalization testing groundwork

test_libs/pyspec/eth2spec/test/phase_0/epoch_processing/test_process_justification_and_finalization.py

@@ -0,0 +1,74 @@
+from eth2spec.test.context import spec_state_test, with_all_phases
+from eth2spec.test.phase_0.epoch_processing.run_epoch_process_base import (
+    run_epoch_processing_with
+)
+
+
+def run_process_just_and_fin(spec, state):
+    yield from run_epoch_processing_with(spec, state, 'process_justification_and_finalization')
+
+
+def get_committee_size(spec, state, slot):
+    epoch = spec.slot_to_epoch(slot)
+    epoch_start_shard = spec.get_epoch_start_shard(state, epoch)
+    committees_per_slot = spec.get_epoch_committee_count(state, epoch) // spec.SLOTS_PER_EPOCH
+    shard = (epoch_start_shard + committees_per_slot * (slot % spec.SLOTS_PER_EPOCH)) % spec.SHARD_COUNT
+    committee_index = (shard + spec.SHARD_COUNT - spec.get_epoch_start_shard(state, epoch)) % spec.SHARD_COUNT
+    committee_count = spec.get_epoch_committee_count(state, epoch)
+    indices = spec.get_active_validator_indices(state, epoch)
+    start = (len(indices) * committee_index) // committee_count
+    end = (len(indices) * (committee_index + 1)) // committee_count
+    size = end - start
+    return size
+
+
+def add_mock_attestations(spec, state, target_epoch, att_count, att_ratio):
+    # we must be at the end of the epoch
+    assert (state.slot + 1) % spec.SLOTS_PER_EPOCH == 0
+
+    previous_epoch = spec.get_previous_epoch(state)
+    current_epoch = spec.get_current_epoch(state)
+
+    if current_epoch == target_epoch:
+        attestations = state.current_epoch_attestations
+    elif previous_epoch == target_epoch:
+        attestations = state.previous_epoch_attestations
+    else:
+        raise Exception(f"cannot target epoch ${target_epoch} from epoch ${current_epoch}")
+
+    total = 0
+    while total < att_count:
+        for i in range(spec.SLOTS_PER_EPOCH):
+            size = get_committee_size(spec, state, state.slot + i)
+            # Create a bitfield filled with the given count per attestation,
+            #  exactly on the right-most part of the committee field.
+            attesting_count = int(size * att_ratio)
+            aggregation_bitfield = ((1 << attesting_count) - 1).to_bytes(length=((size + 7) // 8), byteorder='big')
+
+            attestations.append(spec.PendingAttestation(
+                aggregation_bitfield=aggregation_bitfield,
+                data=spec.AttestationData(
+                    beacon_block_root=b'\xaa' * 32,
+                    source_epoch=0,
+                    source_root=b'\xbb' * 32,
+                    target_root=b'\xbb' * 32,
+                    crosslink=spec.Crosslink()
+                ),
+                inclusion_delay=0,
+            ))
+            total += 1
+
+
+@with_all_phases
+@spec_state_test
+def test_rule_1(spec, state):
+    previous_epoch = spec.get_previous_epoch(state)
+    current_epoch = spec.get_current_epoch(state)
+
+    # TODO
+    # add_mock_attestations(spec, state, ...)
+    # get indices attesting e.g. current_epoch_attestations
+    # set their balances
+    # yield from run_process_just_and_fin(spec, state)
+    # check finalization
+