Fix process_registry_updates and add test_process_registry_updates

specs/core/0_beacon-chain.md

@@ -1562,6 +1562,7 @@ def process_registry_updates(state: BeaconState) -> None:
     ], key=lambda index: state.validator_registry[index].activation_eligibility_epoch)
     # Dequeued validators for activation up to churn limit (without resetting activation epoch)
     for index in activation_queue[:get_churn_limit(state)]:
+        validator = state.validator_registry[index]
         if validator.activation_epoch == FAR_FUTURE_EPOCH:
             validator.activation_epoch = get_delayed_activation_exit_epoch(get_current_epoch(state))
 ```

specs/validator/0_beacon-chain-validator.md

@@ -224,7 +224,7 @@ Up to `MAX_ATTESTATIONS` aggregate attestations can be included in the `block`.
 
 ##### Deposits
 
-If there are any unprocessed deposits for the existing `state.latest_eth1_data` (i.e. `state.latest_eth1_data.deposit_count > state.deposit_index`), then pending deposits _must_ be added to the block. The expected number of deposits is exactly `min(MAX_DEPOSITS, latest_eth1_data.deposit_count - state.deposit_index)`.  These [`deposits`](../core/0_beacon-chain.md#deposit) are constructed from the `Deposit` logs from the [Eth1.0 deposit contract](../core/0_deposit-contract.md) and must be processed in sequential order. The deposits included in the `block` must satisfy the verification conditions found in [deposits processing](../core/0_beacon-chain.md#deposits).
+If there are any unprocessed deposits for the existing `state.latest_eth1_data` (i.e. `state.latest_eth1_data.deposit_count > state.deposit_index`), then pending deposits _must_ be added to the block. The expected number of deposits is exactly `min(MAX_DEPOSITS, latest_eth1_data.deposit_count - state.deposit_index)`.  These [`deposits`](../core/0_beacon-chain.md#deposit) are constructed from the `Deposit` logs from the [Eth1.0 deposit contract](../core/0_deposit-contract) and must be processed in sequential order. The deposits included in the `block` must satisfy the verification conditions found in [deposits processing](../core/0_beacon-chain.md#deposits).
 
 The `proof` for each deposit must be constructed against the deposit root contained in `state.latest_eth1_data` rather than the deposit root at the time the deposit was initially logged from the 1.0 chain. This entails storing a full deposit merkle tree locally and computing updated proofs against the `latest_eth1_data.deposit_root` as needed. See [`minimal_merkle.py`](https://github.com/ethereum/research/blob/master/spec_pythonizer/utils/merkle_minimal.py) for a sample implementation.
 

test_libs/pyspec/tests/epoch_processing/test_process_registry_updates.py

@@ -0,0 +1,67 @@
+from copy import deepcopy
+
+import pytest
+
+import eth2spec.phase0.spec as spec
+
+from eth2spec.phase0.spec import (
+    get_current_epoch,
+    is_active_validator,
+)
+from tests.helpers import (
+    next_epoch,
+)
+
+# mark entire file as 'state'
+pytestmark = pytest.mark.state
+
+
+def test_activation(state):
+    index = 0
+    assert is_active_validator(state.validator_registry[index], get_current_epoch(state))
+
+    # Mock a new deposit
+    state.validator_registry[index].activation_eligibility_epoch = spec.FAR_FUTURE_EPOCH
+    state.validator_registry[index].activation_epoch = spec.FAR_FUTURE_EPOCH
+    state.validator_registry[index].effective_balance = spec.MAX_EFFECTIVE_BALANCE
+    assert not is_active_validator(state.validator_registry[index], get_current_epoch(state))
+
+    pre_state = deepcopy(state)
+
+    blocks = []
+    for _ in range(spec.ACTIVATION_EXIT_DELAY + 1):
+        block = next_epoch(state)
+        blocks.append(block)
+
+    assert state.validator_registry[index].activation_eligibility_epoch != spec.FAR_FUTURE_EPOCH
+    assert state.validator_registry[index].activation_epoch != spec.FAR_FUTURE_EPOCH
+    assert is_active_validator(
+        state.validator_registry[index],
+        get_current_epoch(state),
+    )
+
+    return pre_state, blocks, state
+
+
+def test_ejection(state):
+    index = 0
+    assert is_active_validator(state.validator_registry[index], get_current_epoch(state))
+    assert state.validator_registry[index].exit_epoch == spec.FAR_FUTURE_EPOCH
+
+    # Mock an ejection
+    state.validator_registry[index].effective_balance = spec.EJECTION_BALANCE
+
+    pre_state = deepcopy(state)
+
+    blocks = []
+    for _ in range(spec.ACTIVATION_EXIT_DELAY + 1):
+        block = next_epoch(state)
+        blocks.append(block)
+
+    assert state.validator_registry[index].exit_epoch != spec.FAR_FUTURE_EPOCH
+    assert not is_active_validator(
+        state.validator_registry[index],
+        get_current_epoch(state),
+    )
+
+    return pre_state, blocks, state

test_libs/pyspec/tests/helpers.py

@@ -402,11 +402,21 @@ def add_attestation_to_state(state, attestation, slot):
 
 
 def next_slot(state):
+    """
+    Transition to the next slot via an empty block.
+    Return the empty block that triggered the transition.
+    """
     block = build_empty_block_for_next_slot(state)
     state_transition(state, block)
+    return block
 
 
 def next_epoch(state):
+    """
+    Transition to the start slot of the next epoch via an empty block.
+    Return the empty block that triggered the transition.
+    """
     block = build_empty_block_for_next_slot(state)
     block.slot += spec.SLOTS_PER_EPOCH - (state.slot % spec.SLOTS_PER_EPOCH)
     state_transition(state, block)
+    return block