Update `ExecutionLayerExit` fields: replace `validator_index` with `validator_pubkey`

specs/_features/eip7002/beacon-chain.md

@@ -53,7 +53,7 @@ This mechanism relies on the changes proposed by [EIP-7002](http://eips.ethereum
 ```python
 class ExecutionLayerExit(Container):
     source_address: ExecutionAddress
-    validator_index: ValidatorIndex
+    validator_pubkey: BLSPubkey
 ```
 
 ### Extended Containers
@@ -238,7 +238,9 @@ def process_operations(state: BeaconState, body: BeaconBlockBody) -> None:
 
 ```python
 def process_execution_layer_exit(state: BeaconState, execution_layer_exit: ExecutionLayerExit) -> None:
-    validator = state.validators[execution_layer_exit.validator_index]
+    validator_pubkeys = [v.pubkey for v in state.validators]
+    validator_index = ValidatorIndex(validator_pubkeys.index(execution_layer_exit.validator_pubkey))
+    validator = state.validators[validator_index]
 
     # Verify withdrawal credentials
     is_correct_source_address = (
@@ -258,7 +260,7 @@ def process_execution_layer_exit(state: BeaconState, execution_layer_exit: Execu
         return
 
     # Initiate exit
-    initiate_validator_exit(state, execution_layer_exit.validator_index)
+    initiate_validator_exit(state, validator_index)
 ```
 
 ## Testing

tests/core/pyspec/eth2spec/test/eip7002/block_processing/test_process_execution_layer_exit.py

@@ -11,11 +11,12 @@ def test_basic_exit(spec, state):
 
     current_epoch = spec.get_current_epoch(state)
     validator_index = spec.get_active_validator_indices(state, current_epoch)[0]
+    validator_pubkey = state.validators[validator_index].pubkey
     address = b'\x22' * 20
     set_eth1_withdrawal_credential_with_balance(spec, state, validator_index, address=address)
     execution_layer_exit = spec.ExecutionLayerExit(
         source_address=address,
-        validator_index=validator_index,
+        validator_pubkey=validator_pubkey,
     )
 
     yield from run_execution_layer_exit_processing(spec, state, execution_layer_exit)
@@ -29,12 +30,13 @@ def test_incorrect_source_address(spec, state):
 
     current_epoch = spec.get_current_epoch(state)
     validator_index = spec.get_active_validator_indices(state, current_epoch)[0]
+    validator_pubkey = state.validators[validator_index].pubkey
     address = b'\x22' * 20
     incorrect_address = b'\x33' * 20
     set_eth1_withdrawal_credential_with_balance(spec, state, validator_index, address=address)
     execution_layer_exit = spec.ExecutionLayerExit(
         source_address=incorrect_address,
-        validator_index=validator_index,
+        validator_pubkey=validator_pubkey,
     )
 
     yield from run_execution_layer_exit_processing(spec, state, execution_layer_exit, success=False)

tests/core/pyspec/eth2spec/test/eip7002/sanity/test_blocks.py

@@ -24,11 +24,12 @@ def test_basic_exit(spec, state):
 
     current_epoch = spec.get_current_epoch(state)
     validator_index = spec.get_active_validator_indices(state, current_epoch)[0]
+    validator_pubkey = state.validators[validator_index].pubkey
     address = b'\x22' * 20
     set_eth1_withdrawal_credential_with_balance(spec, state, validator_index, address=address)
     execution_layer_exit = spec.ExecutionLayerExit(
         source_address=address,
-        validator_index=validator_index,
+        validator_pubkey=validator_pubkey,
     )
 
     yield 'pre', state

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

@@ -1,4 +1,5 @@
 from eth2spec.test.context import expect_assertion_error
+from eth2spec.test.helpers.state import get_validator_index_by_pubkey
 
 
 #
@@ -14,7 +15,7 @@ def run_execution_layer_exit_processing(spec, state, execution_layer_exit, valid
       - post-state ('post').
     If ``valid == False``, run expecting ``AssertionError``
     """
-    validator_index = execution_layer_exit.validator_index
+    validator_index = get_validator_index_by_pubkey(state, execution_layer_exit.validator_pubkey)
 
     yield 'pre', state
     yield 'execution_layer_exit', execution_layer_exit

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

@@ -141,8 +141,8 @@ def get_exit_rlp(exit):
     exit_rlp = [
         # source_address
         (Binary(20, 20), exit.source_address),
-        # validator_index
-        (big_endian_int, exit.validator_index),
+        # validator_pubkey
+        (Binary(48, 48), exit.validator_pubkey),
     ]
 
     sedes = List([schema for schema, _ in exit_rlp])

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

@@ -166,3 +166,8 @@ def has_active_balance_differential(spec, state):
     active_balance = spec.get_total_active_balance(state)
     total_balance = spec.get_total_balance(state, set(range(len(state.validators))))
     return active_balance // spec.EFFECTIVE_BALANCE_INCREMENT != total_balance // spec.EFFECTIVE_BALANCE_INCREMENT
+
+
+def get_validator_index_by_pubkey(state, pubkey):
+    index = next((i for i, validator in enumerate(state.validators) if validator.pubkey == pubkey), None)
+    return index