Advance Beacon State Transition Part 6: Simulate Validator Exits (#1302)

* deposit definition according to latest spec

* ssz decode input data tests

* fix todo

* ignore XXX fields in struct

* fix

* timestamp

* gazelle run processing

* process deposit complete

* all logic complete

* verify merkle branch

* gazelle

* process deposit func

* diff cov 1005

* add todo"

* all test cases written down

* most tests complete

* ttl timestamp fail

* 100% code coverage in deposits

* fix params

* encode deposit data helper func

* state transition with no slots failing with panic at calcnewblockhashes

* smaller deposits for chain start

* state advancement benches

* ran go tests

* bazel

* improve the thing

* lint

* works works works

* all conflicts fixed

* edit readme to specify tests format

* edit readme to specify tests format

* skip slots works yay

* gazelle

* edit readme to specify tests format

* wrapped up all randao simulation

* fix

* passing

* goimports

* move to slices pkg

* deadcode

* deposit yaml tests

* created deposit trie implementation in Go

* created deposit trie implementation in Go

* gazelle

* merkle branch generation

* merkle branch generation

* more merkle debugging

* fix deposit trie

* include new merkle trie functions

* update all deposit operations

* capitalize

* advancing deposits fully works, grows the validator set

* wrap up time formatting

* lint fix

* include all information in the README

* edit conf

* revert

* clean up before merge

* successfully e2e test proposer slashings

* casper advancement

* wrap up casper slashings

* gazelle

* fix conf

* fix comments

* advance validator exits complete

* wrap up readme

beacon-chain/chaintest/README.md

@@ -112,6 +112,7 @@ The following configuration options are available for state transition tests:
 - **deposits**: `[Deposit Config]` trigger a new validator deposit into the beacon state based on configuration options
 - **proposer_slashings**: `[Proposer Slashing Config]` trigger a proposer slashing at a certain slot for a certain proposer index
 - **casper_slashings**: `[Casper Slashing Config]` trigger a casper slashing at a certain slot
+- **validator_exits**: `[Validator Exit Config]` trigger a voluntary validator exit at a certain slot for a validator index
 
 **Deposit Config**
 - **slot**: `int` a slot in which to trigger a deposit during a state transition test
@@ -140,12 +141,17 @@ The following configuration options are available for state transition tests:
 - **votes_2_custody_0_indices**: `[int]` the custody indices 0 for votes2
 - **votes_2_custody_1_indices**: `[int]` the custody indices 1 for votes2
 
+**Validator Exit Config**
+- **slot**: `int` the slot at which a validator wants to voluntarily exit the validator registry
+- **validator_index**: `int` the index of the validator in the registry that is exiting
+
 #### Test Results
 
 The following are **mandatory** fields as they correspond to checks done at the end of the test run.
 - **slot**: `int` check the slot of the state resulting from applying N state transitions in the test
 - **num_validators** `[int]` check the number of validators in the validator registry after applying N state transitions
 - **penalized_validators** `[int]` the list of validator indices we verify were penalized during the test
+- **exited_validators**: `[int]` the list of validator indices we verify voluntarily exited the registry during the test
 
 ## Stateless Tests
 

beacon-chain/chaintest/backend/helpers.go

@@ -26,6 +26,7 @@ func generateSimulatedBlock(
 	depositsTrie *trie.DepositTrie,
 	simulatedProposerSlashing *StateTestProposerSlashing,
 	simulatedCasperSlashing *StateTestCasperSlashing,
+	simulatedExit *StateTestValidatorExit,
 ) (*pb.BeaconBlock, [32]byte, error) {
 	encodedState, err := proto.Marshal(beaconState)
 	if err != nil {
@@ -105,6 +106,12 @@ func generateSimulatedBlock(
 			},
 		})
 	}
+	if simulatedExit != nil {
+		block.Body.Exits = append(block.Body.Exits, &pb.Exit{
+			Slot:           simulatedExit.Slot,
+			ValidatorIndex: simulatedExit.ValidatorIndex,
+		})
+	}
 	encodedBlock, err := proto.Marshal(block)
 	if err != nil {
 		return nil, [32]byte{}, fmt.Errorf("could not marshal new block: %v", err)

beacon-chain/chaintest/backend/simulated_backend.go

@@ -200,6 +200,13 @@ func (sb *SimulatedBackend) RunStateTransitionTest(testCase *StateTestCase) erro
 				break
 			}
 		}
+		var simulatedValidatorExit *StateTestValidatorExit
+		for _, exit := range testCase.Config.ValidatorExits {
+			if exit.Slot == i {
+				simulatedValidatorExit = exit
+				break
+			}
+		}
 
 		layersPeeled := layersPeeledForProposer[proposerIndex]
 		blockRandaoReveal := determineSimulatedBlockRandaoReveal(layersPeeled, hashOnions)
@@ -214,6 +221,7 @@ func (sb *SimulatedBackend) RunStateTransitionTest(testCase *StateTestCase) erro
 			depositsTrie,
 			simulatedProposerSlashing,
 			simulatedCasperSlashing,
+			simulatedValidatorExit,
 		)
 		if err != nil {
 			return fmt.Errorf("could not generate simulated beacon block %v", err)
@@ -266,6 +274,14 @@ func (sb *SimulatedBackend) RunStateTransitionTest(testCase *StateTestCase) erro
 			)
 		}
 	}
+	for _, exited := range testCase.Results.ExitedValidators {
+		if beaconState.ValidatorRegistry[exited].StatusFlags != pb.ValidatorRecord_INITIATED_EXIT {
+			return fmt.Errorf(
+				"expected validator at index %d to have exited",
+				exited,
+			)
+		}
+	}
 	return nil
 }
 

beacon-chain/chaintest/backend/state_test_format.go

@@ -23,6 +23,7 @@ type StateTestConfig struct {
 	Deposits              []*StateTestDeposit          `yaml:"deposits"`
 	ProposerSlashings     []*StateTestProposerSlashing `yaml:"proposer_slashings"`
 	CasperSlashings       []*StateTestCasperSlashing   `yaml:"casper_slashings"`
+	ValidatorExits        []*StateTestValidatorExit    `yaml:"validator_exits"`
 	EpochLength           uint64                       `yaml:"epoch_length"`
 	ShardCount            uint64                       `yaml:"shard_count"`
 	DepositsForChainStart uint64                       `yaml:"deposits_for_chain_start"`
@@ -62,9 +63,16 @@ type StateTestCasperSlashing struct {
 	Votes2CustodyBit1Indices []uint32 `yaml:"votes_2_custody_1_indices"`
 }
 
+// StateTestValidatorExit --
+type StateTestValidatorExit struct {
+	Slot           uint64 `yaml:"slot"`
+	ValidatorIndex uint32 `yaml:"validator_index"`
+}
+
 // StateTestResults --
 type StateTestResults struct {
 	Slot                uint64
 	NumValidators       int      `yaml:"num_validators"`
 	PenalizedValidators []uint32 `yaml:"penalized_validators"`
+	ExitedValidators    []uint32 `yaml:"exited_validators"`
 }

beacon-chain/chaintest/tests/state-tests/block-processing.yaml

@@ -52,10 +52,14 @@ test_cases:
           votes_1_custody_1_indices: []
           votes_2_custody_0_indices: []
           votes_2_custody_1_indices: [16386]
+      validator_exits:
+        - slot: 60
+          validator_index: 100 # At slot 60, validator at index 100 triggers a voluntary exit
     results:
       slot: 64
       num_validators: 16387
       penalized_validators: [16385, 16386] # We test that the validators at indices 16385, 16386 were indeed penalized
+      exited_validators: [100] # We confirm the indices of validators that willingly exited the registry
   - config:
       skip_slots: [10, 20]
       epoch_length: 64

beacon-chain/rpc/service_test.go

@@ -658,7 +658,7 @@ func TestValidatorAssignments(t *testing.T) {
 }
 
 func TestAssignmentsForPublicKeys_emptyPubKey(t *testing.T) {
-	pks := []*pb.PublicKey{&pb.PublicKey{}}
+	pks := []*pb.PublicKey{{}}
 
 	a, err := assignmentsForPublicKeys(pks, nil)
 	if err != nil {