Arbitrary trait for eth2/types (#1040)

* Add the arbitrary type to eth2/types and their deps

Signed-off-by: Kirk Baird <baird.k@outlook.com>

* Wrap arbitrary in a feature flag

Signed-off-by: Kirk Baird <baird.k@outlook.com>

* Fix feature for types

Signed-off-by: Kirk Baird <baird.k@outlook.com>

* Fix comment

Signed-off-by: Kirk Baird <baird.k@outlook.com>

* Patch versioning

Signed-off-by: Kirk Baird <baird.k@outlook.com>

* Allow expanded crate reference for arbitrary 0.4.3

Signed-off-by: Kirk Baird <baird.k@outlook.com>

* Add arbitrary to remaining types

Signed-off-by: Kirk Baird <baird.k@outlook.com>

* use cmp::min

Signed-off-by: Kirk Baird <baird.k@outlook.com>

* Derive Arbitrary trait for ValidatorStatus, TotalBalances and InclusionInfo

* Add CI check for state processing arbitrary faetures

Signed-off-by: Kirk Baird <baird.k@outlook.com>

* Fix indentation

Signed-off-by: Kirk Baird <baird.k@outlook.com>

Co-authored-by: Mehdi Zerouali <mehdi@sigmaprime.io>

eth2/types/src/aggregate_and_proof.rs

@@ -11,6 +11,7 @@ use tree_hash_derive::TreeHash;
 /// A Validators aggregate attestation and selection proof.
 ///
 /// Spec v0.10.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Encode, Decode, TestRandom, TreeHash)]
 #[serde(bound = "T: EthSpec")]
 pub struct AggregateAndProof<T: EthSpec> {

eth2/types/src/attestation.rs

@@ -20,6 +20,7 @@ pub enum Error {
 /// Details an attestation that can be slashable.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 #[serde(bound = "T: EthSpec")]
 pub struct Attestation<T: EthSpec> {

eth2/types/src/attestation_data.rs

@@ -9,6 +9,7 @@ use tree_hash_derive::TreeHash;
 /// The data upon which an attestation is based.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(
     Debug,
     Clone,

eth2/types/src/attestation_duty.rs

@@ -1,6 +1,7 @@
 use crate::*;
 use serde_derive::{Deserialize, Serialize};
 
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, PartialEq, Clone, Copy, Default, Serialize, Deserialize)]
 pub struct AttestationDuty {
     /// The slot during which the attester must attest.

eth2/types/src/attester_slashing.rs

@@ -8,6 +8,7 @@ use tree_hash_derive::TreeHash;
 /// Two conflicting attestations.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 #[serde(bound = "T: EthSpec")]
 pub struct AttesterSlashing<T: EthSpec> {

eth2/types/src/beacon_block.rs

@@ -11,6 +11,7 @@ use tree_hash_derive::TreeHash;
 /// A block of the `BeaconChain`.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 #[serde(bound = "T: EthSpec")]
 pub struct BeaconBlock<T: EthSpec> {

eth2/types/src/beacon_block_body.rs

@@ -11,6 +11,7 @@ use tree_hash_derive::TreeHash;
 /// The body of a `BeaconChain` block, containing operations.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 #[serde(bound = "T: EthSpec")]
 pub struct BeaconBlockBody<T: EthSpec> {

eth2/types/src/beacon_block_header.rs

@@ -10,6 +10,7 @@ use tree_hash_derive::TreeHash;
 /// A header of a `BeaconBlock`.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 pub struct BeaconBlockHeader {
     pub slot: Slot,

eth2/types/src/beacon_committee.rs

@@ -17,6 +17,7 @@ impl<'a> BeaconCommittee<'a> {
     }
 }
 
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Default, Clone, Debug, PartialEq)]
 pub struct OwnedBeaconCommittee {
     pub slot: Slot,

eth2/types/src/beacon_state.rs

@@ -2,6 +2,7 @@ use self::committee_cache::get_active_validator_indices;
 use self::exit_cache::ExitCache;
 use crate::test_utils::TestRandom;
 use crate::*;
+
 use cached_tree_hash::{CacheArena, CachedTreeHash};
 use compare_fields_derive::CompareFields;
 use eth2_hashing::hash;
@@ -102,6 +103,7 @@ impl AllowNextEpoch {
     }
 }
 
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(PartialEq, Eq, Hash, Clone, Copy)]
 pub struct BeaconStateHash(Hash256);
 
@@ -1155,3 +1157,46 @@ impl From<ArithError> for Error {
         Error::ArithError(e)
     }
 }
+
+#[cfg(feature = "arbitrary-fuzz")]
+impl<T: EthSpec> arbitrary::Arbitrary for BeaconState<T> {
+    fn arbitrary(u: &mut arbitrary::Unstructured<'_>) -> arbitrary::Result<Self> {
+        Ok(Self {
+            genesis_time: u64::arbitrary(u)?,
+            genesis_validators_root: Hash256::arbitrary(u)?,
+            slot: Slot::arbitrary(u)?,
+            fork: Fork::arbitrary(u)?,
+            latest_block_header: BeaconBlockHeader::arbitrary(u)?,
+            block_roots: <FixedVector<Hash256, T::SlotsPerHistoricalRoot>>::arbitrary(u)?,
+            state_roots: <FixedVector<Hash256, T::SlotsPerHistoricalRoot>>::arbitrary(u)?,
+            historical_roots: <VariableList<Hash256, T::HistoricalRootsLimit>>::arbitrary(u)?,
+            eth1_data: Eth1Data::arbitrary(u)?,
+            eth1_data_votes: <VariableList<Eth1Data, T::SlotsPerEth1VotingPeriod>>::arbitrary(u)?,
+            eth1_deposit_index: u64::arbitrary(u)?,
+            validators: <VariableList<Validator, T::ValidatorRegistryLimit>>::arbitrary(u)?,
+            balances: <VariableList<u64, T::ValidatorRegistryLimit>>::arbitrary(u)?,
+            randao_mixes: <FixedVector<Hash256, T::EpochsPerHistoricalVector>>::arbitrary(u)?,
+            slashings: <FixedVector<u64, T::EpochsPerSlashingsVector>>::arbitrary(u)?,
+            previous_epoch_attestations: <VariableList<
+                PendingAttestation<T>,
+                T::MaxPendingAttestations,
+            >>::arbitrary(u)?,
+            current_epoch_attestations: <VariableList<
+                PendingAttestation<T>,
+                T::MaxPendingAttestations,
+            >>::arbitrary(u)?,
+            justification_bits: <BitVector<T::JustificationBitsLength>>::arbitrary(u)?,
+            previous_justified_checkpoint: Checkpoint::arbitrary(u)?,
+            current_justified_checkpoint: Checkpoint::arbitrary(u)?,
+            finalized_checkpoint: Checkpoint::arbitrary(u)?,
+            committee_caches: [
+                CommitteeCache::arbitrary(u)?,
+                CommitteeCache::arbitrary(u)?,
+                CommitteeCache::arbitrary(u)?,
+            ],
+            pubkey_cache: PubkeyCache::arbitrary(u)?,
+            exit_cache: ExitCache::arbitrary(u)?,
+            tree_hash_cache: None,
+        })
+    }
+}

eth2/types/src/beacon_state/committee_cache.rs

@@ -277,3 +277,10 @@ pub fn get_active_validator_indices(validators: &[Validator], epoch: Epoch) -> V
 
     active
 }
+
+#[cfg(feature = "arbitrary-fuzz")]
+impl arbitrary::Arbitrary for CommitteeCache {
+    fn arbitrary(_u: &mut arbitrary::Unstructured<'_>) -> arbitrary::Result<Self> {
+        Ok(Self::default())
+    }
+}

eth2/types/src/beacon_state/exit_cache.rs

@@ -70,3 +70,10 @@ impl ExitCache {
         Ok(self.exits_per_epoch.get(&epoch).cloned().unwrap_or(0))
     }
 }
+
+#[cfg(feature = "arbitrary-fuzz")]
+impl arbitrary::Arbitrary for ExitCache {
+    fn arbitrary(_u: &mut arbitrary::Unstructured<'_>) -> arbitrary::Result<Self> {
+        Ok(Self::default())
+    }
+}

eth2/types/src/beacon_state/pubkey_cache.rs

@@ -39,3 +39,10 @@ impl PubkeyCache {
         self.map.get(pubkey).copied()
     }
 }
+
+#[cfg(feature = "arbitrary-fuzz")]
+impl arbitrary::Arbitrary for PubkeyCache {
+    fn arbitrary(_u: &mut arbitrary::Unstructured<'_>) -> arbitrary::Result<Self> {
+        Ok(Self::default())
+    }
+}

eth2/types/src/chain_spec.rs

@@ -26,6 +26,7 @@ pub enum Domain {
 /// Holds all the "constants" for a BeaconChain.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(PartialEq, Debug, Clone, Serialize, Deserialize)]
 #[serde(default)]
 pub struct ChainSpec {

eth2/types/src/checkpoint.rs

@@ -8,6 +8,7 @@ use tree_hash_derive::TreeHash;
 /// Casper FFG checkpoint, used in attestations.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(
     Debug,
     Clone,

eth2/types/src/deposit.rs

@@ -1,9 +1,8 @@
 use crate::test_utils::TestRandom;
 use crate::*;
-use ssz_types::typenum::U33;
-
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
+use ssz_types::typenum::U33;
 use test_random_derive::TestRandom;
 use tree_hash_derive::TreeHash;
 
@@ -12,6 +11,7 @@ pub const DEPOSIT_TREE_DEPTH: usize = 32;
 /// A deposit to potentially become a beacon chain validator.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 pub struct Deposit {
     pub proof: FixedVector<Hash256, U33>,

eth2/types/src/deposit_data.rs

@@ -1,7 +1,7 @@
 use crate::test_utils::TestRandom;
 use crate::*;
-use bls::{PublicKeyBytes, SignatureBytes};
 
+use bls::{PublicKeyBytes, SignatureBytes};
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
@@ -10,6 +10,7 @@ use tree_hash_derive::TreeHash;
 /// The data supplied by the user to the deposit contract.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 pub struct DepositData {
     pub pubkey: PublicKeyBytes,

eth2/types/src/deposit_message.rs

@@ -1,7 +1,7 @@
 use crate::test_utils::TestRandom;
 use crate::*;
-use bls::PublicKeyBytes;
 
+use bls::PublicKeyBytes;
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
@@ -10,6 +10,7 @@ use tree_hash_derive::TreeHash;
 /// The data supplied by the user to the deposit contract.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 pub struct DepositMessage {
     pub pubkey: PublicKeyBytes,

eth2/types/src/enr_fork_id.rs

@@ -11,6 +11,7 @@ use tree_hash_derive::TreeHash;
 /// a nodes local ENR.
 ///
 /// Spec v0.11
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(
     Debug, Clone, PartialEq, Default, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom,
 )]

eth2/types/src/eth1_data.rs

@@ -9,6 +9,7 @@ use tree_hash_derive::TreeHash;
 /// Contains data obtained from the Eth1 chain.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(
     Debug,
     PartialEq,

eth2/types/src/eth_spec.rs

@@ -1,4 +1,5 @@
 use crate::*;
+
 use safe_arith::SafeArith;
 use serde_derive::{Deserialize, Serialize};
 use ssz_types::typenum::{
@@ -131,6 +132,7 @@ macro_rules! params_from_eth_spec {
 /// Ethereum Foundation specifications.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Clone, PartialEq, Debug, Default, Serialize, Deserialize)]
 pub struct MainnetEthSpec;
 
@@ -164,6 +166,7 @@ pub type FoundationBeaconState = BeaconState<MainnetEthSpec>;
 /// Ethereum Foundation minimal spec, as defined in the eth2.0-specs repo.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Clone, PartialEq, Debug, Default, Serialize, Deserialize)]
 pub struct MinimalEthSpec;
 
@@ -198,6 +201,7 @@ impl EthSpec for MinimalEthSpec {
 pub type MinimalBeaconState = BeaconState<MinimalEthSpec>;
 
 /// Interop testnet spec
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Clone, PartialEq, Debug, Default, Serialize, Deserialize)]
 pub struct InteropEthSpec;
 

eth2/types/src/fork.rs

@@ -10,6 +10,7 @@ use tree_hash_derive::TreeHash;
 /// Specifies a fork of the `BeaconChain`, to prevent replay attacks.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(
     Debug, Clone, PartialEq, Default, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom,
 )]

eth2/types/src/fork_data.rs

@@ -10,6 +10,7 @@ use tree_hash_derive::TreeHash;
 /// Specifies a fork of the `BeaconChain`, to prevent replay attacks.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(
     Debug, Clone, PartialEq, Default, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom,
 )]

eth2/types/src/free_attestation.rs

@@ -4,6 +4,7 @@
 use super::{AttestationData, Signature};
 use serde_derive::Serialize;
 
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, Clone, PartialEq, Serialize)]
 pub struct FreeAttestation {
     pub data: AttestationData,

eth2/types/src/historical_batch.rs

@@ -10,6 +10,7 @@ use tree_hash_derive::TreeHash;
 /// Historical block and state roots.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 pub struct HistoricalBatch<T: EthSpec> {
     pub block_roots: FixedVector<Hash256, T::SlotsPerHistoricalRoot>,

eth2/types/src/indexed_attestation.rs

@@ -1,4 +1,5 @@
 use crate::{test_utils::TestRandom, AggregateSignature, AttestationData, EthSpec, VariableList};
+
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
@@ -9,6 +10,7 @@ use tree_hash_derive::TreeHash;
 /// To be included in an `AttesterSlashing`.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 #[serde(bound = "T: EthSpec")]
 pub struct IndexedAttestation<T: EthSpec> {

eth2/types/src/pending_attestation.rs

@@ -17,6 +17,18 @@ pub struct PendingAttestation<T: EthSpec> {
     pub proposer_index: u64,
 }
 
+#[cfg(feature = "arbitrary-fuzz")]
+impl<T: EthSpec> arbitrary::Arbitrary for PendingAttestation<T> {
+    fn arbitrary(u: &mut arbitrary::Unstructured<'_>) -> arbitrary::Result<Self> {
+        Ok(Self {
+            aggregation_bits: <BitList<T::MaxValidatorsPerCommittee>>::arbitrary(u)?,
+            data: AttestationData::arbitrary(u)?,
+            inclusion_delay: u64::arbitrary(u)?,
+            proposer_index: u64::arbitrary(u)?,
+        })
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

eth2/types/src/proposer_slashing.rs

@@ -9,6 +9,7 @@ use tree_hash_derive::TreeHash;
 /// Two conflicting proposals from the same proposer (validator).
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 pub struct ProposerSlashing {
     pub signed_header_1: SignedBeaconBlockHeader,

eth2/types/src/relative_epoch.rs

@@ -6,10 +6,14 @@ pub enum Error {
     EpochTooHigh { base: Epoch, other: Epoch },
 }
 
+#[cfg(feature = "arbitrary-fuzz")]
+use arbitrary::Arbitrary;
+
 /// Defines the epochs relative to some epoch. Most useful when referring to the committees prior
 /// to and following some epoch.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(Arbitrary))]
 #[derive(Debug, PartialEq, Clone, Copy)]
 pub enum RelativeEpoch {
     /// The prior epoch.

eth2/types/src/selection_proof.rs

@@ -3,6 +3,7 @@ use safe_arith::{ArithError, SafeArith};
 use std::convert::TryInto;
 use tree_hash::TreeHash;
 
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(PartialEq, Debug, Clone)]
 pub struct SelectionProof(Signature);
 

eth2/types/src/signed_aggregate_and_proof.rs

@@ -12,6 +12,7 @@ use tree_hash_derive::TreeHash;
 /// gossipsub topic.
 ///
 /// Spec v0.10.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Encode, Decode, TestRandom, TreeHash)]
 #[serde(bound = "T: EthSpec")]
 pub struct SignedAggregateAndProof<T: EthSpec> {

eth2/types/src/signed_beacon_block.rs

@@ -1,13 +1,13 @@
 use crate::{test_utils::TestRandom, BeaconBlock, EthSpec, Hash256, Slot};
-use bls::Signature;
-
 use std::fmt;
 
+use bls::Signature;
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
 use tree_hash::TreeHash;
 
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(PartialEq, Eq, Hash, Clone, Copy)]
 pub struct SignedBeaconBlockHash(Hash256);
 
@@ -38,6 +38,7 @@ impl From<SignedBeaconBlockHash> for Hash256 {
 /// A `BeaconBlock` and a signature from its proposer.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TestRandom)]
 #[serde(bound = "E: EthSpec")]
 pub struct SignedBeaconBlock<E: EthSpec> {

eth2/types/src/signed_beacon_block_header.rs

@@ -9,6 +9,7 @@ use tree_hash_derive::TreeHash;
 /// An exit voluntarily submitted a validator who wishes to withdraw.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 pub struct SignedBeaconBlockHeader {
     pub message: BeaconBlockHeader,

eth2/types/src/signed_voluntary_exit.rs

@@ -9,6 +9,7 @@ use tree_hash_derive::TreeHash;
 /// An exit voluntarily submitted a validator who wishes to withdraw.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 pub struct SignedVoluntaryExit {
     pub message: VoluntaryExit,

eth2/types/src/signing_root.rs

@@ -1,11 +1,13 @@
 use crate::test_utils::TestRandom;
 use crate::Hash256;
+
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
 use tree_hash::TreeHash;
 use tree_hash_derive::TreeHash;
 
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 pub struct SigningRoot {
     pub object_root: Hash256,

eth2/types/src/slot_epoch.rs

@@ -12,6 +12,7 @@
 
 use crate::test_utils::TestRandom;
 use crate::SignedRoot;
+
 use rand::RngCore;
 use serde_derive::{Deserialize, Serialize};
 use ssz::{ssz_encode, Decode, DecodeError, Encode};
@@ -21,10 +22,12 @@ use std::hash::{Hash, Hasher};
 use std::iter::Iterator;
 use std::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Rem, Sub, SubAssign};
 
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Eq, Clone, Copy, Default, Serialize, Deserialize)]
 #[serde(transparent)]
 pub struct Slot(u64);
 
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Eq, Clone, Copy, Default, Serialize, Deserialize)]
 pub struct Epoch(u64);
 

eth2/types/src/subnet_id.rs

@@ -2,6 +2,7 @@
 use serde_derive::{Deserialize, Serialize};
 use std::ops::{Deref, DerefMut};
 
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
 pub struct SubnetId(u64);
 

eth2/types/src/validator.rs

@@ -9,6 +9,7 @@ use tree_hash_derive::TreeHash;
 /// Information about a `BeaconChain` validator.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Encode, Decode, TestRandom, TreeHash)]
 pub struct Validator {
     pub pubkey: PublicKeyBytes,

eth2/types/src/voluntary_exit.rs

@@ -11,6 +11,7 @@ use tree_hash_derive::TreeHash;
 /// An exit voluntarily submitted a validator who wishes to withdraw.
 ///
 /// Spec v0.11.1
+#[cfg_attr(feature = "arbitrary-fuzz", derive(arbitrary::Arbitrary))]
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 pub struct VoluntaryExit {
     /// Earliest epoch when voluntary exit can be processed.