Fix clippy errors on tests (#2160)

## Issue Addressed

There are some clippy error on tests.


## Proposed Changes

Enable clippy check on tests and fix the errors. 💪

consensus/types/src/beacon_state/tests.rs

@@ -1,6 +1,7 @@
 #![cfg(test)]
 use super::*;
 use crate::test_utils::*;
+use std::ops::Mul;
 
 ssz_and_tree_hash_tests!(FoundationBeaconState);
 
@@ -49,13 +50,13 @@ fn test_beacon_proposer_index<T: EthSpec>() {
 
     // Test where we have two validators per slot.
     // 0th candidate should be chosen every time.
-    let state = build_state(T::slots_per_epoch() as usize * 2);
+    let state = build_state((T::slots_per_epoch() as usize).mul(2));
     for i in 0..T::slots_per_epoch() {
         test(&state, Slot::from(i), 0);
     }
 
     // Test with two validators per slot, first validator has zero balance.
-    let mut state = build_state(T::slots_per_epoch() as usize * 2);
+    let mut state = build_state((T::slots_per_epoch() as usize).mul(2));
     let slot0_candidate0 = ith_candidate(&state, Slot::new(0), 0, &spec);
     state.validators[slot0_candidate0].effective_balance = 0;
     test(&state, Slot::new(0), 1);
@@ -74,8 +75,8 @@ fn beacon_proposer_index() {
 /// 1. Using the cache before it's built fails.
 /// 2. Using the cache after it's build passes.
 /// 3. Using the cache after it's dropped fails.
-fn test_cache_initialization<'a, T: EthSpec>(
-    state: &'a mut BeaconState<T>,
+fn test_cache_initialization<T: EthSpec>(
+    state: &mut BeaconState<T>,
     relative_epoch: RelativeEpoch,
     spec: &ChainSpec,
 ) {
@@ -126,7 +127,7 @@ fn cache_initialization() {
 }
 
 fn test_clone_config<E: EthSpec>(base_state: &BeaconState<E>, clone_config: CloneConfig) {
-    let state = base_state.clone_with(clone_config.clone());
+    let state = base_state.clone_with(clone_config);
     if clone_config.committee_caches {
         state
             .committee_cache(RelativeEpoch::Previous)
@@ -260,6 +261,7 @@ fn tree_hash_cache() {
 mod committees {
     use super::*;
     use crate::beacon_state::MinimalEthSpec;
+    use std::ops::{Add, Div};
     use swap_or_not_shuffle::shuffle_list;
 
     fn execute_committee_consistency_test<T: EthSpec>(
@@ -295,7 +297,10 @@ mod committees {
             // of committees in an epoch.
             assert_eq!(
                 beacon_committees.len() as u64,
-                state.get_epoch_committee_count(relative_epoch).unwrap() / T::slots_per_epoch()
+                state
+                    .get_epoch_committee_count(relative_epoch)
+                    .unwrap()
+                    .div(T::slots_per_epoch())
             );
 
             for (committee_index, bc) in beacon_committees.iter().enumerate() {
@@ -372,10 +377,11 @@ mod committees {
     fn committee_consistency_test_suite<T: EthSpec>(cached_epoch: RelativeEpoch) {
         let spec = T::default_spec();
 
-        let validator_count = spec.max_committees_per_slot
-            * T::slots_per_epoch() as usize
-            * spec.target_committee_size
-            + 1;
+        let validator_count = spec
+            .max_committees_per_slot
+            .mul(T::slots_per_epoch() as usize)
+            .mul(spec.target_committee_size)
+            .add(1);
 
         committee_consistency_test::<T>(validator_count as usize, Epoch::new(0), cached_epoch);
 
@@ -387,7 +393,10 @@ mod committees {
 
         committee_consistency_test::<T>(
             validator_count as usize,
-            T::genesis_epoch() + T::slots_per_historical_root() as u64 * T::slots_per_epoch() * 4,
+            T::genesis_epoch()
+                + (T::slots_per_historical_root() as u64)
+                    .mul(T::slots_per_epoch())
+                    .mul(4),
             cached_epoch,
         );
     }

consensus/types/src/chain_spec.rs

@@ -405,6 +405,7 @@ mod tests {
         let _ = ChainSpec::mainnet();
     }
 
+    #[allow(clippy::useless_vec)]
     fn test_domain(domain_type: Domain, raw_domain: u32, spec: &ChainSpec) {
         let previous_version = [0, 0, 0, 1];
         let current_version = [0, 0, 0, 2];

consensus/types/src/tree_hash_impls.rs

@@ -137,9 +137,11 @@ mod test {
 
     #[test]
     fn zeroed_validator() {
-        let mut v = Validator::default();
-        v.activation_eligibility_epoch = Epoch::from(0u64);
-        v.activation_epoch = Epoch::from(0u64);
+        let v = Validator {
+            activation_eligibility_epoch: Epoch::from(0u64),
+            activation_epoch: Epoch::from(0u64),
+            ..Default::default()
+        };
         test_validator_tree_hash(&v);
     }
 
@@ -153,6 +155,7 @@ mod test {
     }
 
     #[test]
+    #[allow(clippy::assertions_on_constants)]
     pub fn smallvec_size_check() {
         // If this test fails we need to go and reassess the length of the `SmallVec` in
         // `cached_tree_hash::TreeHashCache`. If the size of the `SmallVec` is too slow we're going