Allow test_harness to load validators from file.

eth2/types/src/beacon_state/builder.rs

@@ -33,7 +33,7 @@ impl BeaconStateBuilder {
         }
     }
 
-    /// Produce the first state of the Beacon Chain.
+    /// Process deposit objects.
     ///
     /// Spec v0.4.0
     pub fn process_initial_deposits(
@@ -48,19 +48,47 @@ impl BeaconStateBuilder {
 
         self.state.process_deposits(deposit_data, spec);
 
+        self.activate_genesis_validators(spec);
+
+        self.state.deposit_index = initial_validator_deposits.len() as u64;
+    }
+
+    fn activate_genesis_validators(&mut self, spec: &ChainSpec) {
         for validator_index in 0..self.state.validator_registry.len() {
             if self.state.get_effective_balance(validator_index, spec) >= spec.max_deposit_amount {
                 self.state.activate_validator(validator_index, true, spec);
             }
         }
-
-        self.state.deposit_index = initial_validator_deposits.len() as u64;
     }
 
-    /// Builds a `BeaconState` using the `BeaconState::genesis(..)` function.
+    /// Instantiate the validator registry from a YAML file.
     ///
-    /// Each validator is assigned a unique, randomly-generated keypair and all
-    /// proof-of-possessions are verified during genesis.
+    /// This skips a lot of signing and verification, useful for fast test setups.
+    ///
+    /// Spec v0.4.0
+    pub fn import_existing_validators(
+        &mut self,
+        validators: Vec<Validator>,
+        initial_balances: Vec<u64>,
+        deposit_index: u64,
+        spec: &ChainSpec,
+    ) {
+        self.state.validator_registry = validators;
+
+        assert_eq!(
+            self.state.validator_registry.len(),
+            initial_balances.len(),
+            "Not enough balances for validators"
+        );
+
+        self.state.validator_balances = initial_balances;
+
+        self.activate_genesis_validators(spec);
+
+        self.state.deposit_index = deposit_index;
+    }
+
+    /// Updates the final state variables and returns a fully built genesis state.
     ///
     /// Spec v0.4.0
     pub fn build(mut self, spec: &ChainSpec) -> Result<BeaconState, BeaconStateError> {

eth2/types/src/slot_epoch.rs

@@ -12,7 +12,7 @@ use crate::slot_height::SlotHeight;
 /// may lead to programming errors which are not detected by the compiler.
 use crate::test_utils::TestRandom;
 use rand::RngCore;
-use serde_derive::Serialize;
+use serde_derive::{Deserialize, Serialize};
 use slog;
 use ssz::{hash, ssz_encode, Decodable, DecodeError, Encodable, SszStream, TreeHash};
 use std::cmp::{Ord, Ordering};
@@ -21,10 +21,10 @@ use std::hash::{Hash, Hasher};
 use std::iter::Iterator;
 use std::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Rem, Sub, SubAssign};
 
-#[derive(Eq, Debug, Clone, Copy, Default, Serialize)]
+#[derive(Eq, Debug, Clone, Copy, Default, Serialize, Deserialize)]
 pub struct Slot(u64);
 
-#[derive(Eq, Debug, Clone, Copy, Default, Serialize)]
+#[derive(Eq, Debug, Clone, Copy, Default, Serialize, Deserialize)]
 pub struct Epoch(u64);
 
 impl_common!(Slot);

eth2/types/src/validator.rs

@@ -1,13 +1,13 @@
 use crate::{test_utils::TestRandom, Epoch, Hash256, PublicKey};
 use rand::RngCore;
-use serde_derive::Serialize;
+use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode, TreeHash};
 use test_random_derive::TestRandom;
 
 /// Information about a `BeaconChain` validator.
 ///
 /// Spec v0.4.0
-#[derive(Debug, Clone, PartialEq, Serialize, Encode, Decode, TestRandom, TreeHash)]
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Encode, Decode, TestRandom, TreeHash)]
 pub struct Validator {
     pub pubkey: PublicKey,
     pub withdrawal_credentials: Hash256,