Altair consensus changes and refactors (#2279)

## Proposed Changes

Implement the consensus changes necessary for the upcoming Altair hard fork.

## Additional Info

This is quite a heavy refactor, with pivotal types like the `BeaconState` and `BeaconBlock` changing from structs to enums. This ripples through the whole codebase with field accesses changing to methods, e.g. `state.slot` => `state.slot()`.


Co-authored-by: realbigsean <seananderson33@gmail.com>

testing/state_transition_vectors/src/main.rs

@@ -2,15 +2,21 @@
 mod macros;
 mod exit;
 
+use beacon_chain::{
+    store::StoreConfig,
+    test_utils::{BeaconChainHarness, EphemeralHarnessType},
+};
+use lazy_static::lazy_static;
 use ssz::Encode;
-use state_processing::test_utils::BlockProcessingBuilder;
 use std::env;
 use std::fs::{self, File};
 use std::io::Write;
 use std::path::{Path, PathBuf};
 use std::process::exit;
-use types::MainnetEthSpec;
-use types::{BeaconState, ChainSpec, EthSpec, SignedBeaconBlock};
+use types::{
+    test_utils::generate_deterministic_keypairs, BeaconState, EthSpec, Keypair, SignedBeaconBlock,
+};
+use types::{Hash256, MainnetEthSpec, Slot};
 
 type E = MainnetEthSpec;
 
@@ -19,6 +25,8 @@ pub const VALIDATOR_COUNT: usize = 64;
 /// The base output directory for test vectors.
 pub const BASE_VECTOR_DIR: &str = "vectors";
 
+pub const SLOT_OFFSET: u64 = 1;
+
 /// Writes all known test vectors to `CARGO_MANIFEST_DIR/vectors`.
 fn main() {
     match write_all_vectors() {
@@ -39,16 +47,36 @@ pub struct TestVector {
     pub error: Option<String>,
 }
 
-/// Gets a `BlockProcessingBuilder` to be used in testing.
-fn get_builder(
-    spec: &ChainSpec,
-    epoch_offset: u64,
-    num_validators: usize,
-) -> BlockProcessingBuilder<MainnetEthSpec> {
-    // Set the state and block to be in the last slot of the `epoch_offset`th epoch.
-    let last_slot_of_epoch = (MainnetEthSpec::genesis_epoch() + epoch_offset)
-        .end_slot(MainnetEthSpec::slots_per_epoch());
-    BlockProcessingBuilder::new(num_validators, last_slot_of_epoch, &spec).build_caches()
+lazy_static! {
+    /// A cached set of keys.
+    static ref KEYPAIRS: Vec<Keypair> = generate_deterministic_keypairs(VALIDATOR_COUNT);
+}
+
+fn get_harness<E: EthSpec>(
+    slot: Slot,
+    validator_count: usize,
+) -> BeaconChainHarness<EphemeralHarnessType<E>> {
+    let harness = BeaconChainHarness::new_with_store_config(
+        E::default(),
+        None,
+        KEYPAIRS[0..validator_count].to_vec(),
+        StoreConfig::default(),
+    );
+    let skip_to_slot = slot - SLOT_OFFSET;
+    if skip_to_slot > Slot::new(0) {
+        let state = harness.get_current_state();
+        harness.add_attested_blocks_at_slots(
+            state,
+            Hash256::zero(),
+            (skip_to_slot.as_u64()..slot.as_u64())
+                .map(Slot::new)
+                .collect::<Vec<_>>()
+                .as_slice(),
+            (0..validator_count).collect::<Vec<_>>().as_slice(),
+        );
+    }
+
+    harness
 }
 
 /// Writes all vectors to file.