Add untested minimum viable block processing

beacon_chain/chain/src/transition.rs

@@ -0,0 +1,29 @@
+use super::BeaconChain;
+use db::ClientDB;
+use state_transition::{extend_active_state, StateTransitionError};
+use types::{ActiveState, BeaconBlock, CrystallizedState, Hash256};
+
+impl<T> BeaconChain<T>
+where
+    T: ClientDB + Sized,
+{
+    pub(crate) fn transition_states(
+        &self,
+        act_state: &ActiveState,
+        cry_state: &CrystallizedState,
+        block: &BeaconBlock,
+        block_hash: &Hash256,
+    ) -> Result<(ActiveState, Option<CrystallizedState>), StateTransitionError> {
+        let state_recalc_distance = block
+            .slot
+            .checked_sub(cry_state.last_state_recalculation_slot)
+            .ok_or(StateTransitionError::BlockSlotBeforeRecalcSlot)?;
+
+        if state_recalc_distance >= u64::from(self.config.cycle_length) {
+            panic!("Not implemented!")
+        } else {
+            let new_act_state = extend_active_state(act_state, block, block_hash)?;
+            Ok((new_act_state, None))
+        }
+    }
+}