Add chain_dump fn to beacon_chain

beacon_node/beacon_chain/tests/chain.rs

@@ -12,4 +12,7 @@ fn it_can_produce_blocks() {
     for _ in 0..blocks {
         rig.produce_next_slot();
     }
+    let dump = rig.chain_dump().expect("Chain dump failed.");
+
+    assert_eq!(dump.len(), blocks + 1); // + 1 for genesis block.
 }

beacon_node/beacon_chain/tests/utils/test_rig.rs

@@ -1,4 +1,5 @@
 use super::TestValidator;
+pub use beacon_chain::dump::{Error as DumpError, SlotDump};
 use beacon_chain::BeaconChain;
 #[cfg(test)]
 use db::{
@@ -82,4 +83,8 @@ impl TestRig {
         self.validators[proposer].set_slot(slot);
         self.validators[proposer].produce_block().unwrap();
     }
+
+    pub fn chain_dump(&self) -> Result<Vec<SlotDump>, DumpError> {
+        self.beacon_chain.chain_dump()
+    }
 }