Extend BeaconChain persistence testing

eth2/lmd_ghost/src/lib.rs

@@ -8,7 +8,9 @@ pub use reduced_tree::ThreadSafeReducedTree;
 
 pub type Result<T> = std::result::Result<T, String>;
 
-pub trait LmdGhost<S: Store, E: EthSpec>: Send + Sync + Sized {
+// Note: the `PartialEq` bound is only required for testing. If it becomes a serious annoyance we
+// can remove it.
+pub trait LmdGhost<S: Store, E: EthSpec>: PartialEq + Send + Sync + Sized {
     /// Create a new instance, with the given `store` and `finalized_root`.
     fn new(store: Arc<S>, finalized_block: &BeaconBlock<E>, finalized_root: Hash256) -> Self;
 

eth2/lmd_ghost/src/reduced_tree.rs

@@ -55,6 +55,13 @@ impl<T, E> fmt::Debug for ThreadSafeReducedTree<T, E> {
     }
 }
 
+impl<T, E> PartialEq for ThreadSafeReducedTree<T, E> {
+    /// This implementation ignores the `store`.
+    fn eq(&self, other: &Self) -> bool {
+        *self.core.read() == *other.core.read()
+    }
+}
+
 impl<T, E> LmdGhost<T, E> for ThreadSafeReducedTree<T, E>
 where
     T: Store,
@@ -200,6 +207,15 @@ impl<T, E> fmt::Debug for ReducedTree<T, E> {
     }
 }
 
+impl<T, E> PartialEq for ReducedTree<T, E> {
+    /// This implementation ignores the `store` field.
+    fn eq(&self, other: &Self) -> bool {
+        self.nodes == other.nodes
+            && self.latest_votes == other.latest_votes
+            && self.root == other.root
+    }
+}
+
 impl<T, E> ReducedTree<T, E>
 where
     T: Store,
@@ -918,7 +934,7 @@ pub struct Vote {
 ///
 /// E.g., a `get` or `insert` to an out-of-bounds element will cause the Vec to grow (using
 /// Default) to the smallest size required to fulfill the request.
-#[derive(Default, Clone, Debug)]
+#[derive(Default, Clone, Debug, PartialEq)]
 pub struct ElasticList<T>(Vec<T>);
 
 impl<T> ElasticList<T>