Paul Hauner a17f74896a Fix bad assumption when checking finalized descendant (#1629) ... ## Issue Addressed - Resolves #1616 ## Proposed Changes Fixes a bug where we are unable to read the finalized block from fork choice. ## Detail I had made an assumption that the finalized block always has a parent root of `None`: e5fc6bab48/consensus/fork_choice/src/fork_choice.rs (L749-L752) This was a faulty assumption, we don't set parent *roots* to `None`. Instead we *sometimes* set parent *indices* to `None`, depending if this pruning condition is satisfied: e5fc6bab48/consensus/proto_array/src/proto_array.rs (L229-L232) The bug manifested itself like this: 1. We attempt to get the finalized block from fork choice 1. We try to check that the block is descendant of the finalized block (note: they're the same block). 1. We expect the parent root to be `None`, but it's actually the parent root of the finalized root. 1. We therefore end up checking if the parent of the finalized root is a descendant of itself. (note: it's an *ancestor* not a *descendant*). 1. We therefore declare that the finalized block is not a descendant of (or eq to) the finalized block. Bad. ## Additional Info In reflection, I made a poor assumption in the quest to obtain a probably negligible performance gain. The performance gain wasn't worth the risk and we got burnt.		2020-09-18 05:14:31 +00:00
..
tests.rs	Fix bad assumption when checking finalized descendant (#1629)	2020-09-18 05:14:31 +00:00