Calculate class_commitment from proof

[notlesh]

This works around an issue introduced when Pathfinder removed class_commitment from its class proof.

The proofs we get back from Pathfinder (prior to v0.8 RPC) are in order. What that means is that the proof is a list of MPT nodes, ordered such that you can walk through the proof from top-to-bottom. This implies that the first node is always the root node, which is the same thing as the commitment. In other words, we can get the root/commitment by simply looking at the first node, and that's what this PR does.

Note, however, that this is redundant -- verify_proof() ultimately hashes the root node and compares that to class_commitment, which is exactly what this PR does. It would be just as good to make class_commitment an Option an only verify it then; but this PR at least makes the problem clear.

Type

• feature
• bugfix
• dev (no functional changes, no API changes)
• fmt (formatting, renaming)
• build
• docs
• testing

Description

Breaking changes?

• yes
• no