Investigate inconsistent ssz deserialize

[twoeths]

Describe the bug

Given this block 32768 in oonoonba network
signed_block_32768.zip

const signedBlock = ssz.altair.SignedBeaconBlock.createTreeBackedFromBytes(signedBlockBuf);
console.log("@@@ loaded signed block successfully at slot", signedBlock.message.slot, "root", toHexString(ssz.altair.BeaconBlock.hashTreeRoot(signedBlock.message)));

gives us @@@ loaded signed block successfully at slot 32768 root 0xc1ad6fc70d6c83cba35288fc58441325bbb985b16b407bdff2857ba6a30fafd0 which is correct (since we can process that block)

while

const signedBlock = ssz.altair.SignedBeaconBlock.deserialize(signedBlockBuf);
console.log("@@@ loaded signed block successfully at slot", signedBlock.message.slot, "root", toHexString(ssz.altair.BeaconBlock.hashTreeRoot(signedBlock.message)));

gives us @@@ loaded signed block successfully at slot 32768 root 0x9b1482b3be4086d530feb8954f6b5a3a975381c26d2a97482f51db974b5fd59a

this is incorrect block root and we got Invalid block signature processing that block

Expected behavior

• ssz.altair.SignedBeaconBlock.deserialize() should be the same to ssz.altair.SignedBeaconBlock.createTreeBackedFromBytes()
• Need to investigate what caused the issue at ssz level

[twoeths]

• there is no issue with equal, it's just issue with hashTreeRoot
• hashTreeRoot(signedBlockStruct.message.body.syncAggregate.syncCommitteeBits) turns out to be incorrect

Note that BitVectorType is a new type in altair, that's why we haven't seen the issue during phase0 sync.

[dapplion]

• there is no issue with equal, it's just issue with hashTreeRoot
• hashTreeRoot(signedBlockStruct.message.body.syncAggregate.syncCommitteeBits) turns out to be incorrect

Note that BitVectorType is a new type in altair, that's why we haven't seen the issue during phase0 sync.

Should we add unit tests for that type in the ssz repo?

[twoeths]

we haven't implemented ssz spec tests, that should scan these ssz issues if we test both struct type and tree backed type

[dapplion]

we haven't implemented ssz spec tests, that should scan these ssz issues if we test both struct type and tree backed type

Should we prioritize implementing those then?

[twoeths]

Fixed in ssz 0.8.8