* For example, without this change, to run the TxQ tests, must specify
`--unittest=TxQ1,TxQ2` on the command line. With this change, can use
`--unittest=TxQ`, and both will be run.
* An exact match will prevent any further partial matching.
* This could have some side effects for different tests with a common
name beginning. For example, NFToken, NFTokenBurn, NFTokenDir. This
might be useful. If not, the shorter-named test(s) can be renamed. For
example, NFToken to NFTokens.
* Split the NFToken, NFTokenBurn, and Offer test classes. Potentially speeds
up parallel tests by a factor of 5.
Without the protocol amendment introduced by this commit, an NFT ID can
be reminted in this manner:
1. Alice creates an account and mints an NFT.
2. Alice burns the NFT with an `NFTokenBurn` transaction.
3. Alice deletes her account with an `AccountDelete` transaction.
4. Alice re-creates her account.
5. Alice mints an NFT with an `NFTokenMint` transaction with params:
`NFTokenTaxon` = 0, `Flags` = 9).
This will mint a NFT with the same `NFTokenID` as the one minted in step
1. The params that construct the NFT ID will cause a collision in
`NFTokenID` if their values are equal before and after the remint.
With the `fixNFTokenRemint` amendment, there is a new sequence number
construct which avoids this scenario:
- A new `AccountRoot` field, `FirstNFTSequence`, stays constant over
time.
- This field is set to the current account sequence when the account
issues their first NFT.
- Otherwise, it is not set.
- The sequence of a newly-minted NFT is computed by: `FirstNFTSequence +
MintedNFTokens`.
- `MintedNFTokens` is then incremented by 1 for each mint.
Furthermore, there is a new account deletion restriction:
- An account can only be deleted if `FirstNFTSequence + MintedNFTokens +
256` is less than the current ledger sequence.
- 256 was chosen because it already exists in the current account
deletion constraint.
Without this restriction, an NFT may still be remintable. Example
scenario:
1. Alice's account sequence is at 1.
2. Bob is Alice's authorized minter.
3. Bob mints 500 NFTs for Alice. The NFTs will have sequences 1-501, as
NFT sequence is computed by `FirstNFTokenSequence + MintedNFTokens`).
4. Alice deletes her account at ledger 257 (as required by the existing
`AccountDelete` amendment).
5. Alice re-creates her account at ledger 258.
6. Alice mints an NFT. `FirstNFTokenSequence` initializes to her account
sequence (258), and `MintedNFTokens` initializes as 0. This
newly-minted NFT would have a sequence number of 258, which is a
duplicate of what she issued through authorized minting before she
deleted her account.
---------
Signed-off-by: Shawn Xie <shawnxie920@gmail.com>
o Fixes an off-by-one when determining which NFTokenPage an
NFToken belongs on.
o Improves handling of packed sets of 32 NFTs with
identical low 96-bits.
o Fixes marker handling by the account_nfts RPC command.
o Tightens constraints of NFTokenPage invariant checks.
Adds unit tests to exercise the fixed cases as well as tests
for previously untested functionality.
