There are a few layers of bullshit to this PR.
First, there is the fact that it adds a functional test gated on a new
config flag which is disabled by default, so it actually adds broken
code with no tests, waiting to ruin your day 520 PRs later when #21935
enables the broken test.
Second, the test appears to be superficially nonsensical because it
generates two transactions from different wallets and tries to compare
them for byte-for-byte equality, which doesn't make sense (at least)
because change outputs are randomly located...so something fishy is
going on.
Of course, in Elements the transactions are *not* equal half the time
because the outputs are permuted, which may have let me quickly figure
out the issue, except...
Third, there is a red herring of a bug where the two transactions have
slightly different feerates. This turns out to be caused by
CWallet::CalculateMaximumSignedTxSize using differently sized dummy
transactions depending on whether watchonly outputs are included (this
fact is conveniently disguised by #17211 slightly changing this logic;
this is an unmerged PR in Core that Elements has a backport of an old
version of). And the two wallets have different watchonly settings.
A sub-red-herring is the fact that this bug results in a discrepancy
of 0.25 vbytes, so it does not appear in Core but does appear in
Elements (there is a 3/16 probability that we should be so unlucky...
we are).
But this is all irrelevant, because...
Fourth, this test is actually super bullshit. The way it works is by
constructing a PSBT legitimately, saving this to disk, then re-"signs"
using the external signer interface by using a mock signer that
COMPLETELY REPLACES THE TRANSACTION UNDER CONSTRUCTION. So it doesn't
matter what the fee output looks like and it doesn't matter what the
order of the outputs. Core does not detect this malfeasance and
neither does Elements. For some reason, Core has a functional test
that explicitly checks that you can do this even though it is insane
and it is hard to think of non-malicious reasons to do it.
Fifth, while Elements fails to detect that its external signer is
actually changing the transaction out from under it, it DOES assume
that this won't happen. In CWallet::SignPSBT it blithely un-replaces
the transaction, which undermines the functional test.
Sixth, the original PR where this test was introduced has comments
locked, so anyone who spent six hours reverse-engineering this idiotic
broken test, and is still feeling charitable enough to discuss it with
the Core developors, can go pound sand.
Anyway, just disabled the broken test and move on with our lives.
Made some edits to rpc/client.cpp on the advice of test/functional/rpc_help.py
to make the "RPC conversion tables" consistent, but I have no idea what these
tables are or what they're for. I assume, given that nobody has noticed these
inconsistencies ever, that they're fine.
Had to change a test vector to match our test framework's different deterministic
keys (when I produced these during the 0.21 rebase I made new random keys rather
than converting the existing ones, it appears).
This PR eliminates "strange regtest=0 behavior" in a test which had forced
us to disable the test for Elements. Can re-enable now :)
I also removed the `chain_in_args` parameter to `TestNode`, which Steven added
in https://github.com/ElementsProject/elements/pull/533 (which itself replaces
unconditionally adding chain={} on the command-line, which was added in #458).
These were added in the 0.17 rebase to deal with the job of starting bitcoind,
which then did not support the `chain=` command-line arg as well as elementsd,
which back then required this command-line arg.
This was causing some issues with the "check -acceptnonstdtxn doesn't work on
mainnet" test because it would add -chain=elementsregtest to the command-line
of a daemon that was supposed to be connecting to mainnet/liquidv1. It is
possible to override this behavior, but since 0.20+ versions of elementsd and
bitcoind have essentially the same support for chain= options, it seemed
cleaner to just eliminate the diff.
This uses a regtest-only RPC which checks that the chain is literally
"regtest". Since regtest is disabled in Elements (we use elementsregtest)
I weakened the check for this to just check that the chain name has
"regtest" somewhere in it. Hopefully this isn't too magical.
