Staking extrinsics are no longer supported in dry run

[antlerminator]

Some time ago #1955 has removed support the dry run support for staking extrinsics. Before that PR, you were able to dry run them and get a proper validation errors. Now all dry run calls on staking extrinsics return "success" per this line:

subtensor/pallets/subtensor/src/transaction_extension.rs

Line 301 in 20cbabc

_ => Ok((Default::default(), Some(who.clone()), origin)),

[open-junius]

I checked the PR #1955, it just add the check for staking extrinsic if the coldkey in coldkey swap process. And later these checks are removed. The validation in transaction_extension is happened before extrinsic into mempool. It doesn't impact on dry run. I just tried in js code, it looks good. I can get the non-zero result if extrinsic is wrong.

const stake = api.tx.SubtensorModule.add_stake({ hotkey: convertPublicKeyToSs58(bob.publicKey), netuid: netuid, amount_staked: 10n });
    const txHex = await stake.sign(signer)
    const result = await client._request("system_dryRun", [txHex]);
    console.log('Dry Run Result:', result);

[antlerminator]

Heck, I linked wrong PR indeed.

I have no idea what changed but last week when I tried it I'm 100% sure that dry running wasn't working. No matter what I did the dry run was successful back then. I explicitly remember it cause I was quite flabbergasted when I saw add_stake transaction passing dry run when using netuid 999 and 10x my balance. I don't own an archive node so I cannot verify it again now.

I've tried it just now and seems to be working, however not in all cases correctly. Dry running remove_stake tx with correct hotkey and netuid but with amount way bigger than your current alpha balance results in passed dry run:

This means there's still a bug somewhere 🤔

After all those changes, where can I find the code that's responsible for dry running? For example previously validate_add_stake was called directly. How does it work exactly now?

[open-junius]

I will try remove_stake in my local for your case. validate_add_stake check is not for dry run. It will be called before transaction go to mempool.
In subtensor node, the system dryrun rpc is responsible for such request. Then the client call the runtime execute api.
the execution process is the same as normal extrinsic, but not change anything.

[open-junius]

It is not a bug. If the unstake_amount is larger than available, then we will use available alpha.

        let alpha_unstaked = alpha_unstaked.min(alpha_available);

[open-junius]

It will also pass the normal execution. You can try

[antlerminator]

Interesting. So I guess everything seems to be all good with dry run. I'm extremely curious what exactly has happened the last time I tried using it... Anyway, gonna close this issue!