Test the getblocktemplate RPC's response as a block template proposal in CI

[arya2]

Motivation

The acceptance test could confirm that the getblocktemplate response in 'template' mode will be accepted if it has a valid solution by submitting the same data to the getblocktemplate method in 'proposal' mode.

Design

In the acceptance test that syncs until the tip and calls the getblocktemplate RPC method:

• Deserialize the response
• Convert the template into a block with empty solution and nonce fields
• Hex-encode the resulting block
• Call getblocktemplate in 'proposal' mode
• Assert a "null" response indicating successful validation (similar to the submitblock test)

[teor2345]

The acceptance test could confirm that the getblocktemplate response in 'template' mode will be accepted if it has a valid solution by submitting the same data to the getblocktemplate method in 'proposal' mode.

I'm not quite sure how this would work, do we need to mine a valid solution for the proposal to be valid?
Could we use submitblock in the test, rather than adding an extra unused proposal mode to getblocktemplate?

[arya2]

I'm not quite sure how this would work, do we need to mine a valid solution for the proposal to be valid? Could we use submitblock in the test, rather than adding an extra unused proposal mode to getblocktemplate?

It doesn't need a valid solution (it doesn't commit the block, just checks that it would be accepted if submitted with a valid solution), so a new block verifier request would skip the check::equihash_solution_is_valid(&block.header) here and use a CheckContextualValidity request instead of CommitBlock. Then if miners want to modify the template and then check that their modifications are still valid before mining, they could propose the new template.

The block data MUST be validated and checked against the server's usual acceptance rules (excluding the check for a valid proof-of-work) - https://en.bitcoin.it/wiki/BIP_0023#Block_Proposal

[teor2345]

Sounds good, can you update the ticket description with the spec details and your suggested design?

Sometimes they get lost in the comments!

[mpguerra]

I don't think we should do this in CI until we can confirm it manually

[mpguerra]

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