Signet is a new way to implement the Bitcoin testnet, it offers a stable centralized testnet that developers can easily use.

A Testnet is an alternative Bitcoin Blockchain that is mostly used by developers to test their code, test edge case transactions and other development related subjects, the testnet is currently 1412193 blocks long and takes about 2 days to fully sync.

This caused some conversation on the bitcoin-dev mailing list calling for a reset of the testnet to make it sync faster and use less disk data, while some developers called for this, others actually called for a larger blockchain compared to the mainnet to find size-related errors. Developers like Jimmy Song and Johnson lau called for the existence of two testnets, one small and one large.

Currently bitcoin’s testnet mining is done by mining the entire mempool in every block, this can be relatively annoying to anyone doing development that depends on a fee market like fee adjusting or transaction merging. Recently a developer called on the bitcoin-dev mailing list for the maxBlockWeight of Bitcoin’s testnet to be changed to something less than the entire mempool to help wallet developers in testing. This is a reasonable suggestion as some mainnet wallets have to deal with fee-related problems like stuck transactions and fee bumping. The suggestion is very early but looks promising, we’ll be watching the mailing list for any new updates.

One of the strangest peculiarities in the Bitcoin Testnet is the way it generates blocks, to make testing easier on the testnet there’s a special rule in the consensus that if a block isn’t mined in the last 20 minutes the next block is going to reset the difficulty to 1, for reference the current Bitcoin Mainnet difficulty is 5363678461481.