Testnet about sparrow

[java4tech]

I think testnet could be a nice addition, it'll allow devs and non-devs to test features and also test edge cases without taking risk with bitcoin which they might be reluctant to use since this software is new in the market. Testnet allows real world testing on the public blockchain.

[craigraw]

No testnet support yet - may add in future depending on the need.

[sgeisler]

I think for integration testing at least having regtest support would be super useful. You could test the entire system (bitcoind, electrum server, sparrow) with custom scenarios fully automatically. I think there are even ui test libraries for Java, so you could emulate user behavior and test if everything works as intended automatically.

[djpnewton]

I agree testnet is necessary so we can test functionality without risking bitcoin

[craigraw]

Testnet has now been implemented over a series of recent commits, but mostly c68cda5 and ff7a35e.

See the notes at https://github.com/sparrowwallet/sparrow#configuration for running Sparrow on testnet.

Thanks to @djpnewton for the PR and discussion!