Download bitcoin core if you haven't already and run it using `
-regtest` then use the
generatetoaddress command to generate as many blocks as you want (generate at least 101 blocks so that the reward of first block is mature enough to spend) and then use the "unlimited" number of coins you have at your disposal to do any tests you want.
Mining 100 blocks on regtest takes a second because of the low difficulty that never changes.
generatetoaddress <number of blocks> <youraddress>
https://developer.bitcoin.org/examples/testing.html#regtest-modehttps://gist.github.com/System-Glitch/cb4e87bf1ae3fec9925725bb3ebe223a