I am in the process of testing out some Uniswap v3 libraries like https://github.com/uniswap-integration/simple-uniswap-sdk/ and would like to know how to find pool and token addresses for Uniswap v3 on the Ropsten network and eventually for the Optimism main and Kovan test networks.
I have been able to successfully get these mainnet values by querying the v3 subgraph. Are there subgraphs available for test networks or where can find the contract IDs?
The best way to go is actually do a swap in the Uniswap interface which also works with testnets, just add the tokens you would like to find the pool address for (probably with manual import), make a swap and notice the addresses on Etherscan from which the tokens are sent to you. This would be the pool address you are looking for.
To access testnet UI in case of Ropsten for example: https://app.uniswap.org/#/swap?chain=ropsten
Example transaction can be found here and the pool address is:
0xd2a6d30c2037390dc8e247d6b7e0ec11e3047499
(there is also a second pool involved in routing so you can find several pools if there are positions with different fee)