foundry-mainnet-fork-etch-testing

You can test new logic against live mainnet state by forking mainnet and using vm.etch to replace runtime code while preserving on-chain storage. This allows you to validate deployed contract behavior without redeploying.

Yes, vm.etch replaces runtime code while keeping storage intact in a Foundry mainnet fork. You must ensure storage layout compatibility before applying etches to successfully validate new logic and migrations.

The best way to replay real interactions is by forking mainnet to create a live-like testing environment. This approach lets you verify contract behavior under realistic conditions without altering the original chain.

Use vm.etch when you need to validate deployed contract behavior against live data, replay real interactions, or test new logic against a mainnet mirror. It is essential for migrations where preserving on-chain state is required.

Yes, Foundry forking supports replacing runtime code via vm.etch. This combination enables end-to-end mainnet-like testing by selectively etching new logic while preserving the existing on-chain state for migration validation.

Verifying storage layout compatibility before etching runtime code is required because vm.etch replaces runtime code while preserving storage. Incompatible layouts will corrupt state interpretation and cause migration validation failures.