Forge can capture gas snapshots over arbitrary sections inside of your test functions. This can be useful to get a granular measurement of how much gas your logic is consuming as both external calls and internal gas usage are measured.
Instead of running a command like forge snapshot or forge test --gas-report, you use the snapshotGas cheatcodes in your tests to capture gas usage as follows:
{{#include ../cheatcodes/gas-snapshots.md}}