# Fixtures

Runtime bytecode of two wETH implementations on the allowlist, pulled straight
off mainnets so the tests exercise real code rather than a mock that resembles
it. `vm.etch` puts one of these at an address and its `EXTCODEHASH` is then, by
construction, the value `WETHRegistry` is looking for — which is the only way
to test the allowlist without weakening it for tests.

| file | source | bytes | codehash |
| --- | --- | --- | --- |
| `weth9-op-legacy.hex` | Base, `0x4200000000000000000000000000000000000006` | 2041 | `0x8a3a1f6a9f9dce633117adee5b458245835a8645a8c8726a26382a4622508b1c` |
| `weth9-canonical.hex` | Ethereum, `0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2` | 3124 | `0xd0a06b12ac47863b5c7be4185c2deaad1c61557033f56c7d4ea74429cbb25e23` |

Refetch either with:

```shell
cast code 0x4200000000000000000000000000000000000006 --rpc-url https://base-rpc.publicnode.com
```

Both hashes appear in `script/weth-codehashes.sh` output and in the allowlist in
`src/WETHRegistry.sol`, so a fixture that has drifted shows up as a test
failure rather than as a silent pass.