fn fake_sha256(data: &[u8]) -> H256 {
        use std::{collections::hash_map::DefaultHasher, hash::Hasher};

        let mut hasher = DefaultHasher::new();
        hasher.write(data);
        let result = hasher.finish();
        H256::from_low_u64_ne(result)
    }
A fake `sha256` hasher, which calculates an `std::hash` instead.
This is done for simplicity, and it's also much faster.
core/lib/eth_client/src/clients/mock.rs