Function resolve 

fn resolve(
    chain_id: u64,
    cache_dir: Option<&Path>,
    addresses: impl IntoIterator<Item = Address>,
    timeout: Duration,
    fetch_sources: impl FnOnce(&[Address], Duration) -> AddressMap<Option<Metadata>>,
) -> AddressMap<(String, Arc<StorageLayout>)>

fetch_external_storage_layouts with the cache location supplied, so tests can point it somewhere other than the user’s home directory.