Benchmarking in a cusom pallet requires a storage put operation in Staking pallet

Question

Let's say I have a pallet_x. In this pallet i have an extrinsic where I get the active_era using the below code :

            Staking::<T>::active_era()
                          .map(|e| e.index)
                          .ok_or(Error::<T>::FailedToGetActiveEra)?

So when I write benchmark for this extrinsic it fails with this error FailedToGetActiveEra

My question now is how to insert value to ActiveEra storage in pallet_staking from pallet_x ?

Answer 1

You can do it the same way as in tests, by inserting storage items like @Purple_Turtle posted in the comment;

pallet_staking::ActiveEra::<T>::put(…)

One example would be from the nomination-pools benchmark where it fudges the staking stoarge.

Normally it is better to have pallets communicate with each other via traits, since otherwise storage invariants can get invalidated when pallet_x just modifies the storage of pallet_y without its knowledge. But if you only do it in testing/benchmarks, then its fine.

Since that type has private fields, you can hack around it by decoding it from its struct elements. It's not ideal, but better than having to go through an upstream change:

#[test]
fn hack() {
    use codec::{Encode, Decode};
    
    new_test_ext().execute_with(|| {
        let raw = (4 as sp_staking::EraIndex, Some(10u64)).encode();
        let info = pallet_staking::ActiveEraInfo::decode(&mut &raw[..]).unwrap();
        // Now you can put it into stoarge.
        pallet_staking::ActiveEra::<Test>::put(&info);
    });
}