Why can't we print b256 or AssetID in RustSDK test cases

General
1

How do you print b256 in test cases? Tried logging in Sway too, doesn’t show anything.

use fuels::{prelude::*, types::ContractId};

abigen!(Contract(name="MyContract", abi="out/debug/test_asset-abi.json"));


#[tokio::test]
async fn test_harness() {
    // Test code here
    let (instance, _id) = get_contract_instance().await;

    let result = instance.methods().deposit().call().await.unwrap();
    let result2 = instance.methods().test_deposit_asset_id_same_generated().call().await.unwrap();
    println!("{result}",result);
    println!("{result2}",result);



}
 

async fn get_contract_instance() -> (MyContract<WalletUnlocked>, ContractId) {
    // Launch a local network and deploy the contract
    let wallets = launch_custom_provider_and_get_wallets(
        WalletsConfig::new(
            Some(3),             /* Three wallets */
            Some(1),             /* Single coin (UTXO) */
            Some(1_000_000_000), /* Amount per coin */
        ),
        None,
        None,
    )
    .await
    .unwrap();
 
    let wallet = wallets.get(0).unwrap().clone();
    
    let id = Contract::load_from(
        "./out/debug/test_asset.bin",
        LoadConfiguration::default(),
    )
    .unwrap()
    .deploy(&wallet, TxPolicies::default())
    .await
    .unwrap();
 
    let instance = MyContract::new(id.clone(), wallet);
 
    (instance, id.into())
}

Error:

error[E0277]: `FuelCallResponse<Bits256>` doesn't implement `std::fmt::Display`
  --> tests/harness.rs:13:15
   |
13 |     println!("{result}",result);
   |               ^^^^^^^^ `FuelCallResponse<Bits256>` cannot be formatted with the default formatter
   |
   = help: the trait `std::fmt::Display` is not implemented for `FuelCallResponse<Bits256>`
   = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
   = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0277]: `FuelCallResponse<Bits256>` doesn't implement `std::fmt::Display`
  --> tests/harness.rs:14:15
   |
14 |     println!("{result2}",result);
   |               ^^^^^^^^^ `FuelCallResponse<Bits256>` cannot be formatted with the default formatted
2

Because of the call response, you need to add .value at the end to retrieve the value. The documentation is slightly ambiguous in returning values.

    let result= instance.methods().deposit().call().await.unwrap().value;
    let result2 = instance.methods().test_deposit_asset_id_same_generated().call().await.unwrap().value;

The above snippet will fix the problem

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3

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