How do you geeks use ic-agent in rust for testing?

I encounter some issue when using rust crate ic-agent.
And got no clue how to fix some little problems.
Can anyone share some use example of using ic-agent to test functions ?

use candid::Decode;
use candid::Principal;
async fn test1() {
  // Import the ic-agent crate and the candid crate
  use candid::{CandidType, Decode, Encode};
  use ic_agent::Agent;

  // Define a struct that corresponds to the Candid record type of the add_wallet argument
  struct AddWalletArgument {
    address: String,
    name: String,
    from: String,
  // ! simulate call from rust code :  dfx canister call backend add_wallet '(record { address = "a1"; name = "AmydaLu"; from = "asdaw" })'
  // Create an instance of the Agent struct
  let agent = Agent::builder()
    // Use the URL of the Internet Computer or a local replica
    // ! pgrep replica  # get pid from name
    // !  lsof -i -P -n | grep LISTEN | grep <pid>
    //  todo ! which port should i use ?
    // Use an identity to sign messages
    // todo: how to simulate : dfx use btwl1 ? and the account have passwd. when i exec dfx cmd . it requires my passwd in bash

  // Fetch the root key of the replica

  use backend::common::constants;
  // Get the canister identifier of the backend canister
  let backend_canister_id = Principal::from_text(constants::BACKEND_CANISTER_ID.to_string())?;
  let test_addr="67cff347f803890e6bd1865b5a116c8c06384992b93d2fc8bb8da2f22fffc6a3".to_string();

  // Create a Candid value that represents the argument of the add_wallet method
  let argument = Encode!(&AddWalletArgument {
    address: test_addr,
    name: "AmydaLu_wallet".to_string(),
    from: "nns".to_string(),

  // Call the add_wallet method on the backend canister
  let response = agent
    .update(&backend_canister_id, "add_wallet")
    // Pass the Candid value as the argument of the add_wallet method
    // Wait for the result of the update call

  // Decode the result of the update call

  let result = Decode!(response.as_slice(), Result<bool, String>)?;

  match result {
    Ok(_) => println!("Wallet added successfully"),
    Err(msg) => println!("Error: {}", msg),
  // Print the result
  println!("{:?}", result);

You will probably have a better time if you use pocket-ic for testing your canister in this way. You can use Rust or Python or TypeScript.