test.rs

#[tokio::test]
fn should_read_state() {
  // given
  
  // This starts a special "test node" in the background. We communicate with the node over RPC.
  let mut test = test::deterministic(PolkadotRuntime.into());
  type Balances = pallet_balances::Module<Runtime>;

  // This uses ManualSeal consensus (might require conditional compilation of Runtime though :()
  test.produce_blocks(1);

  // This is something we want to hide away / simplify
  let alice = sr25519::Pair::from_string("//Alice".into(), None).unwrap();
  let bob = sr25519::Pair::from_string("//Bob".into(), None).unwrap();
  let signer = PairSigner::new(alice.clone());
	
  // This runs within current-state context. Allows you to query storage items directly or call Module functions.
  let alice_balance = test.with_state(|| Balances::free_balance(MultiSigner::from(alice.public()).into_account())));
	
  // RPC client with pallet-specific extensions. Creates and sends a transaction.
  let client = test.rpc_client();
  client
    .transfer(&signer, &Address::from(MultiSigner::from(bob.public()).into_account()), 8900000000000000)
    .await
    .expect("failed to transfer funds");
        
  // Produce blocks (assuming the transaction is included)
  test.produce_blocks(1);

  // Read the state again to check that the balances has changed.
  let new_alice_balance = test.with_state(|| Balances::free_balance(MultiSigner::from(alice.public()).into_account()));
	
  // account for fees
  assert!((alice_balance - new_alice_balance) > 8900000000000000);
}