Problems in storing data in Solana Account

Question

I need help in storing data into an account. Here's what I've done so far.

Below is my 'process_instruction' entry point,

pub fn process_instruction(...) -> ProgramResult {

    let account_info_iter = &mut accounts.iter();
    // get account where we have to store state
    let states_account_info = next_account_info(account_info_iter)?;

    let xyz: u64 = 1234567;
    let counter_struct = Counter {
        data: xyz
    };
    counter_struct.serialize(&mut &mut states_account_info.data.borrow_mut()[..])?;

    Ok(())
}

Here's my Counter Struct

#[derive(BorshSerialize, BorshDeserialize, Debug)]
pub struct Counter {
    /// mappings of the keys
    pub data: u64,
}

And this is how, I create the account inside the test,

let state_account_pubkey = Pubkey::new_unique();
let mut program_test = ProgramTest::new(
    "solana_states_save_program",
    program_id,
    processor!(process_instruction),
);

program_test.add_account(
    state_account_pubkey, 
    Account {
        lamports: 5,
        owner: program_id,
        ..Account::default()
    },
);

But after executing the test, I get the following error, inside process_instruction() method (on counter_struct.serialize(...) statement),

thread 'main' panicked at 'called Result::unwrap() on an Err value: TransactionError(InstructionError(0, BorshIoError("Unknown")))'

Kindly help.

Answer 1

We also needed to add account data space when creating an Account in tests, which I was missing.

program_test.add_account(
    state_account_pubkey, 
    Account {
        lamports: 5,
        data: vec![0_u8; mem::size_of::<u32>()],
        owner: program_id,
        ..Account::default()
    },
);

Hope, it helps someone.