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@topherPedersen
Last active Jan 15, 2022
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Solana 101: Hello, World Rust/Solana Program (from Figment.io's Solana 101 Course)
use borsh::{BorshDeserialize, BorshSerialize};
use solana_program::{
account_info::{next_account_info, AccountInfo},
entrypoint,
entrypoint::ProgramResult,
msg,
program_error::ProgramError,
pubkey::Pubkey,
};
/// Define the type of state stored in accounts
#[derive(BorshSerialize, BorshDeserialize, Debug)]
pub struct GreetingAccount {
/// number of greetings
pub counter: u32,
}
// Declare and export the program's entrypoint
entrypoint!(process_instruction);
// Program entrypoint's implementation
pub fn process_instruction(
program_id: &Pubkey, // Public key of the account the hello world program was loaded into
accounts: &[AccountInfo], // The account to say hello to
_instruction_data: &[u8], // Ignored, all helloworld instructions are hellos
) -> ProgramResult {
msg!("Hello World Rust program entrypoint");
// Iterating accounts is safer then indexing
let accounts_iter = &mut accounts.iter();
// Get the account to say hello to
let account = next_account_info(accounts_iter)?;
// The account must be owned by the program in order to modify its data
if account.owner != program_id {
msg!("Greeted account does not have the correct program id");
return Err(ProgramError::IncorrectProgramId);
}
// Increment and store the number of times the account has been greeted
let mut greeting_account = GreetingAccount::try_from_slice(&account.data.borrow())?;
greeting_account.counter += 1;
greeting_account.serialize(&mut &mut account.data.borrow_mut()[..])?;
msg!("Greeted {} time(s)!", greeting_account.counter);
Ok(())
}
// Sanity tests
#[cfg(test)]
mod test {
use super::*;
use solana_program::clock::Epoch;
use std::mem;
#[test]
fn test_sanity() {
let program_id = Pubkey::default();
let key = Pubkey::default();
let mut lamports = 0;
let mut data = vec![0; mem::size_of::<u32>()];
let owner = Pubkey::default();
let account = AccountInfo::new(
&key,
false,
true,
&mut lamports,
&mut data,
&owner,
false,
Epoch::default(),
);
let instruction_data: Vec<u8> = Vec::new();
let accounts = vec![account];
assert_eq!(
GreetingAccount::try_from_slice(&accounts[0].data.borrow())
.unwrap()
.counter,
0
);
process_instruction(&program_id, &accounts, &instruction_data).unwrap();
assert_eq!(
GreetingAccount::try_from_slice(&accounts[0].data.borrow())
.unwrap()
.counter,
1
);
process_instruction(&program_id, &accounts, &instruction_data).unwrap();
assert_eq!(
GreetingAccount::try_from_slice(&accounts[0].data.borrow())
.unwrap()
.counter,
2
);
}
}
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