Macro assert_is_zero_token_account 

macro_rules! assert_is_zero_token_account {
    ($token_account: expr $(,)?) => { ... };
    ($token_account: expr, $err_code: ident $(,)?) => { ... };
    ($token_account: expr, $msg: literal $(,)?) => { ... };
    ($token_account: expr, $err: expr $(,)?) => { ... };
    ($token_account: expr, $err: expr, $msg: expr $(,)?) => { ... };
}

Asserts that a token account is “zero”.

This means that:

• the amount is zero
• the delegate is None
• the close_authority is None

This is useful for checking to see that a bad actor cannot modify PDA-owned token accounts.

Example

#[error_code]
pub enum ErrorCode { MyError }


let mut zero_account = spl_token::state::Account::default();
assert_does_not_throw!({
  assert_is_zero_token_account!(zero_account);
});

let mut non_zero_account = spl_token::state::Account::default();
non_zero_account.amount = 10;
assert_throws!({
  assert_is_zero_token_account!(non_zero_account);
}, tensor_vipers::VipersError::TokenAccountIsNonZero);

non_zero_account = spl_token::state::Account::default();
non_zero_account.delegate = spl_token::ID.into();
assert_throws!({
  assert_is_zero_token_account!(non_zero_account);
}, tensor_vipers::VipersError::TokenAccountIsNonZero);

non_zero_account = spl_token::state::Account::default();
non_zero_account.close_authority = spl_token::ID.into();
assert_throws!({
  assert_is_zero_token_account!(non_zero_account);
}, tensor_vipers::VipersError::TokenAccountIsNonZero);