Assert Mint Account

AssertMintAccount Instruction

The AssertMintAccount instruction is for making assertions on the fields of a spl-token mint account struct.

This could also be accomplished by using the AssertAccountData instruction, but this instruction is a convenience instruction for mint accounts which checks that the account is owned by the spl-token program and maps enums to offset / type deserialization.

Below are the types of assertions you can make about a mint account:

pub enum MintAccountAssertion {
    MintAuthority {
        value: Option<Pubkey>,
        operator: EquatableOperator,
    },
    Supply {
        value: u64,
        operator: IntegerOperator,
    },
    Decimals {
        value: u8,
        operator: IntegerOperator,
    },
    IsInitialized {
        value: bool,
        operator: EquatableOperator,
    },
    FreezeAuthority {
        value: Option<Pubkey>,
        operator: EquatableOperator,
    },
}

Example: showcase of the mint assertions.

Assuming there is a mint account that looks like the following

let mint = Mint {
    mint_authority: user_key,
    supply: 69_000,
    decimals: 9,
    is_initialized: true,
    freeze_authority: COption::None,
};

Then, the following assertions could be made about that account.

const tx = await pipe(
  createTransaction({ version: 0 }),
  (tx) =>
    appendTransactionInstructions(
      [
        getAssertTokenAccountMultiInstruction({
          targetAccount: mintKey,
          assertions: [
            mintAccountAssertion('MintAuthority', {
              value: userKey,
              operator: EquatableOperator.Equal,
            }),
            mintAccountAssertion('Supply', {
              value: 69_000,
              operator: IntegerOperator.Equal,
            }),
            mintAccountAssertion('Decimals', {
              value: 9,
              operator: IntegerOperator.Equal,
            }),
            mintAccountAssertion('IsInitialized', {
              value: true,
              operator: EquatableOperator.Equal,
            }),
            mintAccountAssertion('FreezeAuthority', {
              value: null,
              operator: EquatableOperator.Equal,
            }),
          ],
        }),
      ],
      tx
    ),
  (tx) => setTransactionFeePayer(userKey, tx),
  (tx) => setTransactionLifetimeUsingBlockhash(recentBlockhash, tx),
  (tx) => signTransaction([userKeyPair], tx)
)