pub fn get_test_signed_transaction(
    sender: AccountAddress,
    sequence_number: u64,
    private_key: &Ed25519PrivateKey,
    public_key: Ed25519PublicKey,
    payload: Option<TransactionPayload>,
    expiration_timestamp_secs: u64,
    gas_unit_price: u64,
    gas_currency_code: String,
    max_gas_amount: Option<u64>
) -> SignedTransaction