Python SDK - Simulating Transactions

Simulating transactions allows you to preview the cost and effect of submitting a transaction without paying fees. You can use this to estimate fees, test a transaction, or to check what the output might be.

To simulate a transaction, pass in a raw transaction and the sender’s public key:

import asyncio

from aptos_sdk.v2 import Account, Aptos, AptosConfig, Network
from aptos_sdk.v2.bcs import Serializer
from aptos_sdk.v2.transactions import EntryFunction, TransactionArgument, TransactionPayload
from aptos_sdk.v2.types import StructTag, TypeTag


async def main():
    async with Aptos(AptosConfig(network=Network.DEVNET)) as aptos:
        alice = Account.generate()
        bob = Account.generate()

        await aptos.faucet.fund_account(alice.address, 100_000_000)
        await aptos.faucet.fund_account(bob.address, 10_000_000)

        payload = EntryFunction.natural(
            "0x1::coin",
            "transfer",
            [TypeTag(StructTag.from_str("0x1::aptos_coin::AptosCoin"))],
            [
                TransactionArgument(bob.address, Serializer.struct),
                TransactionArgument(50_000, Serializer.u64),
            ],
        )
        raw_txn = await aptos.transaction.build(
            sender=alice.address,
            payload=TransactionPayload(payload),
        )

        simulation_result = await aptos.transaction.simulate(raw_txn, alice.public_key)
        print(f"Success: {simulation_result[0]['success']}")
        print(f"Gas used: {simulation_result[0]['gas_used']}")
        print(f"VM status: {simulation_result[0]['vm_status']}")


asyncio.run(main())

Look here to see the full example of how to build, simulate, and submit a transaction.

You can also learn how to simulate more advanced transactions by looking at the following guides:

• Sponsored Transactions
• Multi-Agent Transactions