Simulated Backend

Overview

The simulatedBackend allows you to run high-speed tests without launching a real blockchain network. It is fully integrated with the go-alchemy-sdk, enabling you to use the SDK's namespaces (Core, Transact, Nft, etc.) in an in-process, deterministic environment.

Capabilities

Using gas.NewSimulatedAlchemy(backend), you can interact with a simulated environment as if it were a real network:

• Contract Deployment: Deploy and interact with contracts.
• Transact: Send transactions and mine them on-demand.
• ERC20/ERC721/StableCoin: Full support for standard contract operations.

Limitations

Because the simulated backend runs in-process and does not have an HTTP JSON-RPC layer:

• RPC Methods: Any method that relies on provider.Send or direct rpc.Client calls (e.g., Core.GetBalance, Debug.Snapshot, batch.Batcher) is unsupported.
• HTTP/Transport: Custom http.RoundTripper configurations are not applicable.

Tutorial: Integration in Unit Tests

The following example demonstrates how to set up an in-process simulated.Backend to test your smart contract interactions, including deployment and transaction.

func TestMyContractInteraction(t *testing.T) {
	// 1. Setup funded simulated backend
	balance := new(big.Int).Mul(big.NewInt(1_000), big.NewInt(1_000_000_000_000_000_000)) // 1000 ETH
	initAddress := common.HexToAddress("0x...") // Your funded test address
	
	backend := simulated.NewBackend(gethTypes.GenesisAlloc{
		initAddress: {Balance: balance},
	})
	defer backend.Close() // Essential cleanup

	// 2. Initialize SimulatedAlchemy
	alchemy, err := gas.NewSimulatedAlchemy(backend)
	assert.NoError(t, err)

	// 3. Deploy a contract
	w, _ := wallet.New(initPrivateKey)
	w.Connect(alchemy.GetProvider())
	contractAddress, err := w.DeployContract(context.Background(), &artifacts.MyContractMetaData)
	assert.NoError(t, err)

	// 4. Transact with the contract
	data := myContract.PackStore(big.NewInt(42))
	receipt, err := w.ContractTransact(context.Background(), contractAddress.Hex(), data)
	assert.NoError(t, err)
	assert.Equal(t, uint64(1), receipt.Status)
}

For more comprehensive usage, refer to the examples in e2e/simulated_test.go.