使用模拟客户端

您可以使用模拟客户端来快速轻松地在本地测试您的交易，非常适合单元测试。为了开始，我们需要一个带有初始ETH的账户。为此，首先生成一个账户私钥。

privateKey, err := crypto.GenerateKey()
if err != nil {
  log.Fatal(err)
}

接着从accounts/abi/bind包创建一个NewKeyedTransactor，并为其传递私钥。

auth := bind.NewKeyedTransactor(privateKey)

下一步是创建一个创世账户并为其分配初始余额。我们将使用core包的GenesisAccount类型。

balance := new(big.Int)
balance.SetString("10000000000000000000", 10) // 10 eth in wei

address := auth.From
genesisAlloc := map[common.Address]core.GenesisAccount{
  address: {
    Balance: balance,
  },
}

现在我们将创世分配结构体和配置好的汽油上限传给account/abi/bind/backends包的NewSimulatedBackend方法，该方法将返回一个新的模拟以太坊客户端。

blockGasLimit := uint64(4712388)
client := backends.NewSimulatedBackend(genesisAlloc, blockGasLimit)

您可以像往常一样使用此客户端。作为一个示例，我们将构造一个新的交易并进行广播。

fromAddress := auth.From
nonce, err := client.PendingNonceAt(context.Background(), fromAddress)
if err != nil {
  log.Fatal(err)
}

value := big.NewInt(1000000000000000000) // in wei (1 eth)
gasLimit := uint64(21000)                // in units
gasPrice, err := client.SuggestGasPrice(context.Background())
if err != nil {
  log.Fatal(err)
}

toAddress := common.HexToAddress("0x4592d8f8d7b001e72cb26a73e4fa1806a51ac79d")
var data []byte
tx := types.NewTransaction(nonce, toAddress, value, gasLimit, gasPrice, data)
chainID := big.NewInt(1)
signedTx, err := types.SignTx(tx, types.NewEIP155Signer(chainID), privateKey)
if err != nil {
  log.Fatal(err)
}

err = client.SendTransaction(context.Background(), signedTx)
if err != nil {
  log.Fatal(err)
}

fmt.Printf("tx sent: %s\n", signedTx.Hash().Hex()) // tx sent: 0xec3ceb05642c61d33fa6c951b54080d1953ac8227be81e7b5e4e2cfed69eeb51

到现在为止，您可能想知道交易何时才会被开采。为了“开采”它，您还必须做一件额外的事情，在客户端调用Commit提交新开采的区块。

client.Commit()

现在您可以获取交易收据并看见其已被处理。

receipt, err := client.TransactionReceipt(context.Background(), signedTx.Hash())
if err != nil {
  log.Fatal(err)
}
if receipt == nil {
  log.Fatal("receipt is nil. Forgot to commit?")
}

fmt.Printf("status: %v\n", receipt.Status) // status: 1

因此，请记住：模拟客户端允许您使用模拟客户端的Commit方法手动开采区块。

完整代码

client_simulated.go

package main

import (
    "context"
    "fmt"
    "log"
    "math/big"

    "github.com/ethereum/go-ethereum/accounts/abi/bind"
    "github.com/ethereum/go-ethereum/accounts/abi/bind/backends"
    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/core"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/crypto"
)

func main() {
    privateKey, err := crypto.GenerateKey()
    if err != nil {
        log.Fatal(err)
    }

    auth := bind.NewKeyedTransactor(privateKey)

    balance := new(big.Int)
    balance.SetString("10000000000000000000", 10) // 10 eth in wei

    address := auth.From
    genesisAlloc := map[common.Address]core.GenesisAccount{
        address: {
            Balance: balance,
        },
    }

    blockGasLimit := uint64(4712388)
    client := backends.NewSimulatedBackend(genesisAlloc, blockGasLimit)

    fromAddress := auth.From
    nonce, err := client.PendingNonceAt(context.Background(), fromAddress)
    if err != nil {
        log.Fatal(err)
    }

    value := big.NewInt(1000000000000000000) // in wei (1 eth)
    gasLimit := uint64(21000)                // in units
    gasPrice, err := client.SuggestGasPrice(context.Background())
    if err != nil {
        log.Fatal(err)
    }

    toAddress := common.HexToAddress("0x4592d8f8d7b001e72cb26a73e4fa1806a51ac79d")
    var data []byte
    tx := types.NewTransaction(nonce, toAddress, value, gasLimit, gasPrice, data)

    chainID := big.NewInt(1)
    signedTx, err := types.SignTx(tx, types.NewEIP155Signer(chainID), privateKey)
    if err != nil {
        log.Fatal(err)
    }

    err = client.SendTransaction(context.Background(), signedTx)
    if err != nil {
        log.Fatal(err)
    }

    fmt.Printf("tx sent: %s\n", signedTx.Hash().Hex()) // tx sent: 0xec3ceb05642c61d33fa6c951b54080d1953ac8227be81e7b5e4e2cfed69eeb51

    client.Commit()

    receipt, err := client.TransactionReceipt(context.Background(), signedTx.Hash())
    if err != nil {
        log.Fatal(err)
    }
    if receipt == nil {
        log.Fatal("receipt is nil. Forgot to commit?")
    }

    fmt.Printf("status: %v\n", receipt.Status) // status: 1
}