使用 mocha.js 和 truffle 發送乙太幣可能會導致比預期更大的金額

再會，

我有一個契約 General 和一個圖書館 GenLib。

library GenLib{
   event MoneyIn (address _from, uint256 _amount);
   function moneyIn() {
      MoneyIn(msg.sender, msg.value); <- Only call the event MoneyIn()
  } 
}

contract General{
   function getMoney () payable{
       GenLib.moneyIn();
  }
}

現在奇怪的是，當我嘗試使用該getMoney函式向 General 合約匯款時，實際轉賬的金額是指定金額的兩倍。

那是我用來檢查契約的 JS 文件：

var Gen   = artifacts.require("General");

contract('Gen', function(accounts) {

 var user = accounts[0];

 var valueP2C      = web3.toWei(2, "ether");

 it("Deploy Gen contract", function(){
   return Gen.deployed().then(function(instance){
     gen = instance;
   });
 });

 it("Gen account is empty", function(done){
   web3.eth.getBalance(gen.address, function(err, res){
     done(assert.equal(res.valueOf(), 0, ""));
   });
 });

 it("Use account is full", function(done){
   web3.eth.getBalance(user, function(err, res){
     userAmount = res.valueOf(); 
     done(assert.equal(res.valueOf(), 0, ""));
   });
 });  

 it ("Send money from user to gen", function(done){ 
   gen.getMoney({from: user, value: valueP2C}).then(function(res){
       done(assert.notEqual(res, null, ""));
     });
 });


 it("Gen recieved money", function(done){
   web3.eth.getBalance(gen.address, function(err, res){
     done(assert.equal(res.valueOf(), valueP2C, ""));
   });
 });

 it("User account is P2C lower", function(done){
   web3.eth.getBalance(user, function(err, res){
     done(assert.equal(res.valueOf(), userAmount - valueP2C, ""));
   });
 });  
}); 

以及最終結果：

✓ Deploy Gen contract
✓ Gen account is empty
✓ User account is full
✓ Send money from user to gen
1) Gen received money
> No events were emitted
2) User account is P2C lower
> No events were emitted


expected '4000000000000000000' to equal '2000000000000000000' <-TWICE THE AMOUNT
expected '87641250800000000000' to equal 89643554700000000000

另一條可能有用的資訊是，每當我刪除對外部庫的呼叫時，一切正常。

我對這種奇怪的行為感到困惑，如果您能提供任何幫助或見解，我將不勝感激。

你感到困惑是對的——你觀察到的行為是錯誤的。

這是 testrpc 的一個未解決問題，正如您所說，它與庫函式的呼叫有關： https ://github.com/ethereumjs/testrpc/issues/122

抱歉，我無法提供更多幫助 - 您可以密切關注該問題何時正式修復！

它已在最新的4.1.0 版本中修復

引用自：https://ethereum.stackexchange.com/questions/15549