松露測試：如何測試 SafeMath 庫是否溢出

如何通過松露測試來測試一個函式是否可以防止溢出？

contract SafeMath{    
   function add(uint256 a, uint256 b) internal pure returns (uint256) {
       uint256 c = a + b;
       assert(c >= a);
       return c;
   }
}

contract TestSafeMath{ 
   function test_add_10_and_max_should_return_err() {
         uint256 max = 2**256 - 1;
         uint256 expected = "revert overflow error";
         Assert.errorsEqual(SafeMathExt.add(10, max), expected, "Addition of 10 and max should revert");
   }
}

`TestSafeMath

1. test_add_max_and_10_should_return_err No events were emitted 1 failing`

我怎樣才能通過這個測試？

我實際上不知道您的程式碼如何編譯，這顯然是一個問題

uint256 expected = "revert overflow error";

並且assert 庫的errorsEqual方法需要兩個錯誤程式碼

無論如何，解決此問題的一種方法是嘗試進行原始呼叫以測試 VM 內部是否存在恢復狀態。如果呼叫已正確執行，則 call 方法將返回 true，否則返回 false。

pragma solidity ^0.4.19;

import "truffle/Assert.sol";
import "truffle/DeployedAddresses.sol";
import "../contracts/SafeMath.sol";

contract TestSafeMath {
 SafeMath instance;

 constructor() public {
   instance = SafeMath(DeployedAddresses.SafeMath());
 }

 function testAdd_10_and_max_should_return_err() public {
   uint256 max = 2**256 - 1;
   bool passed = address(instance).call(bytes4(keccak256("add(uint256,uint256)")), 10, max);

   Assert.isFalse(passed, "test should fail");
 }
 function testAdd_10_and_10_should_be_ok() public {
   uint256 value = 10;
   bool passed = address(instance).call(bytes4(keccak256("add(uint256,uint256)")), 10, value);

   Assert.isTrue(passed, "test should not fail");
   Assert.equal(instance.add(10, value), value + 10, "should be 20");
 }
}

要獲得實際值，您需要再次呼叫該方法，因為原始呼叫不會給您返回值（請參閱第二個測試方法）。

輸出

 TestSafeMath
   ✓ testAdd_10_and_max_should_return_err (53ms)
   ✓ testAdd_10_and_10_should_be_ok (66ms)


 2 passing (987ms)

引用自：https://ethereum.stackexchange.com/questions/49342