关于 5.4.3 第二节 投票智能合约测试 的问题

[xu-kai-xu]

it("throws an exception for invalid candidates", function() {
    return Election.deployed().then(function(instance) {
      electionInstance = instance;
      return electionInstance.vote(99, { from: accounts[1] })
    }).then(assert.fail).catch(function(error) {
      assert(error.message.indexOf('revert') >= 0, "error message must contain revert");
      return electionInstance.candidates(1);
    }).then(function(candidate1) {
      var voteCount = candidate1[2];
      assert.equal(voteCount, 1, "Eric did not receive any votes");
      return electionInstance.candidates(2);
    }).then(function(candidate2) {
      var voteCount = candidate2[2];
      assert.equal(voteCount, 0, "Helen did not receive any votes");
      return electionInstance.candidates(3);
    }).then(function(candidate3) {
      var voteCount = candidate3[2];
      assert.equal(voteCount, 0, "Elena did not receive any votes");
    });
  });

问题：以上这段代码中，Eric 对应的 voteCount 是 1，为什么 也是 "Eric did not receive any votes"，是否应为，Eric has received one vote.

[xu-kai-xu]

同样是这一节，还有一个问题。

第五个用于测试一个选民多次投票的情况，仓库中提供的原始代码为

it("throws an exception for double voting", function() {
    return Election.deployed().then(function(instance) {
      electionInstance = instance;
      candidateId = 2;
      electionInstance.vote(candidateId, { from: accounts[1] });
      return electionInstance.candidates(candidateId);
    }).then(function(candidate) {
      var voteCount = candidate[2];
      assert.equal(voteCount, 1, "accepts first vote");
      // 重复投票
      return electionInstance.vote(candidateId, { from: accounts[1] });
    }).then(assert.fail).catch(function(error) {
      assert(error.message.indexOf('revert') >= 0, "error message must contain revert");
      return electionInstance.candidates(1);
    }).then(function(candidate1) {
      var voteCount = candidate1[2];
      assert.equal(voteCount, 1, "Eric did not receive any votes");
      return electionInstance.candidates(2);
    }).then(function(candidate2) {
      var voteCount = candidate2[2];
      assert.equal(voteCount, 1, "Helen did not receive any votes");
      return electionInstance.candidates(3);
    }).then(function(candidate3) {
      var voteCount = candidate3[2];
      assert.equal(voteCount, 0, "Elena did not receive any votes");
    });
  });

按照仓库中的代码敲进去后发现执行不通，然后花了两天时间尝试各种办法，最后无意间发现

it("throws an exception for double voting", function() {
    return Election.deployed().then(function(instance) {
      electionInstance = instance;
      candidateId = 2;
      electionInstance.vote(candidateId, { from: accounts[1] });
      return electionInstance.candidates(candidateId);
    }).then(function(candidate) {
      var voteCount = candidate[2];
      assert.equal(voteCount, 1, "accepts first vote");

这段代码的断言本身就通不过，所以推测是投票代码的问题，然后结合第二个测试中投票成功的例子

  it("allows a voter to cast a vote", function() {
      return Election.deployed().then(function(instance) {
        electionInstance = instance;
        candidateId = 1;
        return electionInstance.vote(candidateId, { from: accounts[0] });
      }).then(function(receipt) {
        return electionInstance.voters(accounts[0]);
      }).then(function(voted) {
        assert(voted, "the voter was marked as voted");
        return electionInstance.candidates(candidateId);
      }).then(function(candidate) {
        var voteCount = candidate[2];
        assert.equal(voteCount, 1, "increments the candidate's vote count");
      })
    });

对第五个测试的代码进行修改，发现原来的第五个测试少写了

 return electionInstance.vote(candidateId, {from: accounts[1]});
        }).then(function(receipt){
            return electionInstance.voters(accounts[1]);
        }).then(function(voted) {
            assert(voted, "the voter was marked as voted");
            return electionInstance.candidates(candidateId);

这段命令。根据我的理解，这段命令做的事情包括将投票人标记为已投票状态，这是用于判断非法投票的关键，加上这段后，第五个测试就可以通过。完整的修改后的第五个测试如下

    it("throws an exception for double voting", function() {
        return Election.deployed().then(function(instance) {
            electionInstance = instance;
            candidateId = 2;
            return electionInstance.vote(candidateId, {from: accounts[1]});
        }).then(function(voted) {
            assert(voted, "the voter was marked as voted");
            return electionInstance.candidates(candidateId);
        }).then(function(candidate) {
            var voteCount = candidate[2];
            assert.equal(voteCount, 1, 'mike accepts first vote');

            //重复投票
            return electionInstance.vote(candidateId, { from: accounts[1] });
        }).then(assert.fail).catch(function(error) {
            assert(error.message.indexOf('revert') >= 0, "error message must contain revert");
            return electionInstance.candidates(1);
        }).then(function(candidate1) {
            var voteCount = candidate1[2];
            assert.equal(voteCount, 1, "Eric did not receive any votes");
            return electionInstance.candidates(2);
        }).then(function(candidate2) {
            var voteCount = candidate2[2];
            assert.equal(voteCount, 1, "Mike did not receive any votes");
            return electionInstance.candidates(3);
        }).then(function(candidate3) {
            var voteCount = candidate3[2];
            assert.equal(voteCount, 0, "Elena did not receive any votes");
        });
    });

测试通过，nice。