以太坊常见问题和错误

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如何使用truffle来测试以太坊的时间日志Event logs?

例如我有一个智能合约函数,它在每次调用中触发事件。 我想在每次通过的测试中发送一个事件,下面是我的一些测试:

it("should emit Error event when sending 5 ether", function(done){
  var insurance = CarInsurance.deployed();

  insurance.send({from: accounts[0], value: web3.toWei(5, 'ether')}).then(done).catch(done);
});

it("should emit Error event when sending 5 ether", function(done){
  var insurance = CarInsurance.deployed();

  insurance.send({from: accounts[0], value: web3.toWei(5, 'ether')}).then(function(txHash){
    assert.notEqual(txHash, null);
  }).then(done).catch(done);
});

it("should emit Error event when sending 5 ether", function(done){
  var insurance = CarInsurance.deployed();

  insurance.send({from: accounts[0], value: web3.toWei(5, 'ether')}).then(function(done){
    done();
  }).catch(done);
});

但是运行结果是:

1) should emit Error event when sending 5 ether

Events emitted during test:
---------------------------

Error(error: Must send 10 ether)

---------------------------
✓ should emit Error event when sending 5 ether (11120ms)
✓ should emit Error event when sending 5 ether (16077ms)


3 passing (51s)
1 failing

1) Contract: CarInsurance should emit Error event when sending 5 ether:
 Error: done() invoked with non-Error: 0x87ae32b8d9f8f09dbb5d7b36267370f19d2bda90d3cf7608629cd5ec17658e9b
Yo

可以看到以一个失败记录。

问题出在哪儿?

你的代码正在将 tx hash 哈希传递到done()函数中。问题在这一行:

insurance.send({from: accounts[0], value: web3.toWei(5, 'ether')}).then(done).catch(done);

应该改成:

insurance.send({from: accounts[0], value: web3.toWei(5, 'ether')}).then(function() { done(); }).catch(done);

然后再去测试事件看看日志情况:

it("should check events", function(done) {
  var watcher = contract.Reward();

  // we'll send rewards
  contract.sendReward(1, 10000, {from: accounts[0]}).then(function() {
    return watcher.get();
  }).then(function(events) {
    // now we'll check that the events are correct
    assert.equal(events.length, 1);
    assert.equal(events[0].args.beneficiary.valueOf(), 1);
    assert.equal(events[0].args.value.valueOf(), 10000);
  }).then(done).catch(done);
});