scaffold-eth 挑战：测试覆盖率（Part3）

我知道，你想直接部署合约和前端，并立刻就开始在测试网上进行测试，但是......我们需要确定一切都按预期工作，而不需要在前端用户界面（UI） 上进行 monkey 测试。

因此，在文章的下一部分，我将介绍一些开发人员应该做的事情：测试合约逻辑!

Waffle

Waffle是一个用于编写和测试智能合约的库，它与 ethers-js 配合得非常默契。

Waffle 有很多有帮助的工具。waffle 中的测试是用Mocha和Chai一起编写的。你可以使用不同的测试环境，但 Waffle 的匹配器(matcher)只能在chai下工作。

我们将使用Chai 匹配器来验证我们所期望的条件是否已经满足。

在写完所有的测试用例后，你只需要输入yarn test，就会自动针对你的合约进行测试。

我不会解释如何使用这个库（你可以简单地看一下下面的代码来了解），我将专注于应该测试什么。

我们的合约已经实现了一些逻辑：

• 用mapping(address => uint256) public balances保存用户余额
• 有一个最小质押金额的阀值uint256 public constant threshold = 1 ether。
• 有一个最大的时间限制(deadline) uint256 public deadline = block.timestamp + 120 seconds。
• 如果外部合约不是 completed并且 deadline 还没有到，用户可以调用stake()函数
• 如果外部合约不是 completed并且 deadline 还没有到，用户可以调用 execute方法。
• 如果时间已经到了 deadline 并且外部合约不是 completed，用户可以撤回资金。
• timeLeft()返回剩余的秒数，直到时间到deadline，之后它应该总是返回0

测试中应该涵盖什么

PS: 这是我个人的测试方法，如果你有建议，请在 Twitter 上找我!

我写测试的时候，习惯用一个独立的函数并且覆盖所有边缘情况。试试写一写测试用例来回答下面的问题：

• 是否已经涵盖所有边缘情况？
• 函数是否按预期回退？
• 函数是否按需发出事件？
• 输入特殊值时，函数是否输出预期结果？是否按预期达到新状态？
• 函数是否按预期返回值（如果它有返回）？

如何在测试中模拟挖矿

还记得我们说过吗，为了正确模拟 timeLeft()，我们必须创建交易或从水龙头（Faucet）获取资金（这也是一种交易）。好吧，为了解决这个问题，我写了一个小程序（你可以直接复制到其他项目中）。

当你调用increaseWorldTimeInSeconds(10, true)时，EVM 内部时间戳会比当前时间快进10秒。之后，如果指定出块，它还会挖一个块来创建一个交易。

下次合约被调用时，timeLeft()应该被更新。

测试execute()函数

我们先看这一部分测试，然后我将发布整段代码，我只解释其中一些特定的代码。这段代码涵盖了 execute() 函数：

describe('Test execute() method', () => {
    it('execute reverted because stake amount not reached threshold', async () => {
      await expect(stakerContract.connect(addr1).execute()).to.be.revertedWith('Threshold not reached');
    });

    it('execute reverted because external contract already completed', async () => {
      const amount = ethers.utils.parseEther('1');
      await stakerContract.connect(addr1).stake({
        value: amount,
      });
      await stakerContract.connect(addr1).execute();

      await expect(stakerContract.connect(addr1).execute()).to.be.revertedWith('staking process already completed');
    });

    it('execute reverted because deadline is reached', async () => {
      // reach the deadline
      await increaseWorldTimeInSeconds(180, true);

      await expect(stakerContract.connect(addr1).execute()).to.be.revertedWith('Deadline is already reached');
    });

    it('external contract sucessfully completed', async () => {
      const amount = ethers.utils.parseEther('1');
      await stakerContract.connect(addr1).stake({
        value: amount,
      });
      await stakerContract.connect(addr1).execute();

      // check that the external contract is completed
      const completed = await exampleExternalContract.completed();
      expect(completed).to.equal(true);

      // check that the external contract has the staked amount in it's balance
      const externalContractBalance = await ethers.provider.getBalance(exampleExternalContract.address);
      expect(externalContractBalance).to.equal(amount);

      // check that the staking contract has 0 balance
      const contractBalance = await ethers.provider.getBalance(stakerContract.address);
      expect(contractBalance).to.equal(0);
    });
  });

• 第一个测试：如果在质押金额没有达到阈值的情况下调用execute()函数，它将撤销交易并返回适当的错误信息。
• 第二个测试：连续两次调用execute()函数，质押已经完成，交易应该被撤销，防止再次调用。
• 第三个测试：在时间到 deadline 之后调用execute()函数。交易应该被撤销，因为只能在时间到 deadline 之前调用execute()函数。
• 最后一个测试：如果所有的要求都满足，那么execute()函数不会回退，并且所有都如预期一样。在函数调用外部合约后，completed变量应该是true，外部合约balance应该等于用户的质押金额，我们的合约余额应该等于0（已经将所有的余额转移到外部合约中）。

如果一切正常，运行yarn test应该会有这样的输出：

完整测试代码

下面我们来看看整个测试代码：

const {ethers} = require('hardhat');
const {use, expect} = require('chai');
const {solidity} = require('ethereum-waffle');

use(solidity);

// Utilities methods
const increaseWorldTimeInSeconds = async (seconds, mine = false) => {
  await ethers.provider.send('evm_increaseTime', [seconds]);
  if (mine) {
    await ethers.provider.send('evm_mine', []);
  }
};

describe('Staker dApp', () => {
  let owner;
  let addr1;
  let addr2;
  let addrs;

  let stakerContract;
  let exampleExternalContract;
  let ExampleExternalContractFactory;

  beforeEach(async () => {
    // Deploy ExampleExternalContract contract
    ExampleExternalContractFactory = await ethers.getContractFactory('ExampleExternalContract');
    exampleExternalContract = await ExampleExternalContractFactory.deploy();

    // Deploy Staker Contract
    const StakerContract = await ethers.getContractFactory('Staker');
    stakerContract = await StakerContract.deploy(exampleExternalContract.address);

    // eslint-disable-next-line no-unused-vars
    [owner, addr1, addr2, ...addrs] = await ethers.getSigners();
  });

  describe('Test contract utils methods', () => {
    it('timeLeft() return 0 after deadline', async () => {
      await increaseWorldTimeInSeconds(180, true);

      const timeLeft = await stakerContract.timeLeft();
      expect(timeLeft).to.equal(0);
    });

    it('timeLeft() return correct timeleft after 10 seconds', async () => {
      const secondElapsed = 10;
      const timeLeftBefore = await stakerContract.timeLeft();
      await increaseWorldTimeInSeconds(secondElapsed, true);

      const timeLeftAfter = await stakerContract.timeLeft();
      expect(timeLeftAfter).to.equal(timeLeftBefore.sub(secondElapsed));
    });
  });

  describe('Test stake() method', () => {
    it('Stake event emitted', async () => {
      const amount = ethers.utils.parseEther('0.5');

      await expect(
        stakerContract.connect(addr1).stake({
          value: amount,
        }),
      )
        .to.emit(stakerContract, 'Stake')
        .withArgs(addr1.address, amount);

      // Check that the contract has the correct amount of ETH we just sent
      const contractBalance = await ethers.provider.getBalance(stakerContract.address);
      expect(contractBalance).to.equal(amount);

      // Check that the contract has stored in our balances state the correct amount
      const addr1Balance = await stakerContract.balances(addr1.address);
      expect(addr1Balance).to.equal(amount);
    });

    it('Stake 0.5 ETH from single user', async () => {
      const amount = ethers.utils.parseEther('0.5');
      const tx = await stakerContract.connect(addr1).stake({
        value: amount,
      });
      await tx.wait();

      // Check that the contract has the correct amount of ETH we just sent
      const contractBalance = await ethers.provider.getBalance(stakerContract.address);
      expect(contractBalance).to.equal(amount);

      // Check that the contract has stored in our balances state the correct amount
      const addr1Balance = await stakerContract.balances(addr1.address);
      expect(addr1Balance).to.equal(amount);
    });

    it('Stake reverted if deadline is reached', async () => {
      // Let deadline be reached
      await increaseWorldTimeInSeconds(180, true);

      const amount = ethers.utils.parseEther('0.5');
      await expect(
        stakerContract.connect(addr1).stake({
          value: amount,
        }),
      ).to.be.revertedWith('Deadline is already reached');
    });

    it('Stake reverted if external contract is completed', async () => {
      const amount = ethers.utils.parseEther('1');
      // Complete the stake process
      const txStake = await await stakerContract.connect(addr1).stake({
        value: amount,
      });
      await txStake.wait();

      // execute it
      const txExecute = await stakerContract.connect(addr1).execute();
      await txExecute.wait();

      await expect(
        stakerContract.connect(addr1).stake({
          value: amount,
        }),
      ).to.be.revertedWith('staking process already completed');
    });
  });

  describe('Test execute() method', () => {
    it('execute reverted because stake amount not reached threshold', async () => {
      await expect(stakerContract.connect(addr1).execute()).to.be.revertedWith('Threshold not reached');
    });

    it('execute reverted because external contract already completed', async () => {
      const amount = ethers.utils.parseEther('1');
      await stakerContract.connect(addr1).stake({
        value: amount,
      });
      await stakerContract.connect(addr1).execute();

      await expect(stakerContract.connect(addr1).execute()).to.be.revertedWith('staking process already completed');
    });

    it('execute reverted because deadline is reached', async () => {
      // reach the deadline
      await increaseWorldTimeInSeconds(180, true);

      await expect(stakerContract.connect(addr1).execute()).to.be.revertedWith('Deadline is already reached');
    });

    it('external contract sucessfully completed', async () => {
      const amount = ethers.utils.parseEther('1');
      await stakerContract.connect(addr1).stake({
        value: amount,
      });
      await stakerContract.connect(addr1).execute();

      // it seems to be a waffle bug see https://github.com/EthWorks/Waffle/issues/469
      // test that our Stake Contract has successfully called the external contract's complete function
      // expect('complete').to.be.calledOnContract(exampleExternalContract);

      // check that the external contract is completed
      const completed = await exampleExternalContract.completed();
      expect(completed).to.equal(true);

      // check that the external contract has the staked amount in it's balance
      const externalContractBalance = await ethers.provider.getBalance(exampleExternalContract.address);
      expect(externalContractBalance).to.equal(amount);

      // check that the staking contract has 0 balance
      const contractBalance = await ethers.provider.getBalance(stakerContract.address);
      expect(contractBalance).to.equal(0);
    });
  });

  describe('Test withdraw() method', () => {
    it('Withdraw reverted if deadline is not reached', async () => {
      await expect(stakerContract.connect(addr1).withdraw(addr1.address)).to.be.revertedWith(
        'Deadline is not reached yet',
      );
    });

    it('Withdraw reverted if external contract is completed', async () => {
      // Complete the stake process
      const txStake = await stakerContract.connect(addr1).stake({
        value: ethers.utils.parseEther('1'),
      });
      await txStake.wait();

      // execute it
      const txExecute = await stakerContract.connect(addr1).execute();
      await txExecute.wait();

      // Let time pass
      await increaseWorldTimeInSeconds(180, true);

      await expect(stakerContract.connect(addr1).withdraw(addr1.address)).to.be.revertedWith(
        'staking process already completed',
      );
    });

    it('Withdraw reverted if address has no balance', async () => {
      // Let time pass
      await increaseWorldTimeInSeconds(180, true);

      await expect(stakerContract.connect(addr1).withdraw(addr1.address)).to.be.revertedWith(
        "You don't have balance to withdraw",
      );
    });

    it('Withdraw success!', async () => {
      // Complete the stake process
      const amount = ethers.utils.parseEther('1');
      const txStake = await stakerContract.connect(addr1).stake({
        value: amount,
      });
      await txStake.wait();

      // Let time pass
      await increaseWorldTimeInSeconds(180, true);

      const txWithdraw = await stakerContract.connect(addr1).withdraw(addr1.address);
      await txWithdraw.wait();

      // Check that the balance of the contract is 0
      const contractBalance = await ethers.provider.getBalance(stakerContract.address);
      expect(contractBalance).to.equal(0);

      // Check that the balance of the user is +1
      await expect(txWithdraw).to.changeEtherBalance(addr1, amount);
    });
  });
});

你是否注意到，测试代码的覆盖率远远大于合约本身？这就是我们想看到的! 测试所有的东西！

本翻译由 CellETF 赞助支持。