openzeppelin-contracts/test/token/ERC20/TokenVesting.test.js

const { expectThrow } = require('../../helpers/expectThrow');
const { EVMRevert } = require('../../helpers/EVMRevert');
const { latestTime } = require('../../helpers/latestTime');
const { increaseTimeTo, duration } = require('../../helpers/increaseTime');
const { ethGetBlock } = require('../../helpers/web3');

const BigNumber = web3.BigNumber;

require('chai')
  .use(require('chai-bignumber')(BigNumber))
  .should();

const ERC20Mintable = artifacts.require('ERC20Mintable');
const TokenVesting = artifacts.require('TokenVesting');

contract('TokenVesting', function ([_, owner, beneficiary]) {
  const amount = new BigNumber(1000);
  const ZERO_ADDRESS = '0x0000000000000000000000000000000000000000';

  beforeEach(async function () {
    this.start = (await latestTime()) + duration.minutes(1); // +1 minute so it starts after contract instantiation
    this.cliff = duration.years(1);
    this.duration = duration.years(2);
  });

  it('rejects a duration shorter than the cliff', async function () {
    const cliff = this.duration;
    const duration = this.cliff;

    cliff.should.be.gt(duration);

    await expectThrow(
      TokenVesting.new(beneficiary, this.start, cliff, duration, true, { from: owner })
    );
  });

  it('requires a valid beneficiary', async function () {
    await expectThrow(
      TokenVesting.new(ZERO_ADDRESS, this.start, this.cliff, this.duration, true, { from: owner })
    );
  });

  context('once deployed', function () {
    beforeEach(async function () {
      this.vesting = await TokenVesting.new(beneficiary, this.start, this.cliff, this.duration, true, { from: owner });

      this.token = await ERC20Mintable.new({ from: owner });
      await this.token.mint(this.vesting.address, amount, { from: owner });
    });

    it('cannot be released before cliff', async function () {
      await expectThrow(
        this.vesting.release(this.token.address),
        EVMRevert,
      );
    });

    it('can be released after cliff', async function () {
      await increaseTimeTo(this.start + this.cliff + duration.weeks(1));
      await this.vesting.release(this.token.address);
    });

    it('should release proper amount after cliff', async function () {
      await increaseTimeTo(this.start + this.cliff);

      const { receipt } = await this.vesting.release(this.token.address);
      const block = await ethGetBlock(receipt.blockNumber);
      const releaseTime = block.timestamp;

      (await this.token.balanceOf(beneficiary)).should.bignumber.equal(
        amount.mul(releaseTime - this.start).div(this.duration).floor()
      );
    });

    it('should linearly release tokens during vesting period', async function () {
      const vestingPeriod = this.duration - this.cliff;
      const checkpoints = 4;

      for (let i = 1; i <= checkpoints; i++) {
        const now = this.start + this.cliff + i * (vestingPeriod / checkpoints);
        await increaseTimeTo(now);

        await this.vesting.release(this.token.address);
        const expectedVesting = amount.mul(now - this.start).div(this.duration).floor();
        (await this.token.balanceOf(beneficiary)).should.bignumber.equal(expectedVesting);
      }
    });

    it('should have released all after end', async function () {
      await increaseTimeTo(this.start + this.duration);
      await this.vesting.release(this.token.address);
      (await this.token.balanceOf(beneficiary)).should.bignumber.equal(amount);
    });

    it('should be revoked by owner if revocable is set', async function () {
      await this.vesting.revoke(this.token.address, { from: owner });
    });

    it('should fail to be revoked by owner if revocable not set', async function () {
      const vesting = await TokenVesting.new(
        beneficiary, this.start, this.cliff, this.duration, false, { from: owner }
      );

      await expectThrow(
        vesting.revoke(this.token.address, { from: owner }),
        EVMRevert,
      );
    });

    it('should return the non-vested tokens when revoked by owner', async function () {
      await increaseTimeTo(this.start + this.cliff + duration.weeks(12));

      const vested = await this.vesting.vestedAmount(this.token.address);

      await this.vesting.revoke(this.token.address, { from: owner });

      (await this.token.balanceOf(owner)).should.bignumber.equal(amount.sub(vested));
    });

    it('should keep the vested tokens when revoked by owner', async function () {
      await increaseTimeTo(this.start + this.cliff + duration.weeks(12));

      const vestedPre = await this.vesting.vestedAmount(this.token.address);

      await this.vesting.revoke(this.token.address, { from: owner });

      const vestedPost = await this.vesting.vestedAmount(this.token.address);

      vestedPre.should.bignumber.equal(vestedPost);
    });

    it('should fail to be revoked a second time', async function () {
      await increaseTimeTo(this.start + this.cliff + duration.weeks(12));

      await this.vesting.vestedAmount(this.token.address);

      await this.vesting.revoke(this.token.address, { from: owner });

      await expectThrow(
        this.vesting.revoke(this.token.address, { from: owner }),
        EVMRevert,
      );
    });
  });
});