erc20.spec.js

let token

const ERC20 = artifacts.require('ERC20')

contract('ERC20', (accounts) => {
  const tokenName = 'My Optimistic Coin'
  const tokenSymbol = 'OPT'
  const tokenDecimals = 1

  beforeEach(async () => {
    token = await ERC20.new(10000, tokenName, tokenDecimals, tokenSymbol, { from: accounts[ 0 ], gasPrice: 0 })
  })

  it('creation: should create an initial balance of 10000 for the creator', async () => {
    const balance = await token.balanceOf.call(accounts[ 0 ], {
      gasPrice: 0
    })
    assert.strictEqual(balance.toNumber(), 10000)
  })

  it('creation: test correct setting of vanity information', async () => {
    const name = await token.name.call()
    assert.strictEqual(name, tokenName)

    const decimals = await token.decimals.call()
    assert.strictEqual(decimals.toNumber(), tokenDecimals)

    const symbol = await token.symbol.call()
    assert.strictEqual(symbol, tokenSymbol)
  })

  it('creation: should succeed in creating over 2^256 - 1 (max) tokens', async () => {
    // 2^256 - 1
    const token2 = await ERC20.new('115792089237316195423570985008687907853269984665640564039457584007913129639935', 'Simon Bucks', 1, 'SBX', { from: accounts[ 0 ], gasPrice: 0 })
    const totalSupply = await token2.totalSupply()
    assert.strictEqual(totalSupply.toString(), '115792089237316195423570985008687907853269984665640564039457584007913129639935')
  })

  // TRANSERS
  // normal transfers without approvals
  it('transfers: ether transfer should be reversed.', async () => {
    const balanceBefore = await token.balanceOf.call(accounts[ 0 ])
    assert.strictEqual(balanceBefore.toNumber(), 10000)

    let threw = false
    try {
      await web3.eth.sendTransaction({ from: accounts[ 0 ], to: token.address, value: web3.utils.toWei('10', 'Ether'), gasPrice: 0 })
    } catch (e) {
      threw = true
    }
    assert.equal(threw, true)

    const balanceAfter = await token.balanceOf.call(accounts[ 0 ])
    assert.strictEqual(balanceAfter.toNumber(), 10000)
  })

  it('transfers: should transfer 10000 to accounts[1] with accounts[0] having 10000', async () => {
    await token.transfer(accounts[ 1 ], 10000, { from: accounts[ 0 ], gasPrice: 0 })
    const balance = await token.balanceOf.call(accounts[ 1 ])
    assert.strictEqual(balance.toNumber(), 10000)
  })

  it('transfers: should fail when trying to transfer 10001 to accounts[1] with accounts[0] having 10000', async () => {
    let threw = false
    try {
      await token.transfer.call(accounts[ 1 ], 10001, { from: accounts[ 0 ], gasPrice: 0 })
    } catch (e) {
      threw = true
    }
    assert.equal(threw, true)
  })

  it('transfers: should handle zero-transfers normally', async () => {
    assert(await token.transfer.call(accounts[ 1 ], 0, { from: accounts[ 0 ], gasPrice: 0 }), 'zero-transfer has failed')
  })

  // NOTE: testing uint256 wrapping is impossible since you can't supply > 2^256 -1
  // todo: transfer max amounts

  // APPROVALS
  it('approvals: msg.sender should approve 100 to accounts[1]', async () => {
    await token.approve(accounts[ 1 ], 100, { from: accounts[ 0 ], gasPrice: 0 })
    const allowance = await token.allowance.call(accounts[ 0 ], accounts[ 1 ])
    assert.strictEqual(allowance.toNumber(), 100)
  })

  // bit overkill. But is for testing a bug
  it('approvals: msg.sender approves accounts[1] of 100 & withdraws 20 once.', async () => {
    const balance0 = await token.balanceOf.call(accounts[ 0 ])
    assert.strictEqual(balance0.toNumber(), 10000)

    await token.approve(accounts[ 1 ], 100, { from: accounts[ 0 ], gasPrice: 0 }) // 100
    const balance2 = await token.balanceOf.call(accounts[ 2 ])
    assert.strictEqual(balance2.toNumber(), 0, 'balance2 not correct')

    await token.transferFrom.call(accounts[ 0 ], accounts[ 2 ], 20, { from: accounts[ 1 ], gasPrice: 0 })
    await token.allowance.call(accounts[ 0 ], accounts[ 1 ])
    await token.transferFrom(accounts[ 0 ], accounts[ 2 ], 20, { from: accounts[ 1 ], gasPrice: 0 }) // -20
    const allowance01 = await token.allowance.call(accounts[ 0 ], accounts[ 1 ])
    assert.strictEqual(allowance01.toNumber(), 80) // =80

    const balance22 = await token.balanceOf.call(accounts[ 2 ])
    assert.strictEqual(balance22.toNumber(), 20)

    const balance02 = await token.balanceOf.call(accounts[ 0 ])
    assert.strictEqual(balance02.toNumber(), 9980)
  })

  // should approve 100 of msg.sender & withdraw 50, twice. (should succeed)
  it('approvals: msg.sender approves accounts[1] of 100 & withdraws 20 twice.', async () => {
    await token.approve(accounts[ 1 ], 100, { from: accounts[ 0 ], gasPrice: 0 })
    const allowance01 = await token.allowance.call(accounts[ 0 ], accounts[ 1 ])
    assert.strictEqual(allowance01.toNumber(), 100)

    await token.transferFrom(accounts[ 0 ], accounts[ 2 ], 20, { from: accounts[ 1 ], gasPrice: 0 })
    const allowance012 = await token.allowance.call(accounts[ 0 ], accounts[ 1 ])
    assert.strictEqual(allowance012.toNumber(), 80)

    const balance2 = await token.balanceOf.call(accounts[ 2 ])
    assert.strictEqual(balance2.toNumber(), 20)

    const balance0 = await token.balanceOf.call(accounts[ 0 ])
    assert.strictEqual(balance0.toNumber(), 9980)

    // FIRST tx done.
    // onto next.
    await token.transferFrom(accounts[ 0 ], accounts[ 2 ], 20, { from: accounts[ 1 ], gasPrice: 0 })
    const allowance013 = await token.allowance.call(accounts[ 0 ], accounts[ 1 ])
    assert.strictEqual(allowance013.toNumber(), 60)

    const balance22 = await token.balanceOf.call(accounts[ 2 ])
    assert.strictEqual(balance22.toNumber(), 40)

    const balance02 = await token.balanceOf.call(accounts[ 0 ])
    assert.strictEqual(balance02.toNumber(), 9960)
  })

  // should approve 100 of msg.sender & withdraw 50 & 60 (should fail).
  it('approvals: msg.sender approves accounts[1] of 100 & withdraws 50 & 60 (2nd tx should fail)', async () => {
    await token.approve(accounts[ 1 ], 100, { from: accounts[ 0 ], gasPrice: 0 })
    const allowance01 = await token.allowance.call(accounts[ 0 ], accounts[ 1 ])
    assert.strictEqual(allowance01.toNumber(), 100)

    await token.transferFrom(accounts[ 0 ], accounts[ 2 ], 50, { from: accounts[ 1 ], gasPrice: 0 })
    const allowance012 = await token.allowance.call(accounts[ 0 ], accounts[ 1 ])
    assert.strictEqual(allowance012.toNumber(), 50)

    const balance2 = await token.balanceOf.call(accounts[ 2 ])
    assert.strictEqual(balance2.toNumber(), 50)

    const balance0 = await token.balanceOf.call(accounts[ 0 ])
    assert.strictEqual(balance0.toNumber(), 9950)

    // FIRST tx done.
    // onto next.
    let threw = false
    try {
      await token.transferFrom.call(accounts[ 0 ], accounts[ 2 ], 60, { from: accounts[ 1 ], gasPrice: 0 })
    } catch (e) {
      threw = true
    }
    assert.equal(threw, true)
  })

  it('approvals: attempt withdrawal from account with no allowance (should fail)', async () => {
    let threw = false
    try {
      await token.transferFrom.call(accounts[ 0 ], accounts[ 2 ], 60, { from: accounts[ 1 ], gasPrice: 0 })
    } catch (e) {
      threw = true
    }
    assert.equal(threw, true)
  })

  it('approvals: allow accounts[1] 100 to withdraw from accounts[0]. Withdraw 60 and then approve 0 & attempt transfer.', async () => {
    await token.approve(accounts[ 1 ], 100, { from: accounts[ 0 ], gasPrice: 0 })
    await token.transferFrom(accounts[ 0 ], accounts[ 2 ], 60, { from: accounts[ 1 ], gasPrice: 0 })
    await token.approve(accounts[ 1 ], 0, { from: accounts[ 0 ], gasPrice: 0 })
    let threw = false
    try {
      await token.transferFrom.call(accounts[ 0 ], accounts[ 2 ], 10, { from: accounts[ 1 ], gasPrice: 0 })
    } catch (e) {
      threw = true
    }
    assert.equal(threw, true)
  })

  it('approvals: approve max (2^256 - 1)', async () => {
    await token.approve(accounts[ 1 ], '115792089237316195423570985008687907853269984665640564039457584007913129639935', { from: accounts[ 0 ], gasPrice: 0 })
    const allowance = await token.allowance(accounts[ 0 ], accounts[ 1 ])
    assert.strictEqual(allowance.toString(), '115792089237316195423570985008687907853269984665640564039457584007913129639935')
  })

  // should approve max of msg.sender & withdraw 20 without changing allowance (should succeed).
  it('approvals: msg.sender approves accounts[1] of max (2^256 - 1) & withdraws 20', async () => {
    const balance0 = await token.balanceOf.call(accounts[ 0 ])
    assert.strictEqual(balance0.toNumber(), 10000)

    const max = '115792089237316195423570985008687907853269984665640564039457584007913129639935'
    await token.approve(accounts[ 1 ], max, { from: accounts[ 0 ], gasPrice: 0 })
    const balance2 = await token.balanceOf.call(accounts[ 2 ])
    assert.strictEqual(balance2.toNumber(), 0, 'balance2 not correct')

    await token.transferFrom(accounts[ 0 ], accounts[ 2 ], 20, { from: accounts[ 1 ], gasPrice: 0 })
    const allowance01 = await token.allowance.call(accounts[ 0 ], accounts[ 1 ])
    assert.strictEqual(allowance01.toString(), max)

    const balance22 = await token.balanceOf.call(accounts[ 2 ])
    assert.strictEqual(balance22.toNumber(), 20)

    const balance02 = await token.balanceOf.call(accounts[ 0 ])
    assert.strictEqual(balance02.toNumber(), 9980)
  })
  
  it('events: should fire Transfer event properly', async () => {
    const res = await token.transfer(accounts[ 1 ], '2666', { from: accounts[ 0 ], gasPrice: 0 })
    const transferLog = res.logs.find(
      element => element.event.match('Transfer') &&
        element.address.match(token.address)
    )
    assert.strictEqual(transferLog.args._from, accounts[ 0 ])
    // L2 ETH transfer also emits a transfer event
    assert.strictEqual(transferLog.args._to, accounts[ 1 ])
    assert.strictEqual(transferLog.args._value.toString(), '2666')
  })

  it('events: should fire Transfer event normally on a zero transfer', async () => {
    const res = await token.transfer(accounts[ 1 ], '0', { from: accounts[ 0 ], gasPrice: 0 })
    const transferLog = res.logs.find(
      element => element.event.match('Transfer') &&
        element.address.match(token.address)
    )
    assert.strictEqual(transferLog.args._from, accounts[ 0 ])
    assert.strictEqual(transferLog.args._to, accounts[ 1 ])
    assert.strictEqual(transferLog.args._value.toString(), '0')
  })

  it('events: should fire Approval event properly', async () => {
    const res = await token.approve(accounts[ 1 ], '2666', { from: accounts[ 0 ], gasPrice: 0 })
    const approvalLog = res.logs.find(element => element.event.match('Approval'))
    assert.strictEqual(approvalLog.args._owner, accounts[ 0 ])
    assert.strictEqual(approvalLog.args._spender, accounts[ 1 ])
    assert.strictEqual(approvalLog.args._value.toString(), '2666')
  })
})