Cannot create a Big Number

[aress31]

I am trying to create a BN object from the value 10**32, see the following test:

  it("has a quadrilllion (10^15) initial total supply", async () => {
    const decimals = await this.token.decimals();
    const totalSupply = await this.token.totalSupply();
    // console.log(totalSupply);
    console.log(new BN(10 ** 32));
    // console.log((10 ** 15 * 10 ** decimals.toNumber()).toString());
    // console.log(totalSupply, expected);
    // expect(await this.token.totalSupply()).to.be.bignumber.equal(
    //   (10 ** 15 * 10 ** decimals.toNumber()).toString()
    // );
  });

But it seems that the library cannot handle this Big Number, see the following stack trace:

  1) Contract: Initial State
       has a quadrilllion (10^15) initial total supply:
     Error: Assertion failed
      at assert (node_modules\bn.js\lib\bn.js:6:21)
      at BN._initNumber (node_modules\bn.js\lib\bn.js:128:7)
      at BN.init [as _init] (node_modules\bn.js\lib\bn.js:82:19)
      at new BN (node_modules\bn.js\lib\bn.js:39:12)
      at Context.<anonymous> (test\ERC20Deflationary.test.js:35:17)
      at processTicksAndRejections (internal/process/task_queues.js:93:5)

I also tried to initialise the Big Number with a string instead but the value is totally off, see:

  it("has a quadrilllion (10^15) initial total supply", async () => {
    const decimals = await this.token.decimals();
    const totalSupply = await this.token.totalSupply();
    // console.log(totalSupply);
    console.log(new BN((10 ** 32).toString()));
    // console.log((10 ** 15 * 10 ** decimals.toNumber()).toString());
    // console.log(totalSupply, expected);
    // expect(await this.token.totalSupply()).to.be.bignumber.equal(
    //   (10 ** 15 * 10 ** decimals.toNumber()).toString()
    // );
  });

  Contract: Initial State
    √ the deployer is the owner (104ms)
    √ has a name (124ms)
    √ has a symbol (124ms)
    √ has 18 decimals (87ms)
BN { negative: 0, words: [ 23532 ], length: 1, red: null }
    √ has a quadrilllion (10^15) initial total supply (173ms)
    1) assigns the initial total supply to the owner
    > No events were emitted

Could anyone please help?

[shuckster]

console.log('1', 10 ** 32)
console.log('2', new BigNumber(10 ** 32).toString())
console.log('3', new BigNumber(10).exponentiatedBy(32).toString())
// 1 1e+32
// 2 1e+32
// 3 1e+32

Seems fine.

Are you sure you're interpreting your test correctly?

  Contract: Initial State
   (...cut...)
    √ has a quadrilllion (10^15) initial total supply (173ms) <-- PASS
    1) assigns the initial total supply to the owner <-- FAIL
    > No events were emitted

The it you posted does not have the description "assigns the initial total supply to the owner"?

[aress31]

@shuckster thanks for trying to help, maybe this output will be more ufsefull:

  it("has a quadrilllion (10^15) initial total supply", async () => {
    const decimals = await this.token.decimals();
    const totalSupply = await this.token.totalSupply();
    console.log(totalSupply.toString());
    console.log("1", 10 ** 32);
    console.log("2", BN(10 ** 32).toString());
    console.log("3", BN(10).exponentiatedBy(32).toString());
    // console.log(new BN(expected));
    // console.log((10 ** 15 * 10 ** decimals.toNumber()).toString());
    // console.log(totalSupply, expected);
    // expect(await this.token.totalSupply()).to.be.bignumber.equal(
    //   (10 ** 15 * 10 ** decimals.toNumber()).toString()
    // );
  });

  Contract: Initial State
    √ the deployer is the owner (76ms)
    √ has a name (110ms)
    √ has a symbol (108ms)
    √ has 18 decimals (98ms)
1000000000000000000000000000000000
1 1e+32
    1) has a quadrilllion (10^15) initial total supply
    > No events were emitted

  4 passing (1s)
  1 failing

  1) Contract: Initial State
       has a quadrilllion (10^15) initial total supply:
     TypeError: Cannot set property 'negative' of undefined
      at BN (node_modules\bn.js\lib\bn.js:26:19)
      at Context.<anonymous> (test\ERC20Deflationary.test.js:36:22)
      at processTicksAndRejections (internal/process/task_queues.js:93:5)

Btw I am using BN from @openzeppelin/test-helpers not sure if it is based on this lib.

EDIT: Alright it is based on:

require('../configure')();

const web3 = require('./config/web3').getWeb3();

const BN = web3.utils.BN;
const chaiBN = require('chai-bn')(BN);

require('chai').use(chaiBN);

// Installing chai-bn for the user is part of the offering.
//
// The chai module used internally by us may not be the same one that the user
// has in their own tests. This can happen if the version ranges required don't
// intersect, or if the package manager doesn't dedupe the modules for any
// other reason. We do our best to install chai-bn for the user.
for (const mod of [require.main, module.parent]) {
  try {
    mod.require('chai').use(chaiBN);
  } catch (e) {
    // Ignore errors
  }
}

module.exports = {
  web3,
  BN,
};

EDIT 1: I switched to this library instead and it handles exponential 32 fine, however , the default BN format returned by web3 (see totalSupply) apperars to be different from the one used in this lib, therefore, I am not sure if my expect see this output:

  it("has a quadrilllion (10^15) initial total supply", async () => {
    const decimals = await this.token.decimals();
    const totalSupply = await this.token.totalSupply();
    console.log("totalSupply", totalSupply);
    console.log("1", 10 ** 32);
    console.log("2",  new BigNumber(10 ** 32));
    console.log("3",  new BigNumber(10).exponentiatedBy(32));
    console.log("4",  new BigNumber(10).exponentiatedBy(15 + decimals));
    // console.log(new BN(expected));
    // console.log((10 ** 15 * 10 ** decimals.toNumber()).toString());
    // console.log(totalSupply, expected);
    // expect(await this.token.totalSupply()).to.be.bignumber.equal(
    //   (10 ** 15 * 10 ** decimals.toNumber()).toString()
    // );
  });

  Contract: Initial State
    √ the deployer is the owner (125ms)
    √ has a name (89ms)
    √ has a symbol (140ms)
    √ has 18 decimals (73ms)
totalSupply BN {
  negative: 0,
  words: [ 0, 5685888, 14234508, 20388114, 49, <1 empty item> ],
  length: 5,
  red: null
}
1 1e+32
2 BigNumber { s: 1, e: 32, c: [ 10000 ] }
3 BigNumber { s: 1, e: 32, c: [ 10000 ] }
4 BigNumber { s: 1, e: 1518, c: [ 1000000 ] }
    √ has a quadrilllion (10^15) initial total supply (258ms)

Does anyone know what I should do?

[shuckster]

I think you're asking for help in the wrong place.

Despite being based on bignumber.js, the error you're getting seems more to do with the fork.

Maybe ask bn.js for help?

[aress31]

I managed to get it work this way:

    expect(await this.token.totalSupply()).to.be.bignumber.equal(
      new BigNumber(10).exponentiatedBy(33).toFixed()
    );

Just wondering how I could do something like that:

const decimals = await this.token.decimals();
console.log(new BigNumber(10).exponentiatedBy(15 + decimals));

[shuckster]

Is this what you're looking for?

new BigNumber(10).exponentiatedBy(15).toFormat(2)

[aress31]

No decimals is 15 basically I want to sum 15 + 18 since decimals is variable and my test depends on this value.

[shuckster]

If you want the whole expression to be BigNumber you could do this:

BigNumber(10).exponentiatedBy(BigNumber.sum(15, decimals))

But I don't think it's necessary?

Calculating the size of the exponent only needs integer arithmetic like you already showed:

BigNumber(10).exponentiatedBy(15 + decimals)

That should give the same answer as the first one, right?

[aress31]

Thanks for the help @shuckster but the way I did it (15 + decimals) actually output 1518 instead of 33.

Therefore, I think that the BigNumber alternative is the way to go.

[shuckster]

I just had a closer look at your error logs.

I think the problem is this.token.decimals(); produces a string:

const decimals = await this.token.decimals();

15 + 18
// 33

15 + "18"
// "1518"

15 + decimals
// "1518", right?

So you could fix it like this:

15 + parseInt(decimals, 10)

Or just make sure this.token.decimals(); returns a number?

[aress31]

It returns a BigNumber not a string but maybe the + sign somehow force a toString() conversion, will try your version and let you know how it works. Will also try to call toNumber().

[shuckster]

Ah, if decimals is already a BigNumber then you should be able to do:

decimals.plus(15)

[aress31]

Thanks a lot @shuckster, you helped me solved my issue. Although, I have to juggle between BN and BigNumber library which is less than optimal but BN does not seem to handle the very large numbers I am processing.

This is my solution:

  it("has a quadrilllion (10^15) initial total supply", async () => {
    const decimals = await this.token.decimals();
    const totalSupply = await this.token.totalSupply();

    expect(await this.token.totalSupply()).to.be.bignumber.equal(
      new BigNumber(10).exponentiatedBy(decimals.add(new BN(15))).toFixed()
    );
  });

[shuckster]

Glad you hear you fixed it!