mcmath / chai-iterator Goto Github PK

Hi @mcmath, I just wanted to check as there have been no commits to master since march 2017 and no responce to issues or pull requests that have been around for over a month now.

It would be great to have chai-iterator work with chai@4 so I was wondering if you can find time to fix up and publish a new release to npm. If you are unable to maintain chai-iterator right now I would be very happy to help out in any way I can.

Cheers. 😊

iterable must have an [@@iterator]() method and its return value must be an iterator.
iterator must have an next() method and its return value must be an iteratorResult.
iteratorResult is an object, it must have a boolean done property, and when done property is false, value property must be present.

In other words, if chai really say iterable, it should be possible to get iteratorResult!

It is difficult to obtain iteratorResult on the premise that there are no side effects. (Ex: queue, stack)
However, when calling [@@iterator]() it is very uncommon case that there are side effects other than for debugging purposes.

if (!(value != null && typeof value[Symbol.iterator] === 'function')) {
  return false;
}
const maybeIterator = value[Symbol.iterator]();
if (typeof maybeIterator !== 'object' || typeof maybeIterator.next !== 'function') {
  return false;
}
return true;

Hi,

Thanks for this great package.

I'm trying to use it with TypeScript. Typings are installed and I'm importing it like this:

import * as chaiIterator from 'chai-iterator';

But it gives me the following error:

[ts] Module ''chai-iterator'' resolves to a non-module entity and cannot be imported using this construct.

Any ideas?

I cannot use require syntax.

This code:

import chai = require("chai");
import { expect } from 'chai';
import chaiIterator = require("chai-iterator");

chai.use(chaiIterator);

expect([2, 3, 5]).to.iterate.for.lengthOf(3);

Throws the following error.

AssertionError: expected undefined to be iterable

Here is a repo with reproduction: https://github.com/nunof07/chai-iterator-test

Can't quite figure out is going wrong. _obj is undefined in Assertion.addProperty.

Users should be able to test the length of an iterable, i.e., the number of values it yields before it is done. In particular, the following should be possible:

function* count(max) {
  for (let i = 0; i < max; i++) {
    yield i;
  }
}

count(10).should.iterate.for.lengthOf(10);
count(10).should.iterate.for.length.above(9);
count(10).should.iterate.for.length.below(11);
count(10).should.iterate.for.length.of.at.least(10);
count(10).should.iterate.for.length.of.at.most(10);
count(10).should.iterate.for.length.within(9, 10);

Equivalent assertions should be available using the assert style.

These assertions should be implemented in such a way that the iteration stops as soon as possible, so that even infinite iterators may be tested for length.

Created a class for nodejs, and a vanilla @@iterator implementation according to the reference :

class DStorage {
//...
[Symbol.iterator]() {
  const ctx = this
  return {
    next: () => {
      if (typeof this._current === 'undefined' || typeof this._current.value === 'undefined') return {done: true}
      this._current = this._current.next
      return {value: this._current.value, done: false}
    },
    _current: ctx.root
  }
}

When testing this with chai-iterator the result was:

TypeError: iterable[Symbol.iterator] is not a function

To overcome this issue it turns out that I have to either 1) rewrite the above implementation in a generator form (*[Symbol.iterator]) or 2) I have to add unnecessary extra @@iterator like this:

class DStorage {
//...
[Symbol.iterator]() {
  const ctx = this
  return {
    next: () => {
      if (typeof this._current === 'undefined' || typeof this._current.value === 'undefined') return {done: true}
      this._current = this._current.next
      return {value: this._current.value, done: false}
    },
    _current: ctx.root,
    [Symbol.iterator]() { return this; }
  }
}

The extra [Symbol.iterator] within the iterator is not required or even directly mentioned in the iterable protocol reference.

I'm using chai version 4.1.2. With node version 8.9.1 LTS.

The following program runs just fine:

const chai = require('chai');
chai.assert.isObject({});

but once the chai-iterator library is in use

const chai = require('chai');
const chaiIterator = require('chai-iterator');
chai.use(chaiIterator);
chai.assert.isObject({});

the following error appears:

/Users/mr6502/projects/project/node_modules/chai/lib/chai/assertion.js:141
      throw new AssertionError(msg, {
      ^
AssertionError: expected undefined to be an object
    at Function.assert.isObject (/Users/mr6502/projects/project/node_modules/chai/lib/chai/interface/assert.js:602:58)
    at Object.<anonymous> (/Users/mr6502/projects/project/a.txt:4:13)
    at Module._compile (module.js:635:30)
    at Object.Module._extensions..js (module.js:646:10)
    at Module.load (module.js:554:32)
    at tryModuleLoad (module.js:497:12)
    at Function.Module._load (module.js:489:3)
    at Function.Module.runMain (module.js:676:10)
    at startup (bootstrap_node.js:187:16)
    at bootstrap_node.js:608:3