Add `closeEnough` assertion to chai. See https://github.com/chaijs/chai/issues/89

assert-close-enough.js

// DO NOT USE!

// This was a quick-and-dirty attempt to handle the problem.

// Use this package, instead: https://www.npmjs.com/package/nearlyequal



/*
const assert = require('chai').assert;

assert.closeEnough = function(actual, expected, message) {
  const scale = Math.abs(actual)/2 + Math.abs(expected)/2;
  if (scale === 0) return true;  // guard against dividing by zero
  const epsilon =  Math.abs(actual - expected) / scale;
  if (epsilon < 1E-13) return true;
  assert.fail(actual, expected, message, 'closeEnough');
};

// To test: `node assert-close-enough.js --test`
if (typeof process === 'object' && process && 'argv' in process) {
  const argv = process.argv;
  if (argv.pop() === '--test') {
    console.log('Testing ...');
    const cases = [2.3453434E23, 2.3453434E-23, 0.5];
    cases.forEach(function(expected) {
      actual = Math.exp(Math.log(expected));
      assert.closeEnough(expected, actual,
        'not closeEnough; expected: ' + expected + ', actual: ' + actual);
    });
    console.log('all good');
  }
}
*/