Tests

const mocha = require('mocha')
const sinon = require('sinon')
const chai = require('chai')

const PRECISION_DIGITS = 14
let floatEqualityComparer = (a, b) => {
  let diff = Math.abs(a - b)
  let c = Math.log10(Math.abs(Math.max(a, b)) || 1)
  let epsilon = Math.pow(10, c - PRECISION_DIGITS)
  return diff < epsilon
}

let expect = chai.expect
describe('Tests', function () {
  it('Test 1', function () {
    let equal = floatEqualityComparer(0, 0)
    expect(equal).to.be.true
  })
  it('Test 2', function () {
    let equal = floatEqualityComparer(0.1 + 0.2, 0.15 + 0.15)
    expect(equal).to.be.true
  })
  it('Test 3', function () {
    let equal = floatEqualityComparer((1 / 3) * 3, 1)
    expect(equal).to.be.true
  })
  it('Test 4', function () {
    let equal = floatEqualityComparer(0, 1 - 1)
    expect(equal).to.be.true
  })
  it('Test 5', function () {
    let equal = floatEqualityComparer(1E10, Math.pow(10, 10))
    expect(equal).to.be.true
  })
  it('Test 6', function () {
    let equal = floatEqualityComparer(1E11, 1.1E11)
    expect(equal).to.be.false
  })
  it('Test 7', function () {
    let equal = floatEqualityComparer(0, 0.1)
    expect(equal).to.be.false
  })
  it('Test 8', function () {
    let equal = floatEqualityComparer(-0.1, 0.1)
    expect(equal).to.be.false
  })
  it('Test 9', function () {
    let equal = floatEqualityComparer(Number.MAX_VALUE, Number.POSITIVE_INFINITY)
    expect(equal).to.be.false
  })
  it('Test 10', function () {
    let equal = floatEqualityComparer(0.9, 1)
    expect(equal).to.be.false
  })
  it('Test 11', function () {
    let equal = floatEqualityComparer(1.999999, 2)
    expect(equal).to.be.false
  })
  it('Test 12', function () {
    let equal = floatEqualityComparer(1E20, 1E21)
    expect(equal).to.be.false
  })
  it('Test 13', function () {
    let equal = floatEqualityComparer(1E200, 1E201)
    expect(equal).to.be.false
  })
  it('Should be equal if difference is too small', function () {
    let equal = floatEqualityComparer(1, 1.0000000000000001)
    expect(equal).to.be.true
  })
  it('Should be equal if difference is too small', function () {
    let equal = floatEqualityComparer(1E200, 1.000000000000001E200)
    expect(equal).to.be.true
  })
})