text: // test sign
  const assert = require('assert')
  const approx = require('../../../tools/approx')
  const math = require('../../../src/main')
  const bignumber = math.bignumber
  const fraction = math.fraction
  const complex = math.complex
  
  describe('sign', function () {
    it('should calculate the sign of a boolean', function () {
      assert.equal(math.sign(true), 1)
      assert.equal(math.sign(false), 0)
    })
  
    it('should calculate the sign of a number', function () {
      assert.equal(math.sign(3), 1)
      assert.equal(math.sign(-3), -1)
      assert.equal(math.sign(0), 0)
    })
  
    it('should calculate the sign of a big number', function () {
      assert.deepEqual(math.sign(bignumber(3)), bignumber(1))
      assert.deepEqual(math.sign(bignumber(-3)), bignumber(-1))
      assert.deepEqual(math.sign(bignumber(0)), bignumber(0))
    })
  
    it('should calculate the sign of a fraction', function () {
      const a = fraction(0.5)
      assert(math.sign(a) instanceof math.type.Fraction)
      assert.equal(math.sign(a).toString(), '1')
      assert.equal(math.sign(fraction(-0.5)).toString(), '-1')
      assert.equal(a.toString(), '0.5')
    })
  
    it('should calculate the sign of a complex value', function () {
      approx.deepEqual(math.sign(math.complex(2, -3)), math.complex(0.554700196225229, -0.832050294337844))
    })
  
    it('should calculate the sign of a unit', function () {
      assert.equal(math.sign(math.unit('5 cm')), 1)
      assert.equal(math.sign(math.unit('-5 kg')), -1)
      assert.equal(math.sign(math.unit('0 mol/s')), 0)
      assert.equal(math.sign(math.unit('-283.15 degC')), -1)
      assert.equal(math.sign(math.unit('-273.15 degC')), 0)
      assert.equal(math.sign(math.unit('-263.15 degC')), 1)
  
      assert.deepEqual(math.sign(math.unit(bignumber(5), 'cm')), bignumber(1))
      assert.deepEqual(math.sign(math.unit(bignumber(-5), 'cm')), bignumber(-1))
      assert.deepEqual(math.sign(math.unit(fraction(5), 'cm')), fraction(1))
      assert.deepEqual(math.sign(math.unit(fraction(-5), 'cm')), fraction(-1))
  
      assert.deepEqual(math.sign(math.unit(complex(3, 4), 'mi')), complex(0.6, 0.8))
    })
  
    it('should throw an error when used with a string', function () {
      assert.throws(function () { math.sign('hello world') })
    })
  
    it('should return a matrix of the signs of each elements in the given array', function () {
      assert.deepEqual(math.sign([-2, -1, 0, 1, 2]), [-1, -1, 0, 1, 1])
    })
  
    it('should return a matrix of the signs of each elements in the given matrix', function () {
      assert.deepEqual(math.sign(math.matrix([-2, -1, 0, 1, 2])), math.matrix([-1, -1, 0, 1, 1]))
    })
  
    it('should throw an error in case of invalid number of arguments', function () {
      assert.throws(function () { math.sign() }, /TypeError: Too few arguments/)
      assert.throws(function () { math.sign(1, 2) }, /TypeError: Too many arguments/)
    })
  
    it('should throw an in case of wrong type of arguments', function () {
      assert.throws(function () { math.sign(null) }, /TypeError: Unexpected type of argument/)
    })
  
    it('should LaTeX sign', function () {
      const expression = math.parse('sign(-4)')
      assert.equal(expression.toTex(), '\\mathrm{sign}\\left(-4\\right)')
    })
  })
  