example.js

var _          = require('lodash')
var mocha      = require('mocha')
var should     = require('should')
var testcheck  = require('testcheck')
var mochaCheck = require('mocha-testcheck').install();
var gen        = testcheck.gen

var DomsStringUtils = {
  truncateBetter: function(input, length) {
    if (length < 0) {
     return ''
    } else if (input.length <= length) {
      return input;
    } else {
      return input.substring(0, length) + '...';
    }
  },

  truncateOrig: function(input, length) {
    if (input.length <= length) {
      return input;
    } else {
      return input.substring(0, length) + '...';
    }
  },

  containsOrig: function(s, substring) {
    return s.indexOf(substring) != -1;
  }
}

describe('DomsStringUtils using "TDD style"', function() {
  
  describe('#truncate', function() {
    it('Should truncate a short string', function(done) {
      DomsStringUtils.truncateOrig('abc', 5).should.eql('abc')
      done()
    })

    it('Should truncate a long string', function(done) {
      DomsStringUtils.truncateOrig('Hello World', 8).should.eql('Hello Wo...')
      done()
    })
  })

  describe('#contains', function() {
    it('Should return true if a string contains another one', function(done) {
      DomsStringUtils.containsOrig('abc', 'bc').should.be.true
      done()
    })

    it('Should return false if a string doesnt contains another one', function(done) {
      DomsStringUtils.containsOrig('abc', '42').should.be.false
      done()
    })
  })
})

describe('DomsStringUtils using "Property based testing style"', function() {

  describe('#truncate', function() {

    check.it('Can handle negative lengths', [gen.alphaNumString, gen.int], function (input, length) {
      var truncated = DomsStringUtils.truncateBetter(input, length);
      if (length < 0) 
        truncated.should.equal('') 
    })

    check.it('Can handle input smaller than lengths', [gen.alphaNumString, gen.int], function (input, length) {
      var truncated = DomsStringUtils.truncateBetter(input, length);
      if (input.length <= length) 
        truncated.should.equal(input) 
    })

    check.it('Can handle input greater than lengths', [gen.alphaNumString, gen.int], function (input, length) {
      var truncated = DomsStringUtils.truncateBetter(input, length);
      if (input.length > length && length > 0) 
        truncated.should.equal(input.substring(0, length) + '...')
    })
  })

  describe('#contains', function() {

    check.it('Testing if a string comprising 3 strings, contains each of those individually.', [gen.alphaNumString, gen.alphaNumString, gen.alphaNumString], function (s1, s2, s3) {
      var inputStr = s1 + s2 + s3
      DomsStringUtils.containsOrig(inputStr, s1)
      DomsStringUtils.containsOrig(inputStr, s2)
      DomsStringUtils.containsOrig(inputStr, s3)
    })
  })

})