mockString function

String mockString([ int lengthOfMockedString = 16, String include = '!' ])

Generate random string.

lengthOfMockedString defines string length. Throws ArgumentError if length is less than or equal to 0. Default value is 16.

include defines set of characters that are generated for string. It can be any combination of 'a', 'A' or '#'.

• 'a' represents lowercase characters.
• 'A' represents uppercase characters.
• '#' represents digits, 0 to 9.

Default value of include is '!' which is equal to combination of 'aA#'.

Throws ArgumentError if it contains any letter other than 'a', 'A', '#' or '!'.

Example usage:

  mockString(4)       // returns string of length 4 which is
                      // consisted of any combination of
                      // lowercase letters, uppercase letters
                      // and digits.
                      // Example: Dg3C, H77a, B1LK etc.
  mockString(7, 'a#') // returns string of length 7 which is
                      // consisted of any combination of
                      // lowercase letters and digits.
                      // Example: g5a6hjc, 4hn9m3e, 6dei5e2 etc.
  mockString(5, '#')  // returns string of length 5 which is
                      // consisted of digits.
                      // Example: 51321, 74214, 06910 etc.

Implementation

String mockString([int lengthOfMockedString = 16, String include = '!']) {
  // Check for validity of parameters.

  lengthOfMockedString <= 0
      ? throw ArgumentError('Length must be integer '
          'higher than 0')
      : null;

  include.isEmpty ? throw ArgumentError('Empty include parameter') : null;

  include.split('').forEach((s) {
    if (!('aA#!'.contains(s))) throw ArgumentError('Invalid include parameter');
  });

  // Representation of all characters that will be generated
  // based on [include] parameter.
  var allChars = StringBuffer();

  for (var c in include.split('')) {
    if (c.contains('!')) {
      allChars.writeAll(
          ['abcdefghijklmnopqrstuvwxyz', 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'],
          '0123456789');
      break;
    }
    switch (c) {
      case 'a':
        allChars.write('abcdefghijklmnopqrstuvwxyz');
        break;
      case 'A':
        allChars.write('ABCDEFGHIJKLMNOPQRSTUVWXYZ');
        break;
      case '#':
        allChars.write('0123456789');
        break;
      default:
        break;
    }
  }

  // Generate sequence of chars with length == [lengthOfMockedString]
  return List<String>.generate(lengthOfMockedString,
      (_) => allChars.toString()[random.nextInt(allChars.length)]).join();
}