C# UnitTest Helpers

RandData.cs

namespace UnitTestHelpers
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;

    /// <summary>
    /// Provides random test data
    /// </summary>
    public static class RandData
    {
        private static readonly Random Rand = new Random();
        private static readonly char[] AlphaNumericCharacters = @"0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ".ToCharArray();
        private static readonly char[] PunctuationCharacters = @" .,\/;:-".ToCharArray();

        /// <summary>
        /// Builds random part numbers in the form of xxx-xxxx-xxx. The last section may have up to 5 numbers and letters. (ie. 001AA)
        /// </summary>
        /// <returns><see cref="String"/> of a generated part number.</returns>
        public static string RandomPartNumber()
        {
            var sb = new StringBuilder();

            // generate the digits
            var digits = new int[10];

            for (int i = 0; i < digits.Length; i++)
            {
                digits[i] = Rand.Next(0, 9);
            }

            foreach (var digit in digits)
            {
                sb.Append((char)('0' + digit));
            }

            // is it a snapshot? (25% odds)
            if (Rand.NextDouble() < 0.25)
            {
                // generate a snapshot value
                int snapshotNum = 1;

                // the odds of a successive snapshot is increasingly rare (75% of the time)
                while (Rand.NextDouble() < 0.75)
                {
                    snapshotNum++;
                }

                if (snapshotNum > ('Z' - 'A'))
                {
                    sb.Append((char)('A' + snapshotNum - ('Z' - 'A')));
                    snapshotNum = snapshotNum - ('Z' - 'A');
                }

                sb.Append((char)('A' + snapshotNum));
            }

            // add the dashes
            sb.Insert(3, '-');
            sb.Insert(8, '-');

            return sb.ToString();
        }

        /// <summary>
        /// Builds random text of the specified length.
        /// </summary>
        /// <param name="minLength">Length of the min.</param>
        /// <param name="maxLength">Length of the max.</param>
        /// <returns><see cref="String"/> of a generated phrase</returns>
        public static string Text(int minLength, int maxLength)
        {
            var sb = new StringBuilder();

            var stringLength = Rand.Next(minLength, maxLength);

            for (int i = 0; i < stringLength; i++)
            {
                if (Rand.NextDouble() < 0.10)
                {
                    // add punctuation
                    sb.Append(PunctuationCharacters[Rand.Next(0, PunctuationCharacters.Length - 1)]);
                }
                else
                {
                    // add characters
                    sb.Append(AlphaNumericCharacters[Rand.Next(0, AlphaNumericCharacters.Length - 1)]);
                }
            }

            return sb.ToString();
        }

        /// <summary>
        /// Builds random alpha numeric text of the specified length.
        /// </summary>
        /// <param name="minLength">Length of the min.</param>
        /// <param name="maxLength">Length of the max.</param>
        /// <returns><see cref="String"/> of a generated phrase</returns>
        public static string Alphanumeric(int minLength, int maxLength)
        {
            var sb = new StringBuilder();

            var stringLength = Rand.Next(minLength, maxLength);

            for (int i = 0; i < stringLength; i++)
            {
                // add characters
                sb.Append(AlphaNumericCharacters[Rand.Next(0, AlphaNumericCharacters.Length - 1)]);
            }

            return sb.ToString();
        }

        /// <summary>
        /// Returns a random number between the min and max value.
        /// </summary>
        /// <param name="minValue">The min value.</param>
        /// <param name="maxValue">The max value.</param>
        /// <returns>A double-precision floating point number greater than or equal to minValue, and less than maxValue.</returns>
        public static double Double(double minValue, double maxValue)
        {
            return (Rand.NextDouble() * (maxValue - minValue)) + minValue;
        }

        /// <summary>
        /// Returns a random number between 0.0 and 1.0. 
        /// </summary>
        /// <returns>A double-precision floating point number greater than or equal to 0.0, and less than 1.0.</returns>
        public static double Double()
        {
            return Rand.NextDouble();
        }
    }
}