Sentence reverse - mocking experience

sentenceReverse_mockingPractice.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ReverseSentence
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(reverseWords("perfect makes practice".ToCharArray()));
        }

        static char[] reverseWords(char[] arr)
        {
            // your code goes here
            if (arr == null || arr.Length == 0)
            {
                return new char[0];
            }

            reverseString(arr, 0, arr.Length - 1); // 

            // reverse each word 
            reverseEachWord(arr);
            return arr;
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="arr"></param>
        private static void reverseEachWord(char[] arr)
        {
            int length = arr.Length;

            int start = 0;  // "a ", "ab b " 
            for (int i = 0; i < length; i++)
            {
                var visit = arr[i];
                bool visitIsSpace = visit == ' ';

                var startChar = arr[start];
                bool startIsSpace = startChar == ' ';
                if (startIsSpace)
                {
                    start = i; // mark the word start 
                }

                bool isLastChar = i == (length - 1); 
                bool foundWord = !startIsSpace && visitIsSpace; // "ab ", "ab cd"  " practice"
                bool foundWordCase1 = (foundWord && (i - 1 - start) >= 0);
                bool foundWordCase2 = !startIsSpace && !visitIsSpace && isLastChar;

                if (foundWordCase1 || foundWordCase2)
                {
                    var end = isLastChar ? i : (i - 1); // bug in mocking experience, missing isLastChar end = i instead of i - 1. 
                    reverseString(arr, start, end);
                    start = i + 1;   // start new word 
                }
            }
        }

        private static void reverseString(char[] arr, int start, int end)
        {
            if (start >= end)
            {
                return;
            }

            while (start < end)
            {
                var tmp = arr[start];
                arr[start] = arr[end];
                arr[end] = tmp;

                start++;
                end--; 
            }
        }        
    }
}