Audit Kata

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Kata Description

The problem that this code is designed to solve is explained here: Audit.

The code is available in the Audit folder.

The System

AuditManager is the main class in the application. Its constructor accepts the maximum number of entries per file and the working directory as configuration parameters.

namespace Audit
{
    public class AuditManager
    {
        private readonly int _maxEntriesPerFile;
        private readonly string _directoryName;
        private readonly IFileSystem _fileSystem;

        public AuditManager(
            int maxEntriesPerFile, 
            string directoryName,
            IFileSystem fileSystem)
        {
            _maxEntriesPerFile = maxEntriesPerFile;
            _directoryName = directoryName;
            _fileSystem = fileSystem;
        }
    
        public void AddRecord(string visitorName, DateTime timeOfVisit)
        {
            string[] filePaths = _fileSystem.GetFiles(_directoryName);
            (int index, string path)[] sorted = SortByIndex(filePaths);
            var newRecord = visitorName + ';' + timeOfVisit.ToString("yyyy-MM-dd HH:mm:ss");
        
            if (sorted.Length == 0)
            {
                string newFile = Path.Combine(_directoryName, "audit_1.txt");
                _fileSystem.WriteAllText(newFile, newRecord);
            
                return;
            }
        
            (int currentFileIndex, string currentFilePath) = sorted.Last();
            List<string> lines = _fileSystem.ReadAllLines(currentFilePath).ToList();
        
            if (lines.Count < _maxEntriesPerFile)
            {
                lines.Add(newRecord);
                string newContent = string.Join(Environment.NewLine, lines);
                _fileSystem.WriteAllText(currentFilePath, newContent);
            }
            else
            {
                int newIndex = currentFileIndex + 1;
                string newName = $"audit_{newIndex}.txt";
                string newFile = Path.Combine(_directoryName, newName);
                _fileSystem.WriteAllText(newFile, newRecord);
            }
        }

        private static (int index, string path)[] SortByIndex(string[] filePaths)
            => filePaths
                .AsEnumerable()
                .Select((path, index) => (index + 1, path))
                .ToArray();
    }
}

The only public method in the class is AddRecord, which does all the work of the audit system:

• Retrieves a full list of files from the working directory
• Sorts them by index (all filenames follow the same pattern: audit_{index}.txt [for example, audit_1.txt])
• If there are no audit files yet, creates a first one with a single record
• If there are audit files, gets the most recent one and either appends the new record to it or creates a new file, depending on whether the number of entries in that file has reached the limit

Learning hour

You can use this code to prepare / practice this learning hour: Styles of Unit Tests.