ActiveDirectoryService-GetUserByUserName

ActiveDirectoryService.cs

public class ActiveDirectoryService
{
    private readonly NetworkCredential credentials;

    public ActiveDirectoryService(NetworkCredential credentials)
    {
       this.credentials = credentials;
    }

    public GetUserByResponse GetUserBy(string username)
    {
       const string domain = "LDAP://TODO";

       using (var directoryEntry = new DirectoryEntry(domain, credentials.UserName, credentials.Password))
       using (var directorySearcher = new DirectorySearcher(
          searchRoot: directoryEntry, 
          filter: "OU=Users" /* Improve filter if possible */
          ) 
       {
          Filter = $"sAMAccountName={username}",
          PageSize = 1,
       })
       {
          var result = directorySearcher.FindOne();
          return new GetUserByResponse(result);
       }
    }

    public class GetUserByResponse
    {
       private readonly SearchResult result;

       public GetUserByResponse(SearchResult result)
       {
          this.result = result;
       }

       public bool Found => result != null;
       public bool NotFound => !Found;

       public string Username => GetSingle("sAMAccountName", result);
       public string Company => GetSingle("company", result);
       public string Department => GetSingle("department", result);
       public string Title => GetSingle("title", result);
       public ICollection<string> MemberOf => GetAll("memberOf", result);

       public override string ToString()
       {
          if (result == null)
             return string.Empty;

          var sb = new StringBuilder();

          foreach (string name in result.Properties.PropertyNames)
          {
             for (var index = 0; index < result.Properties[name].Count; index++)
                sb.AppendLine($"{name}-{index}: {result.Properties[name][index].ToString()}");
          }

          return sb.ToString();
       }

       #region Helpers

       private static string GetSingle(string key, SearchResult result)
       {
          return result?.Properties[key]?[0]?.ToString();
       }

       private static ICollection<string> GetAll(string key, SearchResult result)
       {
          var items = new List<string>();

          if (result == null)
             return items;

          var collection = result.Properties[key];

          foreach (var item in collection)
          {
             items.Add(item.ToString());
          }

          return items;
       }

       #endregion
    }
 }

ActiveDirectoryServiceTests.cs

public class ActiveDirectoryServiceTests
{
    private readonly NetworkCredential credentials = new NetworkCredential("<Username>", "<Password>");

    [Explicit]
    [TestCase("ok1")] // OSLO
    [TestCase("ok2")] // OSLO
    public void GetUserBy_ShouldSucceed(string username)
    {
       var service = new ActiveDirectoryService(credentials);

       var result = service.GetUserBy(username);

       Trace.WriteLine(result);

       result.Found.Should().BeTrue();
       result.Username.Should().Be(username);
       result.MemberOf.Should().NotBeEmpty();
    }

    [Explicit]
    [TestCase("shouldnotpass")] 
    public void GetUserBy_ShouldFail(string username)
    {
       var service = new ActiveDirectoryService(credentials);

       var result = service.GetUserBy(username);

       result.NotFound.Should().BeTrue();
       result.Username.Should().Be(null);
       result.MemberOf.Should().BeEmpty();
    }
 }