This Gist demonstrates how to use NUnits Action Attributes in order to create and delete a temporary directory on test case level.

ActionAttributeDemoTest.cs

[TestFixture]
public class ActionAttributeDemoTest : ITempDirectoryTest
{
    public string TemporaryDirectoryToStoreTestData { get; set; }

    [Test]
    public void ITempDirectoryTest_ImplementsInterface_TemporaryDirectoryIsCreatedAutomatically()
    {
        Assert.That(Directory.Exists(TemporaryDirectoryToStoreTestData), Is.True);
    }
}

ITempDirectoryTest.cs

/// <summary>
///     Attaching this interface to a NUnit test class provides access
///     to a temporary directory. The directory is created and deleted
///     automatically for each test case.
/// </summary>
[TempDirectoryAwareAction]
public interface ITempDirectoryTest
{
  string TemporaryDirectoryToStoreTestData { get; set; }
}

TempDirectoryAwareActionAttribute.cs

using System.IO;
using NUnit.Framework;

namespace SentryIntegration.TestCommon.NUnit.Actions
{
  public class TempDirectoryAwareActionAttribute : TestActionAttribute
  {
    private DirectoryInfo tempDirectoryToStoreTestData;

    public override ActionTargets Targets
    {
      get { return ActionTargets.Test; }
    }

    public override void BeforeTest(TestDetails details)
    {
      var tempDirectoryTest = details.Fixture as ITempDirectoryTest;
      if (tempDirectoryTest == null)
      {
        return;
      }

      CreateTemporaryDirectoryAndAssignToTest(tempDirectoryTest);
    }

    public override void AfterTest(TestDetails testDetails)
    {
      if (tempDirectoryToStoreTestData != null)
      {
        tempDirectoryToStoreTestData.Delete(true);
      }
    }

    private void CreateTemporaryDirectoryAndAssignToTest(ITempDirectoryTest tempDirectoryTest)
    {
      tempDirectoryToStoreTestData = CreateTemporaryDirectory();
      tempDirectoryTest.TemporaryDirectoryToStoreTestData = tempDirectoryToStoreTestData.FullName;
    }

    private static DirectoryInfo CreateTemporaryDirectory()
    {
      var tempFile = Path.GetTempFileName();
      File.Delete(tempFile);
      return Directory.CreateDirectory(tempFile);
    }
  }
}