using System;
using NUnit.Framework;
using NUnit.Extensions.Forms; 

namespace NUnitFormsTests
{
	/// <summary>
	/// Summary description for Class1.
	/// </summary>
	[TestFixture]
	public class FormTests : NUnit.Extensions.Forms.NUnitFormsAssertTest
	{
		private string nextExpectedModal = ""; 
		private bool useHidden = true; 
		private TargetForm.Form1 testForm = null; 
		private System.Random rnd = new Random(); 

		public FormTests()
		{
		}
		[Test]
		public void FormCreate()
		{
			LaunchForm1(); 
			Assert.AreEqual("Test Form", testForm.Text); 
		}
		[Test]
		public void ButtonMessageBoxClick()
		{
			LaunchForm1(); 
			ButtonTester bt = new ButtonTester("btnTest", testForm); 
			nextExpectedModal = "Test Message Box"; 
			ExpectModal(nextExpectedModal, "OnModal_DismissMessageBox"); 
			bt.Click(); 
			nextExpectedModal = string.Empty; 
		}
		[Test]
		public void ButtonChangeTextClick()
		{
			LaunchForm1(); 
			ButtonTester bt = new ButtonTester("btnChangeText", testForm); 
			bt.Click(); 
			NUnit.Extensions.Forms.TextBoxTester tbt = new TextBoxTester("txtTestField", testForm); 
			Assert.AreEqual("New Value",tbt.Text); 
		}
		[Test]
		public void LabelTest()
		{
			LaunchForm1(); 
			NUnit.Extensions.Forms.LabelTester lt = new LabelTester("lblTestField", testForm); 
			Assert.AreEqual("Test Field:", lt.Text); 
		}
		public void LaunchForm1()
		{		
			testForm = new TargetForm.Form1(); 
			testForm.Show();
		}
        private void OnModal_DismissMessageBox()
		{
			System.Threading.Thread.Sleep(rnd.Next(3000)); 
			NUnit.Extensions.Forms.MessageBoxTester mbt = new MessageBoxTester(nextExpectedModal); 
			mbt.ClickOk(); 
		}
		public override bool UseHidden
		{
			get
			{
				return useHidden; 
			}
		}
	}
}

Note:  The override of UseHidden controls whether or not NUnit will create forms in a hidden desktop/winstation.  It needs to be set before the constructor is called in order to be effective.

Using NUnitForms

C#