Advanced Unit Testing, Part II - Core Implementation

using System;

using System.Diagnostics;
using System.Drawing;

using NUnit.Framework;

// NUnit requires that test methods be public
// NUnit calls TearDown before calling SetUp!!!

namespace NUnitExample
{
	[TestFixture]
	public class TestExample
	{
		private ClassBeingTested cbt=null;

		[SetUp]
		public void Initialize()
		{
			Trace.WriteLine("SetUp");
			cbt=new ClassBeingTested();
		}

		[TearDown]
		public void Terminate()
		{
			Trace.WriteLine("TearDown");
			if (cbt != null)
			{
				cbt.Dispose();
			}
		}

		[Test]
		public void DoATest()
		{
			Trace.WriteLine("DoATest");
			cbt.LoadImage("fish.jpg");
		}

		[Test, Ignore("Reason")]
		public void IgnoreThisTest()
		{
			Trace.WriteLine("IgnoreThisTest");
		}

		[Test, ExpectedException(typeof(Exception))]
		public void ThrowAnException()
		{
			Trace.WriteLine("ThrowAnException");
			throw new Exception("an exception");
		}
	}

	public class ClassBeingTested : IDisposable
	{
		private bool disposed=false;
		private Image img=null;

		// the constructor
		public ClassBeingTested()
		{
			Trace.WriteLine("ClassBeingTested: Constructor");
		}

		// the destructor
		~ClassBeingTested()
		{
			Trace.WriteLine("ClassBeingTested: Destructor");
			// call Dispose with false.  Since we're in the
			// destructor call, the managed resources will be
			// disposed of anyways.
			Dispose(false);
		}

		public void Dispose()
		{
			Trace.WriteLine("ClassBeingTested: Dispose");
			// dispose of the managed and unmanaged resources
			Dispose(true);

			// tell the GC that the Finalize process no longer needs
			// to be run for this object.
			GC.SuppressFinalize(this);
		}

		protected virtual void Dispose(bool disposeManagedResources)
		{
			// process only if mananged and unmanaged resources have
			// not been disposed of.
			if (!this.disposed)
			{
				Trace.WriteLine("ClassBeingTested: Resources not disposed");
				if (disposeManagedResources)
				{
					Trace.WriteLine("ClassBeingTested: Disposing managed resources");
					// dispose managed resources
					if (img != null)
					{
						img.Dispose();
					}
				}
				// dispose unmanaged resources
				Trace.WriteLine("ClassBeingTested: Disposing unmanaged resouces");
				disposed=true;
			}
			else
			{
				Trace.WriteLine("ClassBeingTested: Resources already disposed");
			}
		}

		// loading an image
		public void LoadImage(string file)
		{
			Trace.WriteLine("ClassBeingTested: LoadImage");
			img=Image.FromFile(file);
		}
	}
}