Learn UnitTest in .Net

You want to write unit test for any class. Following are the attributes you need to write a unit test.

Mandatory:
1 - TestClass - This attribute identifies that attributed class is a test class.
2 - TestMethod - This attribute identifies that the attributed method is a test method in the test class.

3 - TestInitialize: This attributed method runs before the every test method.
4 - TestCleanup: This attributed method runs after the every test method.
5 - ClassInitialize: This attributed method runs once when the unit test class is initialized. Normally it can be used when we perform DB seeding or mocking objects globally.
6 - ClassCleanup: This attributed method runs once when the unit test class has run all the test methods. It can be used when the data inserted needs to be rollback.
7 - TestCategory: When the group of classes need to executed simultaneously or in a one go then on the class this attributed is binded with any name. e.g. Financials or something else.
How to group module unit test classes.
8 -ExpectedException: When any function raise any exception then this attribute can be used.

Here's a snippet of a code that will show the above attributes.

//A business class that performs add operation.
public class Maths
   {
      public int Add(int a, int b)
      {
         return checked(a + b);
      }
   }


// A test class that checks the functionality of the business class Maths.
   [TestClass]
   public class UnitTest1
   {
      Maths obj = new Maths();
      
      [TestInitialize] // you can use ClassInitialize attribute. 
      public void Setup()
      {
         System.Diagnostics.Debug.WriteLine("In a child debug ");
      }

      [TestCleanup] // you can use ClassCleanup attribute.
      public void Cleanup()
      {
             obj.Dispose();
      }
//// A test method.
      [TestMethod]
      public void TestMethod12()
      {
         Assert.IsTrue(obj.Add(2, 3) == 5);  
      }
/// A test method that shows exception checking.
      [TestMethod]
      [ExpectedException(typeof(OverflowException))]
      public void TestOverflowException()
      {
         int i = obj.Add(int.MaxValue, int.MaxValue);
      }
   }

Verification of the Function return values.
There are some classes in the unit testing framework from which you can test your expectations or actual result.

1 - Assert - Description of the methods in this class are here
2 - CollectionAssert - Description of the methods in this class are here 

You can check here to get more detail and more attributes about this testing framework.