Basic C# Unit Tests

Sample.Tests.cs

using System;
using BankAccountNS;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace BankTest
{
    [TestClass]  // Tests are set in test classes...
    public class BankAccountTests
    {
        [TestMethod] // ... and test methods
        public void Debit_WithValidAmount_UpdatesBalance()
        {
            double beginningBalance = 11.99;
            double debitAmount = 4.55;
            double expected = 7.44;
            BankAccount account = new BankAccount("Mr. Jeremy Wells", beginningBalance);  // set up the class to test

            account.Debit(debitAmount);

            double actual = account.Balance;
            Assert.AreEqual(expected, actual, 0.001, "Account not debited correctly");  // assert equal, also indicate precision and message
        }
        [TestMethod]
        public void Debit_WhenAmountLessThanZero_ShouldThrowArgumentOutOfRange()
        {
            double beginningBalance = 11.999;
            double debitAmount = -100;
            BankAccount account = new BankAccount("Mr. Jeremy Wells", beginningBalance);

            try
            {
                account.Debit(debitAmount);
            }
            catch (ArgumentOutOfRangeException e)
            {
                StringAssert.Contains(e.Message, BankAccount.DebitAmountLessThanZeroMessage);  // make sure exception message matches specified message
            }
        }
        [TestMethod]
        public void Debit_WithAmountExceedingBalance_ShouldThrowArgumentOutOfRange()
        {
            double beginningBalance = 11.99;
            double debitAmount = 100;
            BankAccount account = new BankAccount("Mr. Jeremy Wells", beginningBalance);

            try
            {
                account.Debit(debitAmount);
            }
            catch (ArgumentOutOfRangeException e)
            {
                StringAssert.Contains(e.Message, BankAccount.DebitAmountExceedsBalanceMessage);
                return;  // exit method if exception is thrown
            }
            Assert.Fail("No exception was thrown");  // fail if no exception is thrown
        }
    }
}