[Samples][L7] Add UnitTests for the Account inheritance demo

Author: florinc

LessonsSamples/LessonsSamples/Lesson7/InheritanceComposition/Account.cs

@@ -2,10 +2,15 @@
 
 namespace LessonsSamples.Lesson7.InheritanceComposition
 {
-    class Account
+    public class Account
     {
         private decimal amount;
-        private decimal interestRate;
+        private readonly decimal interestRate;
+
+        public Account(decimal interestRate)
+        {
+            this.interestRate = interestRate;
+        }
 
         protected decimal CalculateTaxesForMoth(Month month)
 		{
@@ -16,7 +21,7 @@ protected decimal CalculateTaxesForMoth(Month month)
         public decimal Amount
         {
             get { return amount; }
-            protected set { amount = value; }
+            set { amount = value; }
         }
 
         public decimal MonthlyInterest()
@@ -37,6 +42,10 @@ public virtual void MonthlyRenewal()
 
 	class SavingsAccount : Account
     {
+        public SavingsAccount(decimal interestRate) : base(interestRate)
+        {
+        }
+
         public decimal YearlyProfit()
         {
 			// ... 
@@ -60,25 +69,33 @@ private decimal CalculateYearlyDeposits()
 
     class CheckingAccount : Account
     {
+        public CheckingAccount(decimal interestRate) : base(interestRate)
+        {
+        }
+
         public decimal TransactionsCosts()
         {
 			// ... 
 			Month lastMonth = new Month();
 			var lastMonthTaxes = CalculateTaxesForMoth(lastMonth);
-			decimal lastMonthCommissions = CalculateLastMonthCommision();
+			decimal lastMonthBankCharges = CalculateLastMonthBankCharges();
             // ... 
 
-            return lastMonthCommissions + lastMonthTaxes;
+            return lastMonthBankCharges + lastMonthTaxes;
         }
 
-        private decimal CalculateLastMonthCommision()
+        private decimal CalculateLastMonthBankCharges()
         {
             throw new NotImplementedException();
         }
     }
 
     class AutoLoanAccount : Account
     {
+        public AutoLoanAccount(decimal interestRate) : base(interestRate)
+        {
+        }
+
         public override void MonthlyRenewal()
         {
 	        decimal interest = MonthlyInterest();

LessonsSamples/LessonsSamples/Lesson7/InheritanceComposition/AccountClientCode.cs

@@ -2,7 +2,7 @@
 {
     static class AccountClientCode
     {
-        public static decimal CalculateTotalMonthlyInterest(Account[] accounts)
+        public static decimal CalculateTotalInterestValue(Account[] accounts)
         {
             decimal amount = 0;
             for (int i = 0; i < accounts.Length; i++)

LessonsSamples/LessonsSamples/Lesson7/InheritanceComposition/AccountClientCodeTests.cs

@@ -0,0 +1,36 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace LessonsSamples.Lesson7.InheritanceComposition
+{
+    [TestClass]
+    public class AccountClientCodeTests
+    {
+        [TestMethod]
+        public void CalculateTotalInterestValue_MoreAccounts_InterestSummedFromAll()
+        {
+            Account[] accounts =
+            {
+                new Account(50) {Amount = 1},   //+0.5
+                new Account(50) {Amount = 1},   //+0.5
+                new Account(50) {Amount = 1},   //+0.5
+            };
+            decimal actualInterest = AccountClientCode.CalculateTotalInterestValue(accounts);
+
+            Assert.AreEqual(1.5m, actualInterest);
+        }
+
+        [TestMethod]
+        public void CalculateTotalInterestValue_AllAccountTypes_InterestSummedFromAll()
+        {
+            Account[] accounts =
+            {
+                new SavingsAccount(50) {Amount = 1},   //+0.5
+                new CheckingAccount(50) {Amount = 1},  //+0.5
+                new AutoLoanAccount(50) {Amount = 1},  //-0.5
+            };
+            decimal actualInterest = AccountClientCode.CalculateTotalInterestValue(accounts);
+
+            Assert.AreEqual(0.5m, actualInterest);
+        }
+    }
+}

LessonsSamples/LessonsSamples/Lesson7/InheritanceComposition/AccountTests.cs

@@ -0,0 +1,48 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace LessonsSamples.Lesson7.InheritanceComposition
+{
+    [TestClass]
+    public abstract class AccountContractTests
+    {
+        [TestMethod]
+        public void MonthlyInterest_AmountIsPositive_InterestAppliedAsPercentage()
+        {
+            Account account = GetTarget(50);
+            account.Amount = 100;
+
+            decimal interest = account.MonthlyInterest();
+
+            Assert.AreEqual(50m, interest);
+        }
+
+        protected abstract Account GetTarget(decimal interestRate);
+    }
+
+    [TestClass]
+    public class SavingsAccountTests : AccountContractTests
+    {
+        protected override Account GetTarget(decimal interestRate)
+        {
+            return new SavingsAccount(interestRate);
+        }
+    }
+
+    [TestClass]
+    public class CheckingAccountTests : AccountContractTests
+    {
+        protected override Account GetTarget(decimal interestRate)
+        {
+            return new CheckingAccount(interestRate);
+        }
+    }
+
+    [TestClass]
+    public class AutoLoanAccountTests : AccountContractTests
+    {
+        protected override Account GetTarget(decimal interestRate)
+        {
+            return new AutoLoanAccount(interestRate);
+        }
+    }
+}

LessonsSamples/LessonsSamples/Lesson7/InheritanceComposition/Month.cs

@@ -1,6 +1,6 @@
 namespace LessonsSamples.Lesson7.InheritanceComposition
 {
-	internal struct Month
+    public struct Month
 	{
 		public int Year;
 		public int MonthOfYear;

LessonsSamples/LessonsSamples/LessonsSamples.csproj

@@ -206,6 +206,8 @@
     <Compile Include="Lesson7\ErrorHandling\CodeSnippet.cs" />
     <Compile Include="Lesson7\InheritanceComposition\Account.cs" />
     <Compile Include="Lesson7\InheritanceComposition\AccountClientCode.cs" />
+    <Compile Include="Lesson7\InheritanceComposition\AccountClientCodeTests.cs" />
+    <Compile Include="Lesson7\InheritanceComposition\AccountTests.cs" />
     <Compile Include="Lesson7\InheritanceComposition\ILogMessageParser.cs" />
     <Compile Include="Lesson7\InheritanceComposition\LogEntry.cs" />
     <Compile Include="Lesson7\InheritanceComposition\LogSource.cs" />