Submitting changes after session 5

Added starting and ending Principal methods and changed withdraw method to track the total withdrawn amount.

Author: javierLiarte

scratchpad.txt

@@ -1,3 +1,5 @@
 Capital gains
 
-get rid of SavingsAccountYear initializers
+get rid of SavingsAccountYear initializers
+
+clean up _SavingsAccountYearTest

src/info/javierliarte/letsPlayTDD/finances/SavingsAccountYear.java

@@ -5,6 +5,7 @@ public class SavingsAccountYear {
 	private int startingBalance = 0;
 	private int capitalGainsAmount = 0;
 	private int interestRate = 0;
+	private int totalWithdrawn = 0;
 
 	public SavingsAccountYear(int startingBalance, int interestRate) {
 		this.startingBalance = startingBalance;
@@ -21,20 +22,32 @@ public int startingBalance() {
 		return startingBalance;
 	}
 
+
+	public int startingPrincipal() {
+		return startingBalance - capitalGainsAmount;
+	}
+
+
+	public int endingPrincipal() {
+		int result = startingPrincipal() - totalWithdrawn;
+		return (result < 0) ? 0 : result;
+	}
+
 	public int interestRate() {
 		return interestRate;
 	}
 
 	public int endingBalance() {
-		return startingBalance * (100 + interestRate) /100;
+		int modifiedStart = startingBalance - totalWithdrawn;
+		return modifiedStart * (100 + interestRate) /100;
 	}
 
 	public SavingsAccountYear nextYear() {
 		return new SavingsAccountYear(this.endingBalance(),this.interestRate);
 	}
 
 	public void withdraw(int amount) {
-		startingBalance -= amount;
+		this.totalWithdrawn += amount;
 	}
 
 }

src/info/javierliarte/letsPlayTDD/finances/_SavingsAccountYearTest.java

@@ -40,14 +40,44 @@ public void withdrawingFundsOccursAtTheBeginningOfTheYear() {
 	}
 
 	@Test
-	public void withdrawingMoreThanPrincipalInccursCapitalGainsTax() {
-		SavingsAccountYear year = new SavingsAccountYear(10000, 7000, 10);
-		year.withdraw(3000);
+	public void multipleWithdrawalsInAYear () {
+		SavingsAccountYear year = new SavingsAccountYear(10000, 10);
+		year.withdraw(1000);
+		year.withdraw(2000);
 		assertEquals(7700, year.endingBalance());
-		year.withdraw(5000);
-		assertEquals(2000 + 200 - (1250), year.endingBalance());
-		
 	}
+
+	@Test
+	public void principal() {
+		SavingsAccountYear year = new SavingsAccountYear(10000, 7000, 10);
+		assertEquals (3000, year.startingPrincipal());
+	}
+	
+	@Test
+	public void endingPrincipal() {
+		SavingsAccountYear year = new SavingsAccountYear(10000, 7000, 10);
+		assertEquals ("Starting principal", 3000, year.startingPrincipal());
+		year.withdraw(2000);
+		assertEquals ("Ending principal", 1000, year.endingPrincipal());
+	}
+	
+	@Test
+	public void endingPrincipalNeverGoesBelowZero() {
+		SavingsAccountYear year = new SavingsAccountYear(10000, 7000, 10);
+		assertEquals ("Starting principal", 3000, year.startingPrincipal());
+		year.withdraw(4000);
+		assertEquals("ending principal", 0, year.endingPrincipal());
+	}
+	
+//	@Test
+//	public void withdrawingMoreThanPrincipalInccursCapitalGainsTax() {
+//		SavingsAccountYear year = new SavingsAccountYear(10000, 7000, 10);
+//		year.withdraw(3000);
+//		assertEquals(7700, year.endingBalance());
+//		year.withdraw(5000);
+//		assertEquals(2000 + 200 - (1250), year.endingBalance());
+//		
+//	}
 
 	private SavingsAccountYear newAccount() {
 		SavingsAccountYear account = new SavingsAccountYear(10000, 10);