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Java Unit Testing in Java What to Test Test the running total

Jim Sweeney
Jim Sweeney
3,050 Points

Can someone help on JUnit testing where total sales increment after a sale?

I originally thought that if I set amounts for the price of the item being sold and the amount of the pre-existing amount. I could then assertEquals with that and the actual method but I can't seem to get it right. Please help.

com/teamtreehouse/vending/VendingMachineTest.java
package com.teamtreehouse.vending;

import org.junit.Before;
import org.junit.Test;

import static org.junit.Assert.*;

public class VendingMachineTest {
    private VendingMachine machine;

    public class NotifierSub implements Notifier {

        @Override
        public void onSale(Item item) {
            return;
        }
    }

    @Before
    public void setUp() throws Exception {
        Notifier notifier = new NotifierSub();
        machine = new VendingMachine(notifier, 10, 10, 10);
        machine.restock("A1", "Twinkies", 10, 30, 75);
    }

    @Test
    public void vendingWhenStockedReturnsItem() throws Exception {
        machine.addMoney(75);

        Item item = machine.vend("A1");

        assertEquals("Twinkies", item.getName());
    }
    @Test
    public void successfulVendIncrementsSalesTotal() throws Exception {

        machine.vend("Twinkies");
        price = 75;
        runningSalesTotal = 100;
        int Total = machine.runningSalesTotal;

        assertEquals(175, Total);

    }
}
com/teamtreehouse/vending/VendingMachine.java
package com.teamtreehouse.vending;


public class VendingMachine {
    private final Notifier notifier;
    private final AbstractChooser chooser;
    private final Creditor creditor;
    private final Bin[][] bins;
    private int runningSalesTotal;

    public VendingMachine(Notifier notifier, int rowCount, int columnCount, int maxItemsPerBin) {
        this.notifier = notifier;
        chooser = new AlphaNumericChooser(rowCount, columnCount);
        creditor = new Creditor();
        runningSalesTotal = 0;
        bins = new Bin[rowCount][columnCount];
        for (int row = 0; row < rowCount; row++) {
            for (int col = 0; col < columnCount; col++) {
                bins[row][col] = new Bin(maxItemsPerBin);
            }
        }
    }

    public void addMoney(int money) {
        creditor.addFunds(money);
    }

    public int refundMoney() {
        return creditor.refund();
    }

    public Item vend(String input) throws InvalidLocationException, NotEnoughFundsException {
        Bin bin = binByInput(input);
        int price = bin.getItemPrice();
        creditor.deduct(price);
        runningSalesTotal += price;
        Item item = bin.release();
        notifier.onSale(item);
        return item;
    }

    public int getRunningSalesTotal() {
        return runningSalesTotal;
    }

    public void restock(String input, String name, int amount, int wholesalePrice, int retailPrice) throws InvalidLocationException {
        Bin bin = binByInput(input);
        bin.restock(name, amount, wholesalePrice, retailPrice);
    }

    private Bin binByInput(String input) throws InvalidLocationException {
        AbstractChooser.Location location = chooser.locationFromInput(input);
        return bins[location.getRow()][location.getColumn()];
    }

}

1 Answer

Seth Kroger
Seth Kroger
56,392 Points

You can't refer to an object's fields without referring to the object itself first. Also, these fields are private so you can't access them directly. You'll need to use the provided getters/setters and other methods for this.

Try to think of this in terms of the 3 A's (arrange/act/assert). Arrange: machine is set up, we put money in the machine. Act: we get a twinkie (hint: through the machine's keypad). Assert: check that the running total is what we expect it should be.