ShoppingCartTest.java

package com.example.shop;

import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.CsvSource;
import org.junit.jupiter.params.provider.ValueSource;

import static org.junit.jupiter.api.Assertions.*;

class ShoppingCartTest {
    @Test
    void addItem_returnsTrue_whenItemIsAdded() {
        ShoppingCart cart = new ShoppingCart();

        boolean result = cart.addItem("T-Shirt", 129.0, 1);

        assertTrue(result);
    }

    @Test
    void removeItem_returnsTrue_whenItemExists() {
        ShoppingCart cart = new ShoppingCart();
        cart.addItem("T-Shirt", 100.0, 1);

        boolean result = cart.removeItem("T-Shirt");

        assertTrue(result);
    }
    @Test
    void getTotalPrice_returnsSumOfPrices() {
        ShoppingCart cart = new ShoppingCart();

        cart.addItem("T-Shirt", 100.0, 2);
        cart.addItem("Jeans", 300, 1);

        assertEquals(500, cart.getTotalPrice());
    }
    @Test
    void updateQuantity_returnsTrue_andUpdatesTotalPrice() {
        ShoppingCart cart = new ShoppingCart();
        cart.addItem("T-Shirt", 100, 1);

        boolean result = cart.updateQuantity("T-Shirt", 3);
        assertTrue(result);
        assertEquals(300.0, cart.getTotalPrice());
    }
    @Test
    void applyDiscount_returnsTrue_andReducesTotal() {
        ShoppingCart cart = new ShoppingCart();
        cart.addItem("T-Shirt", 100.0, 1);
        boolean result = cart.applyDiscount(0.3);
        assertTrue(result);
        assertEquals(70.0, cart.getTotalPrice());
    }
    @Test
    void removeItemThatDoesNotExist_returnsFalse() {
        ShoppingCart cart = new ShoppingCart();

        Assertions.assertFalse(cart.removeItem("Hat"));
    }
    @Test
    void removeItemWhenNameIsNull_returnsFalse() {
        ShoppingCart cart = new ShoppingCart();
        Assertions.assertFalse(cart.removeItem(null));
    }
    @ParameterizedTest
    @CsvSource({
            "-1.0, 1",
            "10.0, -1",
            "10.0, 0",
            "-10.0, -1"
    })
    void addItemWithNegativePriceOrQty_returnsFalse(double price, int quantity) {
        ShoppingCart cart = new ShoppingCart();
        Assertions.assertFalse(cart.addItem("T-Shirt", price, quantity));
    }
    @Test
    void addItemWhereNameIsNull_returnsFalse() {
        ShoppingCart cart = new ShoppingCart();
        Assertions.assertFalse(cart.addItem(null, 100,1));
    }

    @Test
    void updateQuantityWhereNameIsNull_returnsFalse() {
        ShoppingCart cart = new ShoppingCart();
        Assertions.assertFalse(cart.updateQuantity(null, 1));
    }
    @ParameterizedTest
    @CsvSource({
            "-1",
            "0"
    })
    void updateQuantityWhereQtyIsNull_returnsFalse(int quantity) {
        ShoppingCart cart = new ShoppingCart();
        Assertions.assertFalse(cart.updateQuantity("T-Shirt",  quantity ));
    }

    @ParameterizedTest
    @CsvSource({
            "-0.1",
            "1.1"
    })
    void applyDiscountWhereDiscountIsNotAllowed_returnsFalse(double discount) {
        ShoppingCart cart = new ShoppingCart();
        Assertions.assertFalse(cart.applyDiscount(discount));
    }
}