Solution: Implementing the Product class
class Product(
val name: String,
val price: Double,
initialQuantity: Int
) {
var quantity: Int = initialQuantity
set(value) {
field = if (value >= 0) value else 0
}
fun calculateTotalValue(): Double {
return price * quantity
}
fun restock(additionalQuantity: Int) {
if (additionalQuantity > 0) {
quantity += additionalQuantity
}
}
}
Example solution in playground
import org.junit.Test
import kotlin.test.assertEquals
class Product(
val name: String,
val price: Double,
initialQuantity: Int
) {
var quantity: Int = initialQuantity
set(value) {
field = if (value >= 0) value else 0
}
fun calculateTotalValue(): Double {
return price * quantity
}
fun restock(additionalQuantity: Int) {
if (additionalQuantity > 0) {
quantity += additionalQuantity
}
}
}
fun main() {
val laptop = Product("Laptop", 999.99, 5)
println(laptop.name) // Laptop
println(laptop.quantity) // 5
println(laptop.calculateTotalValue()) // 4999.95
laptop.restock(3)
println(laptop.quantity) // 8
println(laptop.calculateTotalValue()) // 7999.92
laptop.quantity = -2
println(laptop.quantity) // 0
println(laptop.calculateTotalValue()) // 0.0
laptop.quantity = 10
println(laptop.quantity) // 10
println(laptop.calculateTotalValue()) // 9999.9
}
class ProductTest {
@Test
fun `should keep name, price and quantity`() {
val product = Product("Apple", 1.0, 10)
assertEquals("Apple", product.name)
assertEquals(1.0, product.price)
assertEquals(10, product.quantity)
}
@Test
fun `should calculate total value`() {
assertEquals(10.0, Product("Apple", 1.0, 10).calculateTotalValue())
assertEquals(0.0, Product("Apple", 1.0, 0).calculateTotalValue())
assertEquals(0.0, Product("Apple", 0.0, 10).calculateTotalValue())
assertEquals(3.6, Product("Apple", 1.2, 3).calculateTotalValue())
}
@Test
fun `should restock`() {
val product = Product("Apple", 1.0, 10)
product.restock(5)
assertEquals(15, product.quantity)
product.restock(-5)
assertEquals(15, product.quantity)
product.restock(0)
assertEquals(15, product.quantity)
}
@Test
fun `should not allow negative quantity`() {
val product = Product("Apple", 1.0, 10)
product.quantity = -5
assertEquals(0, product.quantity)
product.quantity = 8
assertEquals(8, product.quantity)
product.quantity = 0
assertEquals(0, product.quantity)
}
}
