Solution: Inventory management
class Inventory {
private val products = mutableListOf<Product>()
private val productIdToProducer =
mutableMapOf<String, String>()
private val sellers = mutableSetOf<String>()
fun addProduct(product: Product, producer: String) {
products.add(product)
productIdToProducer[product.id] = producer
}
fun removeProduct(product: Product) {
products.remove(product)
productIdToProducer.remove(product.id)
}
fun addSeller(seller: String) {
sellers.add(seller)
}
fun removeSeller(seller: String) {
sellers.remove(seller)
}
fun getProductsCount() = products.size
fun hasProduct(product: Product) =
products.contains(product)
fun hasProducts() = products.isNotEmpty()
fun getProducer(product: Product) =
productIdToProducer[product.id]
fun produceInventoryDisplay(): String {
var result = "Inventory:\n"
for (product in products) {
val name = product.name
val category = product.category
val price = product.price
result += "$name ($category) - $price\n"
val producer = productIdToProducer[product.id]
result += "Produced by: $producer\n"
}
result += "Sellers: $sellers"
return result
}
}
Example solution in playground
import junit.framework.TestCase.*
import org.junit.Before
import org.junit.Test
import kotlin.test.assertEquals
class Inventory {
private val products = mutableListOf<Product>()
private val productIdToProducer =
mutableMapOf<String, String>()
private val sellers = mutableSetOf<String>()
fun addProduct(product: Product, producer: String) {
products.add(product)
productIdToProducer[product.id] = producer
}
fun removeProduct(product: Product) {
products.remove(product)
productIdToProducer.remove(product.id)
}
fun addSeller(seller: String) {
sellers.add(seller)
}
fun removeSeller(seller: String) {
sellers.remove(seller)
}
fun getProductsCount() = products.size
fun hasProduct(product: Product) =
products.contains(product)
fun hasProducts() = products.isNotEmpty()
fun getProducer(product: Product) =
productIdToProducer[product.id]
fun produceInventoryDisplay(): String {
var result = "Inventory:\n"
for (product in products) {
val name = product.name
val category = product.category
val price = product.price
result += "$name ($category) - $price\n"
val producer = productIdToProducer[product.id]
result += "Produced by: $producer\n"
}
result += "Sellers: $sellers"
return result
}
}
class Product(
val id: String,
val name: String,
val price: Double,
val category: String,
)
fun main() {
val inventory = Inventory()
println(inventory.hasProducts()) // false
val p1 = Product("P1", "Phone", 599.99, "Electronics")
val p2 = Product("P2", "Laptop", 1199.99, "Electronics")
val p3 = Product("P3", "Shirt", 29.99, "Clothing")
inventory.addProduct(p1, "TechCompany")
inventory.addProduct(p2, "TechCompany")
inventory.addProduct(p3, "ClothingCompany")
inventory.addSeller("Seller1")
inventory.addSeller("Seller2")
println(inventory.getProductsCount()) // 3
println(inventory.hasProduct(p1)) // true
println(inventory.hasProducts()) // true
println(inventory.getProducer(p1)) // TechCompany
println(inventory.produceInventoryDisplay())
// Inventory:
// Phone (Electronics) - $599.99
// Produced by: TechCompany
// Laptop (Electronics) - $1199.99
// Produced by: TechCompany
// Shirt (Clothing) - $29.99
// Produced by: ClothingCompany
// Sellers: [Seller1, Seller2]
inventory.removeProduct(p2)
inventory.addSeller("Seller1")
inventory.removeSeller("Seller2")
println(inventory.getProductsCount()) // 2
println(inventory.hasProduct(p1)) // true
println(inventory.hasProduct(p2)) // false
println(inventory.hasProducts()) // true
println(inventory.getProducer(p2)) // null
println(inventory.produceInventoryDisplay())
// Inventory:
// Phone (Electronics) - $599.99
// Produced by: TechCompany
// Shirt (Clothing) - $29.99
// Produced by: ClothingCompany
// Sellers: [Seller1]
}
class InventoryTest {
private lateinit var inventory: Inventory
private val apple = Product("1", "Apple", 0.5, "Fruit")
private var banana = Product("2", "Banana", 0.3, "Fruit")
@Before
fun setup() {
inventory = Inventory()
}
@Test
fun `addProduct should increase product count and set producer`() {
inventory.addProduct(apple, "FruitCorp")
assertEquals(1, inventory.getProductsCount())
assertTrue(inventory.hasProduct(apple))
assertEquals("FruitCorp", inventory.getProducer(apple))
}
@Test
fun `removeProduct should decrease product count and remove producer`() {
inventory.addProduct(apple, "FruitCorp")
inventory.removeProduct(apple)
assertEquals(0, inventory.getProductsCount())
assertFalse(inventory.hasProduct(apple))
assertNull(inventory.getProducer(apple))
}
@Test
fun `addSeller should add seller to the inventory`() {
inventory.addSeller("SellerA")
assertTrue(inventory.produceInventoryDisplay().contains("SellerA"))
}
@Test
fun `removeSeller should remove seller from the inventory`() {
inventory.addSeller("SellerA")
inventory.removeSeller("SellerA")
assertFalse(inventory.produceInventoryDisplay().contains("SellerA"))
}
@Test
fun `produceInventoryDisplay should display products and sellers correctly`() {
inventory.addProduct(apple, "FruitCorp")
inventory.addProduct(banana, "TropicalFruitCorp")
inventory.addSeller("SellerA")
inventory.addSeller("SellerB")
val expectedDisplay = """
Inventory:
Apple (Fruit) - 0.5
Produced by: FruitCorp
Banana (Fruit) - 0.3
Produced by: TropicalFruitCorp
Sellers: [SellerA, SellerB]
""".trimIndent()
assertEquals(expectedDisplay, inventory.produceInventoryDisplay())
}
@Test
fun `hasProducts should return true when there are products`() {
inventory.addProduct(apple, "FruitCorp")
assertTrue(inventory.hasProducts())
}
@Test
fun `hasProducts should return false when there are no products`() {
assertFalse(inventory.hasProducts())
}
@Test
fun `getProducer should return null for nonexistent product`() {
assertNull(inventory.getProducer(apple))
}
}
