Solution: Implement shop functions
fun Shop.getWaitingCustomers(): List<Customer> = customers
.filter { it.orders.any { !it.isDelivered } }
fun Shop.countProductSales(product: Product): Int = customers
.flatMap { it.orders }
.flatMap { it.products }
.count { it == product }
// or (with better performance)
// .sumOf {
// it.orders.sumOf {
// it.products.count { it == product }
// }
// }
fun Shop.getCustomers(minAmount: Double): List<Customer> =
customers.filter {
it.orders.sumOf {
it.products.sumOf { it.price }
} >= minAmount
}
Example solution in playground
import org.junit.Test
import kotlin.test.assertEquals
fun Shop.getWaitingCustomers(): List<Customer> = customers
.filter { it.orders.any { !it.isDelivered } }
fun Shop.countProductSales(product: Product): Int = customers
.flatMap { it.orders }
.flatMap { it.products }
.count { it == product }
// or (with better performance)
// .sumOf {
// it.orders.sumOf {
// it.products.count { it == product }
// }
// }
fun Shop.getCustomers(minAmount: Double): List<Customer> =
customers.filter {
it.orders.sumOf {
it.products.sumOf { it.price }
} >= minAmount
}
data class Shop(
val name: String,
val customers: List<Customer>
)
data class Customer(
val name: String,
val city: City,
val orders: List<Order>
)
data class Order(
val products: List<Product>,
val isDelivered: Boolean
)
data class Product(
val name: String,
val price: Double
)
data class City(
val name: String
)
class ShopFunctionsTests {
@Test
fun `getWaitingCustomers should get customers with any delivered order`() {
// given
val shop = Shop(
name = "Test shop",
customers = listOf(
Customer(
name = "Customer 1",
city = City("City 1"),
orders = listOf(
Order(
products = listOf(
Product("Product 1", 1.0),
Product("Product 2", 2.0),
),
isDelivered = true,
),
Order(
products = listOf(
Product("Product 3", 3.0),
Product("Product 4", 4.0),
),
isDelivered = false,
),
),
),
Customer(
name = "Customer 2",
city = City("City 2"),
orders = listOf(
Order(
products = listOf(
Product("Product 5", 5.0),
Product("Product 6", 6.0),
),
isDelivered = true,
),
Order(
products = listOf(
Product("Product 7", 7.0),
Product("Product 8", 8.0),
),
isDelivered = true,
),
),
),
),
)
// when
val result = shop.getWaitingCustomers()
// then
val expected = listOf(
Customer(
name = "Customer 1",
city = City("City 1"),
orders = listOf(
Order(
products = listOf(
Product("Product 1", 1.0),
Product("Product 2", 2.0),
),
isDelivered = true,
),
Order(
products = listOf(
Product("Product 3", 3.0),
Product("Product 4", 4.0),
),
isDelivered = false,
),
),
),
)
assertEquals(expected, result)
}
@Test
fun `getWaitingCustomers should not return customers with no orders`() {
// given
val shop = Shop(
name = "Test shop",
customers = listOf(
Customer(
name = "Customer 1",
city = City("City 1"),
orders = listOf(
Order(
products = listOf(
Product("Product 1", 1.0),
Product("Product 2", 2.0),
),
isDelivered = true,
),
Order(
products = listOf(
Product("Product 3", 3.0),
Product("Product 4", 4.0),
),
isDelivered = false,
),
),
),
Customer(
name = "Customer 2",
city = City("City 2"),
orders = listOf(),
),
),
)
// when
val result = shop.getWaitingCustomers()
// then
val expected = listOf(
Customer(
name = "Customer 1",
city = City("City 1"),
orders = listOf(
Order(
products = listOf(
Product("Product 1", 1.0),
Product("Product 2", 2.0),
),
isDelivered = true,
),
Order(
products = listOf(
Product("Product 3", 3.0),
Product("Product 4", 4.0),
),
isDelivered = false,
),
),
),
)
assertEquals(expected, result)
}
@Test
fun `getWaitingCustomers should not return customers all orders delivered`() {
// given
val shop = Shop(
name = "Test shop",
customers = listOf(
Customer(
name = "Customer 1",
city = City("City 1"),
orders = listOf(
Order(
products = listOf(
Product("Product 1", 1.0),
Product("Product 2", 2.0),
),
isDelivered = true,
),
Order(
products = listOf(
Product("Product 3", 3.0),
Product("Product 4", 4.0),
),
isDelivered = true,
),
),
),
Customer(
name = "Customer 2",
city = City("City 2"),
orders = listOf(
Order(
products = listOf(
Product("Product 5", 5.0),
Product("Product 6", 6.0),
),
isDelivered = true,
),
Order(
products = listOf(
Product("Product 7", 7.0),
Product("Product 8", 8.0),
),
isDelivered = true,
),
),
),
),
)
// when
val result = shop.getWaitingCustomers()
// then
assertEquals(listOf(), result)
}
@Test
fun `countProductSales should count repeating sales`() {
// given
val p1 = Product("Product 1", 1.0)
val p2 = Product("Product 2", 2.0)
val p3 = Product("Product 3", 3.0)
val shop = Shop(
name = "Test shop",
customers = listOf(
Customer(
name = "Customer 1",
city = City("City 1"),
orders = listOf(
Order(
products = listOf(p1, p2),
isDelivered = true,
),
Order(
products = listOf(p1, p3),
isDelivered = false,
),
),
),
Customer(
name = "Customer 2",
city = City("City 2"),
orders = listOf(
Order(
products = listOf(p1, p1),
isDelivered = true,
),
Order(
products = listOf(p2, p3),
isDelivered = true,
),
),
),
),
)
// then
assertEquals(4, shop.countProductSales(p1))
assertEquals(2, shop.countProductSales(p2))
assertEquals(2, shop.countProductSales(p3))
}
@Test
fun `countProductSales should count sales with exactly the same product`() {
// given
val shop = Shop(
name = "Test shop",
customers = listOf(
Customer(
name = "Customer 1",
city = City("City 1"),
orders = listOf(
Order(
products = listOf(Product("Product 2", 1.0), Product("Product 1", 2.0)),
isDelivered = true,
),
),
),
),
)
// then
assertEquals(0, shop.countProductSales(Product("Product 1", 1.0)))
assertEquals(1, shop.countProductSales(Product("Product 2", 1.0)))
assertEquals(1, shop.countProductSales(Product("Product 1", 2.0)))
assertEquals(0, shop.countProductSales(Product("Product 2", 2.0)))
}
@Test
fun `getCustomers should get customers with orders with total price greater than minAmount`() {
// given
val p1 = Product("Product 1", 1.0)
val p2 = Product("Product 2", 2.0)
val p3 = Product("Product 3", 3.0)
val p4 = Product("Product 4", 4.0)
val p5 = Product("Product 5", 5.0)
val p6 = Product("Product 6", 6.0)
val p7 = Product("Product 7", 7.0)
val p8 = Product("Product 8", 8.0)
val c1 = Customer(
name = "Customer 1",
city = City("City 1"),
orders = listOf(
Order(
products = listOf(p1, p2),
isDelivered = true,
),
Order(
products = listOf(p1, p3),
isDelivered = false,
),
),
)
val c2 = Customer(
name = "Customer 2",
city = City("City 2"),
orders = listOf(
Order(
products = listOf(p1, p1),
isDelivered = true,
),
Order(
products = listOf(p2, p3),
isDelivered = true,
),
),
)
val c3 = Customer(
name = "Customer 3",
city = City("City 3"),
orders = listOf(
Order(
products = listOf(p4, p5),
isDelivered = true,
),
Order(
products = listOf(p6, p7),
isDelivered = true,
),
),
)
val c4 = Customer(
name = "Customer 4",
city = City("City 4"),
orders = listOf(
Order(
products = listOf(p8, p8),
isDelivered = true,
),
),
)
val shop = Shop(
name = "Test shop",
customers = listOf(c1, c2, c3, c4),
)
// then
assertEquals(listOf(c1, c2, c3, c4), shop.getCustomers(0.0))
assertEquals(listOf(c3, c4), shop.getCustomers(10.0))
assertEquals(listOf(c3), shop.getCustomers(20.0))
assertEquals(listOf(), shop.getCustomers(30.0))
}
}
