Exercise: Implement shop functions
Implement the following functions:
getWaitingCustomersthat returns the list of customers who ordered products that have not been delivered yet.countProductSalesthat returns the number of times a given product was ordered.getWaitingCustomersthat returns the list of customers who made orders with total price greater than or equal to the given amount.
Starting code:
fun Shop.getWaitingCustomers(): List<Customer> = TODO()
fun Shop.countProductSales(product: Product): Int = TODO()
fun Shop.getCustomers(
minAmount: Double,
): List<Customer> = TODO()
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
)
This problem can either be solved in the below playground or you can clone kotlin-exercises project and solve it locally. In the project, you can find code template for this exercise in functional/collections/Shop.kt. You can find there starting code and unit tests.
Once you are done with the exercise, you can check your solution here.
Playground
import org.junit.Test
import kotlin.test.assertEquals
fun Shop.getWaitingCustomers(): List<Customer> = TODO()
fun Shop.countProductSales(product: Product): Int = TODO()
fun Shop.getCustomers(
minAmount: Double,
): List<Customer> = TODO()
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))
}
}
