FlowerDeliveryServiceTest.kt

package com.revolut.interview.service.impl

import com.revolut.interview.Address
import com.revolut.interview.Box
import com.revolut.interview.Flower
import com.revolut.interview.FlowerDelivery
import org.junit.jupiter.api.Assertions.assertTrue
import org.junit.jupiter.api.BeforeEach
import org.junit.jupiter.api.Test
import org.junit.jupiter.api.assertThrows

class FlowerDeliveryServiceTest {

    internal lateinit var flowerDeliveryService: FlowerDelivery

    @BeforeEach
    fun init() {
        flowerDeliveryService = FlowerDelivery()
    }

    @Test
    fun `negative test throws IllegalStateException on empty addresses or flowers`() {
        val addresses = listOf(
            Address("first"),
            Address("second")
        )
        val flowers = listOf(
            Flower(1, "color"),
            Flower(2, "color"),
            Flower(3, "color")
        )
        assertThrows<IllegalStateException> { flowerDeliveryService.distribute(emptyList(), flowers) }
        assertThrows<IllegalStateException> { flowerDeliveryService.distribute(addresses, emptyList()) }
    }

    @Test
    fun `negative test throws IllegalArgumentException on addresses more than flowers`() {
        val addresses = listOf(
            Address("first"),
            Address("second")
        )
        val flowers = listOf(
            Flower(1, "color")
        )
        assertThrows<IllegalArgumentException> { flowerDeliveryService.distribute(addresses, flowers) }
    }

    @Test
    fun `negative test throws IllegalStateException on non unique flowers`() {
        val addresses = listOf(
            Address("first"),
            Address("second")
        )
        val flowers = listOf(
            Flower(1, "color"),
            Flower(1, "color")
        )
        assertThrows<IllegalStateException> { flowerDeliveryService.distribute(addresses, flowers) }
    }

    @Test
    fun `test each box get unique color flower`() {
        val boxes = flowerDeliveryService.distribute(
            addresses = listOf(
                Address("address_1"),
                Address("address_2"),
                Address("address_3")
            ),

            flowers = listOf(
                Flower(1, "color_1"),
                Flower(2, "color_2"),
                Flower(3, "color_3")
            )
        )
        checkBoxes(boxes)
    }

    @Test
    fun `test each box get single color flower`() {
        val boxes = flowerDeliveryService.distribute(
            addresses = listOf(
                Address("address_1"),
                Address("address_2"),
                Address("address_3")
            ),

            flowers = listOf(
                Flower(1, "color_1"),
                Flower(2, "color_1"),
                Flower(3, "color_1")
            )
        )
        checkBoxes(boxes)
    }

    @Test
    fun `compound test each box get unique color flower`() {
        val boxes = flowerDeliveryService.distribute(
            listOf(
                Address("address_1"),
                Address("address_2"),
                Address("address_3")
            ),
            listOf(
                Flower(1, "color_1"),
                Flower(2, "color_2"),
                Flower(3, "color_3"),

                Flower(4, "color_1"),
                Flower(5, "color_2"),
                Flower(6, "color_3")
            )
        )

        checkBoxes(boxes)
    }

    private fun checkBoxes(boxes: List<Box>) {
        println("Checking boxes:\n" + boxes.asString())

        val eachBoxHasFlowers = boxes.all { it.flowers.isNotEmpty() }
        assertTrue(eachBoxHasFlowers)

        for ((index, box) in boxes.withIndex()) {
            val flowerColors = box.flowers.map { it.color }
            val uniqueColorFlowers = flowerColors.distinct()

            val boxHasOnlyUniqueColorFlowers = (uniqueColorFlowers.size - flowerColors.size) == 0
            assertTrue(boxHasOnlyUniqueColorFlowers) { "Box #$index has non unique colors: ${flowerColors - uniqueColorFlowers}" }
        }
    }

    private fun List<Box>.asString(): String = joinToString(separator = "\n") { box -> box.asString() }

    private fun Box.asString(): String = "" + address + flowers.joinToString(prefix = "[", postfix = "]") { "(${it.id}, ${it.color})" }
}