Redesign of decorator pattern

src/main/kotlin/Command/base/Cart.kt

@@ -1,14 +1,12 @@
 package Command.base
 
+import Decorator.littlekai.base.IngredientDecorator
 import Decorator.littlekai.base.Noodles
 import Decorator.littlekai.base.SauceDecorator
 import Decorator.littlekai.ingredients.Chicken
 import Decorator.littlekai.ingredients.Peanuts
 import Decorator.littlekai.ingredients.Pork
 import Decorator.littlekai.ingredients.Tuna
-import Decorator.littlekai.noodles.EggNoodles
-import Decorator.littlekai.noodles.UdonNoodles
-import Decorator.littlekai.noodles.WheatNoodles
 import Decorator.littlekai.sauces.BittersweetSauce
 import Decorator.littlekai.sauces.RedPepperSauce
 import Decorator.littlekai.sauces.SateSauce
@@ -79,7 +77,11 @@ open class Cart(private val scanner: Scanner) {
   }
 
   fun showPrice() {
-    println("> Your order is: ${noodles.calculateCost()} $")
+    var totalCost = noodles.calculateCost()
+    if (noodles is IngredientDecorator) {
+      totalCost = (noodles as IngredientDecorator).calculateTotalCost()
+    }
+    println("> Your order is: $totalCost $")
     if (noodles is SauceDecorator) {
       println("> Spiciness is: ${(noodles as SauceDecorator).SPICINESS} out of 4")
     } else {

src/main/kotlin/Decorator/littlekai/base/IngredientDecorator.kt

@@ -1,7 +1,3 @@
 package Decorator.littlekai.base
 
-abstract class IngredientDecorator (private val noodles: Noodles) : Noodles by noodles {
-  protected abstract val COST : Double
-
-  override fun calculateCost(): Double = noodles.calculateCost() + this.COST
-}
+abstract class IngredientDecorator (private val noodles: Noodles): Noodles by noodles

src/main/kotlin/Decorator/littlekai/base/Noodles.kt

@@ -1,5 +1,6 @@
 package Decorator.littlekai.base
 
 interface Noodles {
-  fun calculateCost() : Double
+  fun calculateCost(): Double
+  fun calculateTotalCost(): Double
 }

src/main/kotlin/Decorator/littlekai/base/SauceDecorator.kt

@@ -1,5 +1,5 @@
 package Decorator.littlekai.base
 
-abstract class SauceDecorator(private val noodles: Noodles) : Noodles by noodles {
+abstract class SauceDecorator(private val noodles: Noodles): Noodles by noodles {
   abstract val SPICINESS: Int
 }

src/main/kotlin/Decorator/littlekai/ingredients/Chicken.kt

@@ -4,6 +4,8 @@ import Decorator.littlekai.base.IngredientDecorator
 import Decorator.littlekai.base.Noodles
 
 
-class Chicken(noodles: Noodles) : IngredientDecorator(noodles) {
-  override val COST: Double = 3.50
+class Chicken(noodles: Noodles): IngredientDecorator(noodles) {
+  val COST: Double = 3.50
+
+  override fun calculateTotalCost(): Double = super.calculateTotalCost() + COST
 }

src/main/kotlin/Decorator/littlekai/ingredients/Peanuts.kt

@@ -4,6 +4,8 @@ import Decorator.littlekai.base.IngredientDecorator
 import Decorator.littlekai.base.Noodles
 
 
-class Peanuts(noodles: Noodles) : IngredientDecorator(noodles) {
-  override val COST: Double = 2.50
+class Peanuts(noodles: Noodles): IngredientDecorator(noodles) {
+  val COST: Double = 2.50
+
+  override fun calculateTotalCost(): Double = super.calculateTotalCost() + COST
 }

src/main/kotlin/Decorator/littlekai/ingredients/Pork.kt

@@ -4,6 +4,8 @@ import Decorator.littlekai.base.IngredientDecorator
 import Decorator.littlekai.base.Noodles
 
 
-class Pork(noodles: Noodles) : IngredientDecorator(noodles) {
-  override val COST: Double = 4.00
+class Pork(noodles: Noodles): IngredientDecorator(noodles) {
+  val COST: Double = 4.00
+
+  override fun calculateTotalCost(): Double = super.calculateTotalCost() + COST
 }

src/main/kotlin/Decorator/littlekai/ingredients/Tuna.kt

@@ -4,6 +4,8 @@ import Decorator.littlekai.base.IngredientDecorator
 import Decorator.littlekai.base.Noodles
 
 
-class Tuna(noodles: Noodles) : IngredientDecorator(noodles) {
-  override val COST: Double = 2.75
+class Tuna(noodles: Noodles): IngredientDecorator(noodles) {
+  val COST: Double = 2.75
+
+  override fun calculateTotalCost(): Double = super.calculateTotalCost() + COST
 }

src/main/kotlin/Decorator/littlekai/noodles/EggNoodles.kt

@@ -2,8 +2,9 @@ package Decorator.littlekai.noodles
 
 import Decorator.littlekai.base.Noodles
 
-class EggNoodles : Noodles {
-  private val COST : Double = 3.75
+class EggNoodles(): Noodles {
+  val COST: Double = 3.75
 
-  override fun calculateCost(): Double = this.COST
+  override fun calculateCost(): Double = COST
+  override fun calculateTotalCost(): Double = COST
 }

src/main/kotlin/Decorator/littlekai/noodles/UdonNoodles.kt

@@ -2,8 +2,9 @@ package Decorator.littlekai.noodles
 
 import Decorator.littlekai.base.Noodles
 
-class UdonNoodles : Noodles {
-  private val COST : Double = 4.00
+class UdonNoodles(): Noodles {
+  val COST: Double = 4.00
 
-  override fun calculateCost(): Double = this.COST
+  override fun calculateCost(): Double = COST
+  override fun calculateTotalCost(): Double = COST
 }

src/main/kotlin/Decorator/littlekai/noodles/WheatNoodles.kt

@@ -2,8 +2,9 @@ package Decorator.littlekai.noodles
 
 import Decorator.littlekai.base.Noodles
 
-class WheatNoodles : Noodles {
-  private val COST : Double = 3.50
+class WheatNoodles(): Noodles {
+  val COST: Double = 3.50
 
-  override fun calculateCost(): Double = this.COST
+  override fun calculateCost(): Double = COST
+  override fun calculateTotalCost(): Double = COST
 }

src/main/kotlin/Decorator/littlekai/sauces/BittersweetSauce.kt

@@ -3,7 +3,7 @@ package Decorator.littlekai.sauces
 import Decorator.littlekai.base.Noodles
 import Decorator.littlekai.base.SauceDecorator
 
-class BittersweetSauce(noodles: Noodles) : SauceDecorator(noodles) {
+class BittersweetSauce(noodles: Noodles): SauceDecorator(noodles) {
   override val SPICINESS: Int = 1
 }
 

src/main/kotlin/Decorator/littlekai/sauces/RedPepperSauce.kt

@@ -4,6 +4,6 @@ import Decorator.littlekai.base.Noodles
 import Decorator.littlekai.base.SauceDecorator
 
 
-class RedPepperSauce(noodles: Noodles) : SauceDecorator(noodles) {
+class RedPepperSauce(noodles: Noodles): SauceDecorator(noodles) {
   override val SPICINESS: Int = 4
 }

src/main/kotlin/Decorator/littlekai/sauces/SateSauce.kt

@@ -3,6 +3,6 @@ package Decorator.littlekai.sauces
 import Decorator.littlekai.base.Noodles
 import Decorator.littlekai.base.SauceDecorator
 
-class SateSauce(noodles: Noodles) : SauceDecorator(noodles) {
+class SateSauce(noodles: Noodles): SauceDecorator(noodles) {
   override val SPICINESS: Int = 2
 }

src/main/kotlin/Decorator/littlekai/sauces/TeriyakiSauce.kt

@@ -4,6 +4,6 @@ import Decorator.littlekai.base.Noodles
 import Decorator.littlekai.base.SauceDecorator
 
 
-class TeriyakiSauce(noodles: Noodles) : SauceDecorator(noodles) {
+class TeriyakiSauce(noodles: Noodles): SauceDecorator(noodles) {
   override val SPICINESS: Int = 0
 }

src/test/kotlin/Decorator/littlekai/base/IngredientDecoratorTest.kt

@@ -1,31 +1,35 @@
 package Decorator.littlekai.base
 
+import Decorator.littlekai.ingredients.Chicken
+import Decorator.littlekai.ingredients.Peanuts
 import Decorator.littlekai.ingredients.Pork
 import Decorator.littlekai.ingredients.Tuna
 import Decorator.littlekai.noodles.EggNoodles
-import Decorator.littlekai.noodles.UdonNoodles
-import Decorator.littlekai.noodles.WheatNoodles
-import org.hamcrest.CoreMatchers.`is`
-import org.junit.Assert.assertThat
+import Decorator.littlekai.sauces.BittersweetSauce
 import org.junit.Assert.assertTrue
 import org.junit.Test
 
 class IngredientDecoratorTest {
 
   @Test
-  fun `check if decorated element is still Noodles`() =
-    assertTrue(Pork(UdonNoodles()) is Noodles) //:+1:
+  fun `has the same interface`() =
+    assertTrue(BittersweetSauce(Chicken(EggNoodles())) is Noodles)
 
   @Test
-  fun `Ingredient Decorator should return ingredient cost plus base noodle cost`() =
-    assertThat(Pork(UdonNoodles()).calculateCost(), `is`(8.00))
+  fun `does not modify behavior`() =
+    assertTrue(EggNoodles().calculateCost() == BittersweetSauce(Chicken(EggNoodles())).calculateCost())
 
   @Test
-  fun `check decorated Noodles is of type IngredientDecorator`() =
-    assertTrue(Tuna(UdonNoodles()) is IngredientDecorator)
+  fun `adds behavior`() =
+    assertTrue(Chicken(EggNoodles()).calculateTotalCost() == EggNoodles().calculateCost() + Chicken(EggNoodles()).COST)
 
   @Test
-  fun `price of ingredient is calculated correctly`() =
-    assertThat(Tuna(Pork(UdonNoodles())).calculateCost(), `is`(10.75))
-
+  fun `is stackable`() =
+    assertTrue(
+      Tuna(Pork(Peanuts(Chicken(EggNoodles())))).calculateTotalCost() ==
+        EggNoodles().COST +
+        Chicken(EggNoodles()).COST +
+        Peanuts(EggNoodles()).COST +
+        Pork(EggNoodles()).COST +
+        Tuna(EggNoodles()).COST)
 }