Add unit tests for quality rules except Aged Brie and Backstage Passes

src/test/kotlin/com/gildedrose/QualityTest.kt

@@ -1,9 +1,8 @@
 package com.gildedrose
 
-import com.gildedrose.core.TestUtils
+import com.gildedrose.core.*
 import com.gildedrose.core.TestUtils.generateRandomNumber
 import com.gildedrose.core.TestUtils.pickRandomItem
-import com.gildedrose.core.advanceTimeBy
 import org.assertj.core.api.Java6Assertions.assertThat
 import org.junit.Before
 import org.junit.Test
@@ -18,28 +17,72 @@ class QualityTest {
     }
 
     @Test
-    fun givenKnownItemExcepSulfuras_afterAnyNumberOfDays_shouldHaveQualityGreaterThanOrEqualToZero() {
+    fun givenSulfuras_afterAnyNumberOfDays_shouldHaveQualityEighty() {
+        val days = generateRandomNumber()
+        val item = Item("Sulfuras, Hand of Ragnaros", generateRandomNumber(), 80)
+        val app = GildedRose(arrayOf(item))
+
+        app.advanceTimeBy(days)
+
+        assertThat(item.quality).isEqualTo(80)
+    }
+
+    @Test
+    fun givenKnownItemsExceptSulfuras_afterAnyNumberOfDays_shouldHaveQualityGreaterThanOrEqualToZero() {
+        store = store.excludeSulfuras()
         val days = generateRandomNumber()
-        store = store.filter { it.name != "Sulfuras, Hand of Ragnaros" }
         val app = GildedRose(store.toTypedArray())
 
         app.advanceTimeBy(days)
 
-        store.forEach {item ->
+        store.forEach { item ->
             assertThat(item.quality).isGreaterThanOrEqualTo(0)
         }
     }
 
     @Test
-    fun givenKnownItemExcepSulfuras_afterAnyNumberOfDays_shouldHaveQualityLessThanOrEqualToFifty() {
+    fun givenKnownItemsExceptSulfuras_afterAnyNumberOfDays_shouldHaveQualityLessThanOrEqualToFifty() {
+        store = store.excludeSulfuras()
         val days = generateRandomNumber()
-        store = store.filter { it.name != "Sulfuras, Hand of Ragnaros" }
         val app = GildedRose(store.toTypedArray())
 
         app.advanceTimeBy(days)
 
-        store.forEach {item ->
+        store.forEach { item ->
             assertThat(item.quality).isLessThanOrEqualTo(50)
         }
     }
+
+    @Test
+    fun givenKnownItemWithDegradingQuality_whenSellInIsGreaterThanOrEqualToZero_shouldDegradeQualityByNumberOfDays() {
+        store = store.excludeSulfuras()
+                .excludeBackstagePasses()
+                .excludeAgedBrie()
+        val days = generateRandomNumber().coerceAtLeast(0)
+        val item = pickRandomItem(store)
+        val initialItemQuality = item.quality
+        val app = GildedRose(arrayOf(item))
+
+        app.advanceTimeBy(days)
+
+        val expectedQuality = (initialItemQuality - days).coerceAtLeast(0)
+        assertThat(item.quality).isEqualTo(expectedQuality)
+    }
+
+    @Test
+    fun givenKnownItemWithDegradingQuality_whenSellInIsLessThanZero_shouldDegradeQualityByTwiceTheNumberOfDays() {
+        store = store.excludeSulfuras()
+                .excludeBackstagePasses()
+                .excludeAgedBrie()
+        val sellIn = (-99 until 0).shuffled().last()
+        val days = (0 until 100).shuffled().last()
+        val item = pickRandomItem(store).copy(sellIn = sellIn)
+        val initialItemQuality = item.quality
+        val app = GildedRose(arrayOf(item))
+
+        app.advanceTimeBy(days)
+
+        val expectedQuality = (initialItemQuality - days * 2).coerceAtLeast(0)
+        assertThat(item.quality).isEqualTo(expectedQuality)
+    }
 }

src/test/kotlin/com/gildedrose/SellInTest.kt

@@ -11,11 +11,11 @@ import org.junit.Test
 
 class SellInTest {
 
-    private lateinit var store: Array<Item>
+    private lateinit var store: List<Item>
 
     @Before
     fun setUp() {
-        store = TestUtils.fixture
+        store = TestUtils.fixture.toList()
     }
 
     @Test
@@ -31,14 +31,11 @@ class SellInTest {
     }
 
     @Test
-    fun givenKnownItemExcepSulfuras_afterRandomNumberOfDays_shouldDecreaseSellInByNumberOfDays() {
+    fun givenKnownItemExceptSulfuras_afterRandomNumberOfDays_shouldDecreaseSellInByNumberOfDays() {
+        store = store.filter { it.name != "Sulfuras, Hand of Ragnaros" }
         val days = generateRandomNumber()
         val initialSellIn = generateRandomNumber()
-        var item = pickRandomItem(store).copy(sellIn = initialSellIn)
-
-        while (item.name == "Sulfuras, Hand of Ragnaros") {
-            item = pickRandomItem(store).copy(sellIn = initialSellIn)
-        }
+        val item = pickRandomItem(store).copy(sellIn = initialSellIn)
 
         val app = GildedRose(arrayOf(item))
 

src/test/kotlin/com/gildedrose/core/TestExtensions.kt

@@ -0,0 +1,7 @@
+package com.gildedrose.core
+
+import com.gildedrose.Item
+
+fun List<Item>.excludeSulfuras() = this.filter { it.name != "Sulfuras, Hand of Ragnaros" }
+fun List<Item>.excludeBackstagePasses() = this.filter { it.name != "Backstage passes to a TAFKAL80ETC concert" }
+fun List<Item>.excludeAgedBrie() = this.filter { it.name != "Aged Brie" }

src/test/kotlin/com/gildedrose/core/TestUtils.kt

@@ -21,5 +21,5 @@ object TestUtils {
 
     fun generateRandomNumber() = (0 until 9999).shuffled().last()
 
-    fun pickRandomItem(items: Array<Item>) = items[generateRandomNumber().coerceIn(items.indices)]
+    fun pickRandomItem(items: List<Item>) = items[items.indices.shuffled().last()]
 }

texttest/specs.txt

@@ -1,13 +1,12 @@
 SPECS
     LOGIC
-        - sellIn decreases every day
+        # - sellIn decreases every day
         - Item.quality
-            - is >= 0 && <= 50
-            - decreses until sellIn is <= 0
-            - when sellIn == 0 quality degrades twice as fast
+            # - is >= 0 && <= 50
+            # - decrements with number of days until sellIn is 0 then with the double of it
         - Sulfuras
-            sellIn = 0 // doesnt change
-            quality is 80 and does not decrease
+            # sellIn = 0 // doesnt change
+            # quality is 80 and does not decrease
         - AgedBrie increases in quality
         - BackstagePasses
             increases in quality like AgedBrie