Solve 'Help the bookseller !' kata

pom.xml

@@ -69,7 +69,7 @@
     <dependencies>
         <dependency>
             <groupId>org.jetbrains.kotlin</groupId>
-            <artifactId>kotlin-stdlib-jdk8</artifactId>
+            <artifactId>kotlin-stdlib</artifactId>
             <version>${kotlin.language.version}</version>
         </dependency>
 

src/main/kotlin/helpthebookseller/StockList.kt

@@ -0,0 +1,43 @@
+package solution
+
+/**
+ * https://www.codewars.com/kata/54dc6f5a224c26032800005c/train/kotlin
+ */
+object StockList {
+    fun stockSummary(lstOfArt: Array<String>, lstOfCat: Array<String>): String {
+        if (lstOfArt.isEmpty()) {
+            return ""
+        }
+
+        val stock = lstOfArt
+            .map(::readOne)
+            .groupBy { it.category }
+            .map { (key, value) ->
+                StockItem(key, value.sumOf { it.quantity })
+            }
+            .associateBy { it.category }
+
+        return lstOfCat
+            .map {
+                stock[it] ?: StockItem(it, 0)
+            }
+            .joinToString(" - ") {
+                "(${it.category} : ${it.quantity})"
+            }
+    }
+}
+
+data class StockItem(val category: String, val quantity: Int) {
+}
+
+val stockItemPattern = """([A-Z][A-Z0-9]+) ([0-9]+)""".toRegex()
+
+fun readOne(input: String): StockItem {
+    val match = stockItemPattern.matchEntire(input)
+    val groups = match!!.groups
+
+    val category = groups[1]!!.value
+    val quantity = groups[2]!!.value
+
+    return StockItem(category.take(1), quantity.toInt())
+}

src/test/kotlin/helpthebookseller/StockListTest.kt

@@ -0,0 +1,53 @@
+package solution
+
+import org.junit.Test
+import kotlin.test.assertEquals
+
+class StockListTest {
+
+    private fun testing(lstOfArt: Array<String>, lstOfCat: Array<String>, expect: String) {
+        val actual: String = StockList.stockSummary(lstOfArt, lstOfCat)
+        assertEquals(expect, actual)
+    }
+
+    @Test
+    fun basicTest1() {
+        val b = arrayOf("BBAR 150", "CDXE 515", "BKWR 250", "BTSQ 890", "DRTY 600")
+        val c = arrayOf("A", "B", "C", "D")
+        val res = "(A : 0) - (B : 1290) - (C : 515) - (D : 600)"
+        testing(b, c, res)
+    }
+
+    @Test
+    fun basicTest2() {
+        val b = arrayOf("ABAR 200", "CDXE 500", "BKWR 250", "BTSQ 890", "DRTY 600")
+        val c = arrayOf("A", "B")
+        val res = "(A : 200) - (B : 1140)"
+        testing(b, c, res)
+    }
+
+    @Test
+    fun basicTest3() {
+        val b = arrayOf(
+            "ROXANNE 102",
+            "RHODODE 123",
+            "BKWRKAA 125",
+            "BTSQZFG 239",
+            "DRTYMKH 060",
+            "RHIB 1230",
+            "R0 530",
+            "XILO 32"
+        )
+        val c = arrayOf("U", "V", "R")
+        val res = "(U : 0) - (V : 0) - (R : 1985)"
+        testing(b, c, res)
+    }
+
+    @Test
+    fun emptyTest() {
+        val b = emptyArray<String>()
+        val c = arrayOf("A", "B", "C", "D")
+        val res = ""
+        testing(b, c, res)
+    }
+}