tp8 step 2

tp8/src/main/kotlin/fmt/kotlin/fundamentals/Cellar.kt

@@ -0,0 +1,17 @@
+package fmt.kotlin.fundamentals
+
+data class Vineyard(
+    val cellars: List<Cellar>
+) {
+
+    fun countBottles() = emptyMap<String, Int>()
+}
+
+data class Cellar(
+    val bottles: List<Bottle>
+)
+
+data class Bottle(
+    val name: String,
+    val year: Int
+)

tp8/src/main/kotlin/fmt/kotlin/fundamentals/MapExt.kt

@@ -0,0 +1,21 @@
+package fmt.kotlin.fundamentals
+
+/**
+ * Merge with [map] using [operation] to compute the new value.
+ *
+ * If one map have no entry for a key, operation is not called and the existing value is used.
+ *
+ * @param K the type of keys in the maps
+ * @param V the type of values in the maps
+ * @param map       the map to merge with
+ * @param operation an operation to call on entry with a value in both map to compute the new value
+ * @return a new map with keys of both maps and values computed with [operation]
+ */
+fun <K, V> Map<K, V>.merge(map: Map<K, V>, operation: (V, V) -> V): Map<K, V> =
+    (keys + map.keys).associateWith { key ->
+        if (this[key] != null && map[key] != null) {
+            operation(this[key]!!, map[key]!!)
+        } else {
+            this[key] ?: map[key]!!
+        }
+    }

tp8/src/test/kotlin/fmt/kotlin/fundamentals/VineyardTest.kt

@@ -0,0 +1,62 @@
+package fmt.kotlin.fundamentals
+
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.Test
+import strikt.api.expectThat
+import strikt.assertions.isEqualTo
+
+class VineyardTest {
+
+    val vineyard = Vineyard(
+        listOf(
+            Cellar(
+                listOf(
+                    Bottle("Coucheroy", 2005),
+                    Bottle("Coucheroy", 2005),
+                    Bottle("Coucheroy", 2015),
+                    Bottle("Coucheroy", 2015),
+                    Bottle("Pedesclaux", 2009),
+                    Bottle("Pedesclaux", 2009),
+                    Bottle("Pedesclaux", 2009),
+                )
+            ),
+            Cellar(
+                listOf(
+                    Bottle("Coucheroy", 2015),
+                    Bottle("Coucheroy", 2015),
+                    Bottle("Coucheroy", 2015),
+                    Bottle("Pedesclaux", 2009),
+                    Bottle("Pedesclaux", 2009),
+                    Bottle("Talbot", 2009),
+                    Bottle("Talbot", 2015),
+                    Bottle("Pedesclaux", 2009),
+                )
+            ),
+            Cellar(
+                listOf(
+                    Bottle("Talbot", 2005),
+                    Bottle("Talbot", 2005),
+                    Bottle("Talbot", 2005),
+                    Bottle("Talbot", 2005),
+                    Bottle("Pedesclaux", 2009),
+                    Bottle("Pedesclaux", 2009),
+                    Bottle("Pedesclaux", 2009),
+                )
+            )
+        )
+    )
+
+
+    @Test
+    fun `should count bottles in all cellars`() {
+        val count = vineyard.countBottles()
+
+        expectThat(count).isEqualTo(
+            mapOf(
+                "Coucheroy" to 7,
+                "Pedesclaux" to 9,
+                "Talbot" to 6
+            )
+        )
+    }
+}