From 17148ca5e91a79f9cce9177f098c887751091da0 Mon Sep 17 00:00:00 2001
From: Tomasz Lelek <tomasz.lelek@allegrogroup.com>
Date: Mon, 2 Jan 2017 16:22:27 +0100
Subject: [PATCH] BAEL-382 Add extension function that works on list

---
 kotlin/src/main/kotlin/com/baeldung/Item.kt    |  2 +-
 .../main/kotlin/com/baeldung/ListExtension.kt  | 15 +++++++++++++++
 .../kotlin/com/baeldung/ListExtensionTest.kt   | 18 ++++++++++++++++++
 3 files changed, 34 insertions(+), 1 deletion(-)
 create mode 100644 kotlin/src/main/kotlin/com/baeldung/ListExtension.kt
 create mode 100644 kotlin/src/test/kotlin/com/baeldung/ListExtensionTest.kt

diff --git a/kotlin/src/main/kotlin/com/baeldung/Item.kt b/kotlin/src/main/kotlin/com/baeldung/Item.kt
index c0b6dd7631..642b7d6274 100644
--- a/kotlin/src/main/kotlin/com/baeldung/Item.kt
+++ b/kotlin/src/main/kotlin/com/baeldung/Item.kt
@@ -1,4 +1,4 @@
 package com.baeldung
 
 
-data class Item(val id: String, val name: String)
\ No newline at end of file
+data class Item(val id: String, val name: String = "unknown_name")
\ No newline at end of file
diff --git a/kotlin/src/main/kotlin/com/baeldung/ListExtension.kt b/kotlin/src/main/kotlin/com/baeldung/ListExtension.kt
new file mode 100644
index 0000000000..79d2daa1dc
--- /dev/null
+++ b/kotlin/src/main/kotlin/com/baeldung/ListExtension.kt
@@ -0,0 +1,15 @@
+package com.baeldung
+
+import java.util.concurrent.ThreadLocalRandom
+
+
+class ListExtension {
+    fun <T> List<T>.random(): T? {
+        if (this.isEmpty()) return null
+        return get(ThreadLocalRandom.current().nextInt(count()))
+    }
+
+    fun <T> getRandomElementOfList(list: List<T>): T? {
+        return list.random()
+    }
+}
\ No newline at end of file
diff --git a/kotlin/src/test/kotlin/com/baeldung/ListExtensionTest.kt b/kotlin/src/test/kotlin/com/baeldung/ListExtensionTest.kt
new file mode 100644
index 0000000000..42453f2057
--- /dev/null
+++ b/kotlin/src/test/kotlin/com/baeldung/ListExtensionTest.kt
@@ -0,0 +1,18 @@
+package com.baeldung
+
+import org.junit.Test
+import kotlin.test.assertTrue
+
+class ListExtensionTest {
+    @Test
+    fun givenList_whenExecuteExtensionFunctionOnList_shouldReturnRandomElementOfList(){
+        //given
+        val elements = listOf("a", "b", "c")
+
+        //when
+        val result = ListExtension().getRandomElementOfList(elements)
+
+        //then
+        assertTrue(elements.contains(result))
+    }
+}
\ No newline at end of file