Deprecate withIndicies(), introduce optimized and fixed withIndex and forEachIndexed()

libraries/stdlib/test/collections/IterableTests.kt

@@ -163,6 +163,20 @@ abstract class IterableTests<T : Iterable<String>>(val data: T, val empty: T) {
         assertEquals(arrayListOf(3, 3), lengths)
     }
 
+    Test
+    fun mapIndexed() {
+        val shortened = data.mapIndexed { (index, value)-> value.substring(0..index) }
+        assertEquals(2, shortened.size())
+        assertEquals(arrayListOf("f", "ba"), shortened)
+    }
+
+    Test
+    fun withIndex() {
+        val indexed = data.withIndex().map { it.value.substring(0..it.index) }
+        assertEquals(2, indexed.size())
+        assertEquals(arrayListOf("f", "ba"), indexed)
+    }
+
     Test
     fun max() {
         expect("foo") { data.max() }