[KTLN-495] Add Sammples (Baeldung#612)

core-kotlin-modules/core-kotlin-arrays/src/test/kotlin/com/baeldung/indexof/IndexOfTests.kt

@@ -0,0 +1,60 @@
+package com.baeldung.indexof
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+
+
+class IndexOfTests {
+
+    @Test
+    fun `Find index using indexOf`() {
+        val numbers = arrayOf(1, 2, 3, 4, 5)
+        val elementToFind = 3
+        val index = numbers.indexOf(elementToFind)
+
+        assertEquals(2, index)
+    }
+
+    @Test
+    fun `Find index of first`() {
+        val numbers = arrayOf(1, 2, 3, 4, 3, 5)
+        val elementToFind = 3
+        val index = numbers.indexOfFirst { it == elementToFind }
+
+        assertEquals(2, index)
+    }
+
+    @Test
+    fun `Find last index of element`() {
+        val numbers = arrayOf(1, 2, 3, 4, 3, 5)
+        val elementToFind = 3
+        val lastIndex = numbers.lastIndexOf(elementToFind)
+
+        assertEquals(4, lastIndex)
+    }
+
+    @Test
+    fun `Find index of last`() {
+        val numbers = arrayOf(1, 2, 3, 4, 3, 5)
+        val elementToFind = 3
+        val index = numbers.indexOfLast { it == elementToFind }
+
+        assertEquals(4, index)
+    }
+
+    @Test
+    fun `Find indices using loop`() {
+        val numbers = arrayOf(1, 2, 3, 4, 3, 5)
+        val elementToFind = 3
+        val indices = mutableListOf<Int>()
+
+        for (i in numbers.indices) {
+            if (numbers[i] == elementToFind) {
+                indices.add(i)
+            }
+        }
+
+        assertEquals(listOf(2, 4), indices)
+    }
+
+}