KT-57607 Add test for MutableList.addAll at index

Also improve other operations test coverage

libraries/stdlib/test/collections/MutableCollectionsTest.kt

@@ -6,6 +6,7 @@
 package test.collections
 
 import kotlin.random.Random
+import kotlin.random.nextInt
 import kotlin.test.*
 
 
@@ -39,24 +40,57 @@ class MutableCollectionTest {
         }
     }
 
+    private fun <T> forAllStandardMutableLists(data: List<T>, block: (MutableList<T>) -> Unit) {
+        block(data.toMutableList())
+        block(ArrayDeque(data))
+        buildList {
+            addAll(data)
+            block(this)
+        }
+    }
+
+    @Test fun addAllAtIndex() {
+        val original = List(15000) { Random.nextInt() }
+        for (insertSize in listOf(0, 1, 10, 1000, 20000)) {
+            val insertion = List(insertSize) { Random.nextInt() }
+            for (index in listOf(0, original.size) + List(10) { Random.nextInt(original.indices) }) {
+                forAllStandardMutableLists(original) { mutable ->
+                    mutable.addAll(index, insertion)
+
+                    assertEquals(original.size + insertSize, mutable.size)
+                    val tailIndex = index + insertSize
+                    for (i in 0..<index) {
+                        assertEquals(original[i], mutable[i])
+                    }
+                    for (i in index..<tailIndex) {
+                        assertEquals(insertion[i - index], mutable[i])
+                    }
+                    for (i in tailIndex..<mutable.size) {
+                        assertEquals(original[i - insertSize], mutable[i])
+                    }
+                }
+            }
+        }
+    }
+
     @Test fun removeFirst() {
-        val list = mutableListOf("first", "second")
+        forAllStandardMutableLists(listOf("first", "second")) { list ->
+            assertEquals("first", list.removeFirst())
+            assertEquals("second", list.removeFirstOrNull())
 
-        assertEquals("first", list.removeFirst())
-        assertEquals("second", list.removeFirstOrNull())
-
-        assertNull(list.removeFirstOrNull())
-        assertFailsWith<NoSuchElementException> { list.removeFirst() }
+            assertNull(list.removeFirstOrNull())
+            assertFailsWith<NoSuchElementException> { list.removeFirst() }
+        }
     }
 
     @Test fun removeLast() {
-        val list = mutableListOf("first", "second")
+        forAllStandardMutableLists(listOf("first", "second")) { list ->
+            assertEquals("second", list.removeLast())
+            assertEquals("first", list.removeLastOrNull())
 
-        assertEquals("second", list.removeLast())
-        assertEquals("first", list.removeLastOrNull())
-
-        assertNull(list.removeLastOrNull())
-        assertFailsWith<NoSuchElementException> { list.removeLast() }
+            assertNull(list.removeLastOrNull())
+            assertFailsWith<NoSuchElementException> { list.removeLast() }
+        }
     }
 
     @Test fun removeAll() {
@@ -121,9 +155,10 @@ class MutableCollectionTest {
     }
 
     @Test fun listFill() {
-        val list = MutableList(3) { it }
-        list.fill(42)
-        assertEquals(listOf(42, 42, 42), list)
+        forAllStandardMutableLists(List(3) { it }) { list ->
+            list.fill(42)
+            assertEquals(listOf(42, 42, 42), list)
+        }
     }
 
     @Test fun shuffled() {