Initial implementation of EnumEntries

KT-53152


Merge-request: KT-MR-6656
Merged-by: Vsevolod Tolstopyatov <vsevolod.tolstopyatov@jetbrains.com>

libraries/stdlib/test/enums/EnumEntriesListTest.kt

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2010-2022 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+@file:Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+package test.enums
+
+import kotlin.enums.enumEntries
+import kotlin.test.*
+import test.collections.behaviors.listBehavior
+import test.collections.compare
+
+class EnumEntriesListTest {
+
+    enum class EmptyEnum
+
+    enum class NonEmptyEnum {
+        A, B, C
+    }
+
+    @Test
+    fun testForEmptyEnum() {
+        val list = enumEntries(EmptyEnum::values)
+        assertTrue(list.isEmpty())
+        assertEquals(0, list.size)
+        assertFalse { list is MutableList<*> }
+        assertFailsWith<IndexOutOfBoundsException> { list[0] }
+        assertFailsWith<IndexOutOfBoundsException> { list[-1] }
+    }
+
+    @Test
+    fun testEmptyEnumBehaviour() {
+        val list = enumEntries(EmptyEnum::values)
+        compare(EmptyEnum.values().toList(), list) { listBehavior() }
+    }
+
+    @Test
+    fun testForEnum() {
+        val list = enumEntries(NonEmptyEnum::values)
+        val goldenCopy = NonEmptyEnum.values().toList()
+        assertEquals(goldenCopy, list)
+        assertFalse { list is MutableList<*> }
+        for ((idx, e) in goldenCopy.withIndex()) {
+            assertEquals(e, list[e.ordinal])
+            assertEquals(idx, list.indexOf(e))
+            assertEquals(e, list[idx])
+        }
+        assertFailsWith<IndexOutOfBoundsException> { list[-1] }
+        assertFailsWith<IndexOutOfBoundsException> { list[goldenCopy.size] }
+    }
+
+    @Test
+    fun testyEnumBehaviour() {
+        val list = enumEntries(NonEmptyEnum::values)
+        compare(NonEmptyEnum.values().toList(), list) { listBehavior() }
+    }
+}