In-place reversing.

#KT-9034

libraries/stdlib/test/collections/ArraysTest.kt

@@ -546,6 +546,17 @@ class ArraysTest {
         } is UnsupportedOperationException)
     }
 
+    @test fun reverseInPlace() {
+        assertArrayNotSameButEquals(intArrayOf(3, 2, 1), intArrayOf(1, 2, 3).apply { reverse() })
+        assertArrayNotSameButEquals(byteArrayOf(3, 2, 1), byteArrayOf(1, 2, 3).apply { reverse() })
+        assertArrayNotSameButEquals(shortArrayOf(3, 2, 1), shortArrayOf(1, 2, 3).apply { reverse() })
+        assertArrayNotSameButEquals(longArrayOf(3, 2, 1), longArrayOf(1, 2, 3).apply { reverse() })
+        assertArrayNotSameButEquals(floatArrayOf(3F, 2F, 1F), floatArrayOf(1F, 2F, 3F).apply { reverse() })
+        assertArrayNotSameButEquals(doubleArrayOf(3.0, 2.0, 1.0), doubleArrayOf(1.0, 2.0, 3.0).apply { reverse() })
+        assertArrayNotSameButEquals(charArrayOf('3', '2', '1'), charArrayOf('1', '2', '3').apply { reverse() })
+        assertArrayNotSameButEquals(booleanArrayOf(false, false, true), booleanArrayOf(true, false, false).apply { reverse() })
+    }
+
     @test fun reversed() {
         expect(listOf(3, 2, 1)) { intArrayOf(1, 2, 3).reversed() }
         expect(listOf<Byte>(3, 2, 1)) { byteArrayOf(1, 2, 3).reversed() }

libraries/stdlib/test/collections/CollectionTest.kt

@@ -310,22 +310,29 @@ class CollectionTest {
         }
     }
 
-    @test fun reverse() {
+    @test fun reverseInPlace() {
+        val data = arrayListOf<String>()
+        data.reverse()
+        assertTrue(data.isEmpty())
+
+        data.add("foo")
+        data.reverse()
+        assertEquals(listOf("foo"), data)
+
+        data.add("bar")
+        data.reverse()
+        assertEquals(listOf("bar", "foo"), data)
+
+        data.add("zoo")
+        data.reverse()
+        assertEquals(listOf("zoo", "foo", "bar"), data)
+    }
+
+    @test fun reversed() {
         val data = listOf("foo", "bar")
         val rev = data.reversed()
         assertEquals(listOf("bar", "foo"), rev)
-    }
-
-    @test fun reverseFunctionShouldReturnReversedCopyForList() {
-        val list: List<Int> = listOf(2, 3, 1)
-        expect(listOf(1, 3, 2)) { list.reversed() }
-        expect(listOf(2, 3, 1)) { list }
-    }
-
-    @test fun reverseFunctionShouldReturnReversedCopyForIterable() {
-        val iterable: Iterable<Int> = listOf(2, 3, 1)
-        expect(listOf(1, 3, 2)) { iterable.reversed() }
-        expect(listOf(2, 3, 1)) { iterable }
+        assertNotEquals(data, rev)
     }