Verify index expectations for reduceIndexed/reduceRightIndexed

libraries/stdlib/test/collections/CollectionTest.kt

@@ -223,6 +223,15 @@ class CollectionTest {
             list.reduceIndexed { index, a, b -> if (index == 3) a else a + b }
         }
 
+        expect(5) {
+            listOf(2, 3).reduceIndexed { index, acc: Number, e ->
+                assertEquals(1, index)
+                assertEquals(2, acc)
+                assertEquals(3, e)
+                acc.toInt() + e
+            }
+        }
+
         assertTrue(assertFails {
             arrayListOf<Int>().reduceIndexed { index, a, b -> a + b }
         } is UnsupportedOperationException)
@@ -234,6 +243,15 @@ class CollectionTest {
             list.reduceRightIndexed { index, a, b -> if (index == 0) b else a + b }
         }
 
+        expect(1) {
+            listOf(2, 3).reduceRightIndexed { index, e, acc: Number ->
+                assertEquals(0, index)
+                assertEquals(3, acc)
+                assertEquals(2, e)
+                acc.toInt() - e
+            }
+        }
+
         assertTrue(assertFails {
             arrayListOf<Int>().reduceRightIndexed { index, a, b -> a + b }
         } is UnsupportedOperationException)

libraries/stdlib/test/text/StringTest.kt

@@ -863,6 +863,15 @@ class StringTest {
         // get the 3rd character
         assertEquals('c', arg1("bacfd").reduceIndexed { index, v, c -> if (index == 2) c else v })
 
+        expect('c') {
+            "ab".reduceIndexed { index, acc, e ->
+                assertEquals(1, index)
+                assertEquals('a', acc)
+                assertEquals('b', e)
+                e + (e - acc)
+            }
+        }
+
         assertTrue(assertFails {
             arg1("").reduceIndexed { index, a, b -> '\n' }
         } is UnsupportedOperationException)
@@ -872,6 +881,15 @@ class StringTest {
         // get the 3rd character
         assertEquals('c', arg1("bacfd").reduceRightIndexed { index, c, v -> if (index == 2) c else v })
 
+        expect('c') {
+            "ab".reduceRightIndexed { index, e, acc ->
+                assertEquals(0, index)
+                assertEquals('b', acc)
+                assertEquals('a', e)
+                acc + (acc - e)
+            }
+        }
+
         assertTrue(assertFails {
             arg1("").reduceRightIndexed { index, a, b -> '\n' }
         } is UnsupportedOperationException)