From 932f28c69b8573ad85fde2e0fa00cb3a46d93c2e Mon Sep 17 00:00:00 2001
From: Oli Gillespie <ogillespie@openjdk.org>
Date: Fri, 20 Feb 2026 16:50:00 +0000
Subject: [PATCH] 8376698: Add Spliterator tests for TreeMap sub-maps

Reviewed-by: liach, rriggs
---
 .../share/classes/java/util/TreeMap.java      |  6 +++-
 ...SpliteratorTraversingAndSplittingTest.java | 28 +++++++++++++++++--
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/src/java.base/share/classes/java/util/TreeMap.java b/src/java.base/share/classes/java/util/TreeMap.java
index f8eea8c8d8f..8b6e9dc0bd6 100644
--- a/src/java.base/share/classes/java/util/TreeMap.java
+++ b/src/java.base/share/classes/java/util/TreeMap.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2026, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -2138,10 +2138,12 @@ public class TreeMap<K,V>
                 return null;
             }
             public void forEachRemaining(Consumer<? super K> action) {
+                Objects.requireNonNull(action);
                 while (hasNext())
                     action.accept(next());
             }
             public boolean tryAdvance(Consumer<? super K> action) {
+                Objects.requireNonNull(action);
                 if (hasNext()) {
                     action.accept(next());
                     return true;
@@ -2176,10 +2178,12 @@ public class TreeMap<K,V>
                 return null;
             }
             public void forEachRemaining(Consumer<? super K> action) {
+                Objects.requireNonNull(action);
                 while (hasNext())
                     action.accept(next());
             }
             public boolean tryAdvance(Consumer<? super K> action) {
+                Objects.requireNonNull(action);
                 if (hasNext()) {
                     action.accept(next());
                     return true;
diff --git a/test/jdk/java/util/Spliterator/SpliteratorTraversingAndSplittingTest.java b/test/jdk/java/util/Spliterator/SpliteratorTraversingAndSplittingTest.java
index ece63bfe813..c8f882b599d 100644
--- a/test/jdk/java/util/Spliterator/SpliteratorTraversingAndSplittingTest.java
+++ b/test/jdk/java/util/Spliterator/SpliteratorTraversingAndSplittingTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2013, 2026, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -126,12 +126,19 @@ public class SpliteratorTraversingAndSplittingTest extends SpliteratorTestHelper
 
         List<T> exp;
 
+        List<T> expRev;
+
         Map<T, T> mExp;
 
+        Map<T, T> mExpRev;
+
         SpliteratorDataBuilder(List<Object[]> data, List<T> exp) {
             this.data = data;
             this.exp = exp;
+            this.expRev = new ArrayList<>(exp);
+            Collections.reverse(this.expRev);
             this.mExp = createMap(exp);
+            this.mExpRev = createMap(expRev);
         }
 
         Map<T, T> createMap(List<T> l) {
@@ -166,12 +173,23 @@ public class SpliteratorTraversingAndSplittingTest extends SpliteratorTestHelper
             addMap(m, description);
         }
 
+        void addDescendingMap(Function<Map<T, T>, ? extends Map<T, T>> m) {
+            String description = "new " + m.apply(Collections.<T, T>emptyMap()).getClass().getName();
+            addDescendingMap(m, description);
+        }
+
         void addMap(Function<Map<T, T>, ? extends Map<T, T>> m, String description) {
             add(description + ".keySet().spliterator()", () -> m.apply(mExp).keySet().spliterator());
             add(description + ".values().spliterator()", () -> m.apply(mExp).values().spliterator());
             add(description + ".entrySet().spliterator()", mExp.entrySet(), () -> m.apply(mExp).entrySet().spliterator());
         }
 
+        void addDescendingMap(Function<Map<T, T>, ? extends Map<T, T>> m, String description) {
+            add(description + ".keySet().spliterator()", expRev, () -> m.apply(mExp).keySet().spliterator());
+            add(description + ".values().spliterator()", expRev, () -> m.apply(mExp).values().spliterator());
+            add(description + ".entrySet().spliterator()", mExpRev.entrySet(), () -> m.apply(mExp).entrySet().spliterator());
+        }
+
         StringBuilder joiner(String description) {
             return new StringBuilder(description).
                     append(" {").
@@ -639,8 +657,14 @@ public class SpliteratorTraversingAndSplittingTest extends SpliteratorTestHelper
                 return cm;
             }, "new java.util.WeakHashMap(1, size + 1)");
 
-            // @@@  Descending maps etc
             db.addMap(TreeMap::new);
+            db.addMap(m -> new TreeMap<>(m).tailMap(Integer.MIN_VALUE));
+            db.addMap(m -> new TreeMap<>(m).headMap(Integer.MAX_VALUE));
+            db.addMap(m -> new TreeMap<>(m).subMap(Integer.MIN_VALUE, Integer.MAX_VALUE));
+            db.addDescendingMap(m -> new TreeMap<>(m).descendingMap());
+            db.addDescendingMap(m -> new TreeMap<>(m).descendingMap().tailMap(Integer.MAX_VALUE));
+            db.addDescendingMap(m -> new TreeMap<>(m).descendingMap().headMap(Integer.MIN_VALUE));
+            db.addDescendingMap(m -> new TreeMap<>(m).descendingMap().subMap(Integer.MAX_VALUE, Integer.MIN_VALUE));
 
             db.addMap(ConcurrentHashMap::new);