Fix #7855: testlib: add tests for ConcurrentMap to make sure its derived Sets are concurrent

guava-testlib/src/com/google/common/collect/testing/ConcurrentMapTestSuiteBuilder.java

@@ -44,7 +44,8 @@
           ConcurrentMapPutIfAbsentTester.class,
           ConcurrentMapRemoveTester.class,
           ConcurrentMapReplaceTester.class,
-          ConcurrentMapReplaceEntryTester.class);
+          ConcurrentMapReplaceEntryTester.class,
+          ConcurrentMapSpliteratorTester.class);
 
   @SuppressWarnings("rawtypes") // class literals
   @Override

guava-testlib/src/com/google/common/collect/testing/testers/ConcurrentMapSpliteratorTester.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2026 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.common.collect.testing.testers;
+
+import com.google.common.annotations.GwtIncompatible;
+import com.google.common.collect.testing.AbstractMapTester;
+import java.lang.reflect.Method;
+import java.util.List;
+import java.util.Spliterator;
+import java.util.stream.Stream;
+
+@GwtIncompatible
+public class ConcurrentMapSpliteratorTester<K, V> extends AbstractMapTester<K, V> {
+
+  public void testKeySetSpliterator() {
+    Spliterator<K> spliterator = getMap().keySet().spliterator();
+    assertTrue(
+        "keySet spliterator should be CONCURRENT",
+        spliterator.hasCharacteristics(Spliterator.CONCURRENT));
+    assertFalse(
+        "keySet spliterator should not be SIZED",
+        spliterator.hasCharacteristics(Spliterator.SIZED));
+    testStreamToList(getMap().keySet().stream());
+  }
+
+  public void testValuesSpliterator() {
+    Spliterator<V> spliterator = getMap().values().spliterator();
+    assertTrue(
+        "values spliterator should be CONCURRENT",
+        spliterator.hasCharacteristics(Spliterator.CONCURRENT));
+    assertFalse(
+        "values spliterator should not be SIZED",
+        spliterator.hasCharacteristics(Spliterator.SIZED));
+    testStreamToList(getMap().values().stream());
+  }
+
+  public void testEntrySetSpliterator() {
+    Spliterator<java.util.Map.Entry<K, V>> spliterator = getMap().entrySet().spliterator();
+    assertTrue(
+        "entrySet spliterator should be CONCURRENT",
+        spliterator.hasCharacteristics(Spliterator.CONCURRENT));
+    assertFalse(
+        "entrySet spliterator should not be SIZED",
+        spliterator.hasCharacteristics(Spliterator.SIZED));
+    testStreamToList(getMap().entrySet().stream());
+  }
+
+  private void testStreamToList(Stream<?> stream) {
+    try {
+      Method toList = Stream.class.getMethod("toList");
+      List<?> list = (List<?>) toList.invoke(stream);
+      assertEquals(getNumElements(), list.size());
+    } catch (NoSuchMethodException e) {
+      // Stream.toList() not available, just check toArray
+      assertEquals(getNumElements(), stream.toArray().length);
+    } catch (Exception e) {
+      fail("Stream.toList() threw exception: " + e.getCause());
+    }
+  }
+}