Fix test failure on win 11.

lucene/core/src/java/org/apache/lucene/util/Constants.java

@@ -41,6 +41,9 @@ public final class Constants {
   /** True iff running on Windows. */
   public static final boolean WINDOWS = OS_NAME.startsWith("Windows");
 
+  /** True iff running on Windows and the version is on or after Windows 11. */
+  public static final boolean ON_OR_AFTER_WINDOWS_11 = onOrAfterWindows(11);
+
   /** True iff running on SunOS. */
   public static final boolean SUN_OS = OS_NAME.startsWith("SunOS");
 
@@ -100,6 +103,24 @@ public final class Constants {
   /** true iff we know FMA has faster throughput than separate mul/add. */
   public static final boolean HAS_FAST_SCALAR_FMA = hasFastScalarFMA();
 
+  private static boolean onOrAfterWindows(float version){
+    if(WINDOWS){
+      String[] s = OS_NAME.split(" ");
+      // False for Windows Server 2022, etc.
+      if(s.length == 2){
+        try{
+          if(Float.parseFloat(s[1]) >= version){
+            return true;
+          }
+        }catch (NumberFormatException e){
+          // False for Windows XP, etc.
+          return false;
+        }
+      }
+    }
+    return false;
+  }
+
   private static boolean hasFastVectorFMA() {
     if (HAS_FMA) {
       String value = getSysProp("lucene.useVectorFMA", "auto");

lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java

@@ -1298,13 +1298,21 @@ public class TestIndexWriter extends LuceneTestCase {
       // NOTE: here we rely on "Windows" behavior, i.e. even though IW wanted to delete _0.cfs
       // since it was merged away, because we have a reader open against this file,
       // it should still be here:
-      assertTrue(Files.exists(indexPath.resolve("_0.cfs")));
+      if(iter == 1 && Constants.ON_OR_AFTER_WINDOWS_11){
+        assertFalse(Files.exists(indexPath.resolve("_0.cfs")));
+      }else{
+        assertTrue(Files.exists(indexPath.resolve("_0.cfs")));
+      }
       // forceMerge created this
       // assertTrue(files.contains("_2.cfs"));
       w.deleteUnusedFiles();
 
       // r still holds this file open
-      assertTrue(Files.exists(indexPath.resolve("_0.cfs")));
+      if(iter == 1 && Constants.ON_OR_AFTER_WINDOWS_11){
+        assertFalse(Files.exists(indexPath.resolve("_0.cfs")));
+      }else{
+        assertTrue(Files.exists(indexPath.resolve("_0.cfs")));
+      }
       // assertTrue(files.contains("_2.cfs"));
 
       r.close();
@@ -1324,6 +1332,7 @@ public class TestIndexWriter extends LuceneTestCase {
     }
   }
 
+
   public void testDeleteUnusedFiles2() throws Exception {
     // Validates that iw.deleteUnusedFiles() also deletes unused index commits
     // in case a deletion policy which holds onto commits is used.