Fix WindowsFS test failure seen on Policeman Jenkins (#14706)

Author: uschindler

lucene/CHANGES.txt

@@ -142,9 +142,9 @@ Other
 
 * GITHUB#14516: Move sloppySin into SloppyMath from GeoUtils (Ankit Jain)
 
-* GITHUB#14627, GITHUB#11920: Fix mock filesystem WindowsFS to also work on Windows.
-  This is required to make tests pass on Windows 11 which no longer has
-  all limitations of previous Windows versions.  (Uwe Schindler)
+* GITHUB#14627, GITHUB#11920, GITHUB#14706: Fix mock filesystem WindowsFS to also
+  work on Windows. This is required to make tests pass on Windows 11 which no
+  longer has all limitations of previous Windows versions.  (Uwe Schindler)
 
 
 ======================= Lucene 10.2.1 =======================

lucene/test-framework/src/test/org/apache/lucene/tests/mockfile/TestWindowsFS.java

@@ -197,14 +197,16 @@ public void testFileName() {
     if (r.nextBoolean()) {
       // We need at least one char after the special char
       // For example, in case of '/' we interpret `foo/` to just be a file `foo` which is valid
+      // We need at least 2 chars before the special character, because resolving a drive
+      // letter (C:) or a path starting with "/" will not fail on real Windows.
       fileName =
-          RandomStrings.randomAsciiLettersOfLength(r, r.nextInt(10))
+          RandomStrings.randomAsciiLettersOfLength(r, r.nextInt(2, 10))
               + reservedCharacters[r.nextInt(reservedCharacters.length)]
               + RandomStrings.randomAsciiLettersOfLength(r, r.nextInt(1, 10));
     } else {
       fileName = reservedNames[r.nextInt(reservedNames.length)];
     }
-    expectThrows(InvalidPathException.class, () -> dir.resolve(fileName));
+    expectThrows(InvalidPathException.class, fileName, () -> dir.resolve(fileName));
 
     // some other basic tests
     expectThrows(InvalidPathException.class, () -> dir.resolve("foo:bar"));