IO-789 Symbolic link file filter accepts all files, not just symbolic links

src/main/java/org/apache/commons/io/filefilter/SymbolicLinkFileFilter.java

@@ -87,25 +87,37 @@ public SymbolicLinkFileFilter(final FileVisitResult onAccept, final FileVisitRes
     }
 
     /**
-     * Checks to see if the file is a file.
+     * Checks to see if the file is a symbolic link.
      *
      * @param file  the File to check
-     * @return true if the file is a file
+     * @return true if the file exists and is a symbolic link to either another file or a directory,
+     *         false otherwise.
      */
     @Override
     public boolean accept(final File file) {
-        return file.isFile();
+        return isSymbolicLink(file.toPath());
     }
 
     /**
-     * Checks to see if the file is a symbolic link.
-     * @param file  the File to check
+     * Checks to see if the file is a file.
      *
-     * @return true if the file is a symbolic link.
+     * @param path the File Path to check
+     * @return true if the file exists and is a symbolic link to either another file or a directory.
      */
     @Override
-    public FileVisitResult accept(final Path file, final BasicFileAttributes attributes) {
-        return toFileVisitResult(Files.isSymbolicLink(file));
+    public FileVisitResult accept(final Path path, final BasicFileAttributes attributes) {
+        return toFileVisitResult(isSymbolicLink(path));
     }
 
+    /**
+     * Package access, so the unit test may override to mock it. To
+     * facilitate unit testing, all calls to test if the file is a symbolic should go
+     * through this method. (See the unit test for why.)
+     *
+     * @param filePath The filePath to test
+     * @return true if the file exists and is a symbolic link to either a file or directory, false otherwise.
+     */
+    boolean isSymbolicLink(Path filePath) {
+        return Files.isSymbolicLink(filePath);
+    }
 }