(write-string string s)
(assert (= (file-position s) (+ position string-length))))))
\f
-;;;; success
\ No newline at end of file
+
+;;; See sbcl-devel "Subject: Bug in FILE-POSITION on UTF-8-encoded files"
+;;; by Lutz Euler on 2006-03-05 for more details.
+(with-test (:name (:file-position :utf-8)
+ :fails-on :sbcl)
+ (let ((path "external-format-test.txt"))
+ (with-open-file (s path
+ :direction :output
+ :if-exists :supersede
+ :element-type '(unsigned-byte 8))
+ ;; Write #\*, encoded in UTF-8, to the file.
+ (write-byte 42 s)
+ ;; Append #\adiaeresis, encoded in UTF-8, to the file.
+ (write-sequence '(195 164) s))
+ (with-open-file (s path :external-format :utf-8)
+ (read-char s)
+ (let ((pos (file-position s))
+ (char (read-char s)))
+ (format t "read character with code ~a successfully from file position ~a~%"
+ (char-code char) pos)
+ (file-position s pos)
+ (format t "set file position back to ~a, trying to read-char again~%" pos)
+ (let ((new-char (read-char s)))
+ (assert (char= char new-char)))))
+ (values)))
+
+;;;; success