diff --git a/testsuite/tests/lib-format/Makefile b/testsuite/tests/lib-format/Makefile
new file mode 100644
index 000000000..0248fe1a5
--- /dev/null
+++ b/testsuite/tests/lib-format/Makefile
@@ -0,0 +1,19 @@
+#########################################################################
+#                                                                       #
+#                                 OCaml                                 #
+#                                                                       #
+#                 Xavier Clerc, SED, INRIA Rocquencourt                 #
+#                                                                       #
+#   Copyright 2010 Institut National de Recherche en Informatique et    #
+#   en Automatique.  All rights reserved.  This file is distributed     #
+#   under the terms of the Q Public License version 1.0.                #
+#                                                                       #
+#########################################################################
+
+#MODULES=
+MAIN_MODULE=tformat
+ADD_COMPFLAGS=-I $(BASEDIR)/lib
+ADD_MODULES=testing
+
+include ../../makefiles/Makefile.one
+include ../../makefiles/Makefile.common
diff --git a/testsuite/tests/lib-format/tformat.ml b/testsuite/tests/lib-format/tformat.ml
new file mode 100644
index 000000000..cf2f4fc9e
--- /dev/null
+++ b/testsuite/tests/lib-format/tformat.ml
@@ -0,0 +1,466 @@
+(*************************************************************************)
+(*                                                                       *)
+(*                                OCaml                                  *)
+(*                                                                       *)
+(*         Pierre Weis, projet Pomdapi, INRIA Rocquencourt               *)
+(*                                                                       *)
+(*   Copyright 2011 Institut National de Recherche en Informatique et    *)
+(*   en Automatique.  All rights reserved.  This file is distributed     *)
+(*   under the terms of the Q Public License version 1.0.                *)
+(*                                                                       *)
+(*************************************************************************)
+
+(*
+
+A test file for the Format module.
+
+*)
+
+open Testing;;
+open Format;;
+
+try
+
+  printf "d/i positive\n%!";
+  test (sprintf "%d/%i" 42 43 = "42/43");
+  test (sprintf "%-4d/%-5i" 42 43 = "42  /43   ");
+  test (sprintf "%04d/%05i" 42 43 = "0042/00043");
+  test (sprintf "%+d/%+i" 42 43 = "+42/+43");
+  test (sprintf "% d/% i" 42 43 = " 42/ 43");
+  test (sprintf "%#d/%#i" 42 43 = "42/43");
+  test (sprintf "%4d/%5i" 42 43 = "  42/   43");
+  test (sprintf "%*d/%*i" 4 42 5 43 = "  42/   43");
+  test (sprintf "%-0+#4d/%-0 #5i" 42 43 = "+42 / 43  ");
+
+  printf "\nd/i negative\n%!";
+  test (sprintf "%d/%i" (-42) (-43) = "-42/-43");
+  test (sprintf "%-4d/%-5i" (-42) (-43) = "-42 /-43  ");
+  test (sprintf "%04d/%05i" (-42) (-43) = "-042/-0043");
+  test (sprintf "%+d/%+i" (-42) (-43) = "-42/-43");
+  test (sprintf "% d/% i" (-42) (-43) = "-42/-43");
+  test (sprintf "%#d/%#i" (-42) (-43) = "-42/-43");
+  test (sprintf "%4d/%5i" (-42) (-43) = " -42/  -43");
+  test (sprintf "%*d/%*i" 4 (-42) 5 (-43) = " -42/  -43");
+  test (sprintf "%-0+ #4d/%-0+ #5i" (-42) (-43) = "-42 /-43  ");
+
+  printf "\nu positive\n%!";
+  test (sprintf "%u" 42 = "42");
+  test (sprintf "%-4u" 42 = "42  ");
+  test (sprintf "%04u" 42 = "0042");
+  test (sprintf "%+u" 42 = "42");
+  test (sprintf "% u" 42 = "42");
+  test (sprintf "%#u" 42 = "42");
+  test (sprintf "%4u" 42 = "  42");
+  test (sprintf "%*u" 4 42 = "  42");
+  test (sprintf "%-0+ #6d" 42 = "+42   ");
+
+  printf "\nu negative\n%!";
+  begin match Sys.word_size with
+  | 32 ->
+     test (sprintf "%u" (-1) = "2147483647");
+  | 64 ->
+     test (sprintf "%u" (-1) = "9223372036854775807");
+  | _ -> test false
+  end;
+
+  printf "\nx positive\n%!";
+  test (sprintf "%x" 42 = "2a");
+  test (sprintf "%-4x" 42 = "2a  ");
+  test (sprintf "%04x" 42 = "002a");
+  test (sprintf "%+x" 42 = "2a");
+  test (sprintf "% x" 42 = "2a");
+  test (sprintf "%#x" 42 = "0x2a");
+  test (sprintf "%4x" 42 = "  2a");
+  test (sprintf "%*x" 5 42 = "   2a");
+  test (sprintf "%-0+ #*x" 5 42 = "0x2a ");
+
+  printf "\nx negative\n%!";
+  begin match Sys.word_size with
+  | 32 ->
+     test (sprintf "%x" (-42) = "7fffffd6");
+  | 64 ->
+     test (sprintf "%x" (-42) = "7fffffffffffffd6");
+  | _ -> test false
+  end;
+
+  printf "\nX positive\n%!";
+  test (sprintf "%X" 42 = "2A");
+  test (sprintf "%-4X" 42 = "2A  ");
+  test (sprintf "%04X" 42 = "002A");
+  test (sprintf "%+X" 42 = "2A");
+  test (sprintf "% X" 42 = "2A");
+  test (sprintf "%#X" 42 = "0X2A");
+  test (sprintf "%4X" 42 = "  2A");
+  test (sprintf "%*X" 5 42 = "   2A");
+  test (sprintf "%-0+ #*X" 5 42 = "0X2A ");
+
+  printf "\nx negative\n%!";
+  begin match Sys.word_size with
+  | 32 ->
+     test (sprintf "%X" (-42) = "7FFFFFD6");
+  | 64 ->
+     test (sprintf "%X" (-42) = "7FFFFFFFFFFFFFD6");
+  | _ -> test false
+  end;
+
+  printf "\no positive\n%!";
+  test (sprintf "%o" 42 = "52");
+  test (sprintf "%-4o" 42 = "52  ");
+  test (sprintf "%04o" 42 = "0052");
+  test (sprintf "%+o" 42 = "52");
+  test (sprintf "% o" 42 = "52");
+  test (sprintf "%#o" 42 = "052");
+  test (sprintf "%4o" 42 = "  52");
+  test (sprintf "%*o" 5 42 = "   52");
+  test (sprintf "%-0+ #*o" 5 42 = "052  ");
+
+  printf "\no negative\n%!";
+  begin match Sys.word_size with
+  | 32 ->
+     test (sprintf "%o" (-42) = "17777777726");
+  | 64 ->
+     test (sprintf "%o" (-42) = "777777777777777777726");
+  | _ -> test false
+  end;
+
+  printf "\ns\n%!";
+  test (sprintf "%s" "foo" = "foo");
+  test (sprintf "%-5s" "foo" = "foo  ");
+  test (sprintf "%05s" "foo" = "  foo");
+  test (sprintf "%+s" "foo" = "foo");
+  test (sprintf "% s" "foo" = "foo");
+  test (sprintf "%#s" "foo" = "foo");
+  test (sprintf "%5s" "foo" = "  foo");
+  test (sprintf "%1s" "foo" = "foo");
+  test (sprintf "%*s" 6 "foo" = "   foo");
+  test (sprintf "%*s" 2 "foo" = "foo");
+  test (sprintf "%-0+ #5s" "foo" = "foo  ");
+  test (sprintf "%s@" "foo" = "foo@");
+  test (sprintf "%s@inria.fr" "foo" = "foo@inria.fr");
+  test (sprintf "%s@%s" "foo" "inria.fr" = "foo@inria.fr");
+
+  printf "\nS\n%!";
+  test (sprintf "%S" "fo\"o" = "\"fo\\\"o\"");
+(*  test (sprintf "%-5S" "foo" = "\"foo\"  ");   padding not done *)
+(*  test (sprintf "%05S" "foo" = "  \"foo\"");   padding not done *)
+  test (sprintf "%+S" "foo" = "\"foo\"");
+  test (sprintf "% S" "foo" = "\"foo\"");
+  test (sprintf "%#S" "foo" = "\"foo\"");
+(*  test (sprintf "%5S" "foo" = "  \"foo\"");    padding not done *)
+  test (sprintf "%1S" "foo" = "\"foo\"");
+(*  test (sprintf "%*S" 6 "foo" = "   \"foo\"");  padding not done *)
+  test (sprintf "%*S" 2 "foo" = "\"foo\"");
+(*  test (sprintf "%-0+ #5S" "foo" = "\"foo\"  ");  padding not done *)
+  test (sprintf "%S@" "foo" = "\"foo\"@");
+  test (sprintf "%S@inria.fr" "foo" = "\"foo\"@inria.fr");
+  test (sprintf "%S@%S" "foo" "inria.fr" = "\"foo\"@\"inria.fr\"");
+
+  printf "\nc\n%!";
+  test (sprintf "%c" 'c' = "c");
+(*  test (sprintf "%-4c" 'c' = "c   ");    padding not done *)
+(*  test (sprintf "%04c" 'c' = "   c");    padding not done *)
+  test (sprintf "%+c" 'c' = "c");
+  test (sprintf "% c" 'c' = "c");
+  test (sprintf "%#c" 'c' = "c");
+(*  test (sprintf "%4c" 'c' = "   c");     padding not done *)
+(*  test (sprintf "%*c" 2 'c' = " c");     padding not done *)
+(*  test (sprintf "%-0+ #4c" 'c' = "c   ");  padding not done *)
+
+  printf "\nC\n%!";
+  test (sprintf "%C" 'c' = "'c'");
+  test (sprintf "%C" '\'' = "'\\''");
+(*  test (sprintf "%-4C" 'c' = "c   ");    padding not done *)
+(*  test (sprintf "%04C" 'c' = "   c");    padding not done *)
+  test (sprintf "%+C" 'c' = "'c'");
+  test (sprintf "% C" 'c' = "'c'");
+  test (sprintf "%#C" 'c' = "'c'");
+(*  test (sprintf "%4C" 'c' = "   c");     padding not done *)
+(*  test (sprintf "%*C" 2 'c' = " c");     padding not done *)
+(*  test (sprintf "%-0+ #4C" 'c' = "c   ");  padding not done *)
+
+  printf "\nf\n%!";
+  test (sprintf "%f" (-42.42) = "-42.420000");
+  test (sprintf "%-13f" (-42.42) = "-42.420000   ");
+  test (sprintf "%013f" (-42.42) = "-00042.420000");
+  test (sprintf "%+f" 42.42 = "+42.420000");
+  test (sprintf "% f" 42.42 = " 42.420000");
+  test (sprintf "%#f" 42.42 = "42.420000");
+  test (sprintf "%13f" 42.42 = "    42.420000");
+  test (sprintf "%*f" 12 42.42 = "   42.420000");
+  test (sprintf "%-0+ #12f" 42.42 = "+42.420000  ");
+  test (sprintf "%.3f" (-42.42) = "-42.420");
+  test (sprintf "%-13.3f" (-42.42) = "-42.420      ");
+  test (sprintf "%013.3f" (-42.42) = "-00000042.420");
+  test (sprintf "%+.3f" 42.42 = "+42.420");
+  test (sprintf "% .3f" 42.42 = " 42.420");
+  test (sprintf "%#.3f" 42.42 = "42.420");
+  test (sprintf "%13.3f" 42.42 = "       42.420");
+  test (sprintf "%*.*f" 12 3 42.42 = "      42.420");
+  test (sprintf "%-0+ #12.3f" 42.42 = "+42.420     ");
+
+  printf "\nF\n%!";
+  test (sprintf "%F" 42.42 = "42.42");
+  test (sprintf "%F" 42.42e42 = "4.242e+43");
+  test (sprintf "%F" 42.00 = "42.");
+  test (sprintf "%F" 0.042 = "0.042");
+(* no padding, no precision
+  test (sprintf "%.3F" 42.42 = "42.420");
+  test (sprintf "%12.3F" 42.42e42 = "   4.242e+43");
+  test (sprintf "%.3F" 42.00 = "42.000");
+  test (sprintf "%.3F" 0.0042 = "0.004");
+*)
+
+  printf "\ne\n%!";
+  test (sprintf "%e" (-42.42) = "-4.242000e+01");
+  test (sprintf "%-15e" (-42.42) = "-4.242000e+01  ");
+  test (sprintf "%015e" (-42.42) = "-004.242000e+01");
+  test (sprintf "%+e" 42.42 = "+4.242000e+01");
+  test (sprintf "% e" 42.42 = " 4.242000e+01");
+  test (sprintf "%#e" 42.42 = "4.242000e+01");
+  test (sprintf "%15e" 42.42 = "   4.242000e+01");
+  test (sprintf "%*e" 14 42.42 = "  4.242000e+01");
+  test (sprintf "%-0+ #14e" 42.42 = "+4.242000e+01 ");
+  test (sprintf "%.3e" (-42.42) = "-4.242e+01");
+  test (sprintf "%-15.3e" (-42.42) = "-4.242e+01     ");
+  test (sprintf "%015.3e" (-42.42) = "-000004.242e+01");
+  test (sprintf "%+.3e" 42.42 = "+4.242e+01");
+  test (sprintf "% .3e" 42.42 = " 4.242e+01");
+  test (sprintf "%#.3e" 42.42 = "4.242e+01");
+  test (sprintf "%15.3e" 42.42 = "      4.242e+01");
+  test (sprintf "%*.*e" 11 3 42.42 = "  4.242e+01");
+  test (sprintf "%-0+ #14.3e" 42.42 = "+4.242e+01    ");
+
+  printf "\nE\n%!";
+  test (sprintf "%E" (-42.42) = "-4.242000E+01");
+  test (sprintf "%-15E" (-42.42) = "-4.242000E+01  ");
+  test (sprintf "%015E" (-42.42) = "-004.242000E+01");
+  test (sprintf "%+E" 42.42 = "+4.242000E+01");
+  test (sprintf "% E" 42.42 = " 4.242000E+01");
+  test (sprintf "%#E" 42.42 = "4.242000E+01");
+  test (sprintf "%15E" 42.42 = "   4.242000E+01");
+  test (sprintf "%*E" 14 42.42 = "  4.242000E+01");
+  test (sprintf "%-0+ #14E" 42.42 = "+4.242000E+01 ");
+  test (sprintf "%.3E" (-42.42) = "-4.242E+01");
+  test (sprintf "%-15.3E" (-42.42) = "-4.242E+01     ");
+  test (sprintf "%015.3E" (-42.42) = "-000004.242E+01");
+  test (sprintf "%+.3E" 42.42 = "+4.242E+01");
+  test (sprintf "% .3E" 42.42 = " 4.242E+01");
+  test (sprintf "%#.3E" 42.42 = "4.242E+01");
+  test (sprintf "%15.3E" 42.42 = "      4.242E+01");
+  test (sprintf "%*.*E" 11 3 42.42 = "  4.242E+01");
+  test (sprintf "%-0+ #14.3E" 42.42 = "+4.242E+01    ");
+
+(* %g gives strange results that correspond to neither %f nor %e
+  printf "\ng\n%!";
+  test (sprintf "%g" (-42.42) = "-42.42000");
+  test (sprintf "%-15g" (-42.42) = "-42.42000      ");
+  test (sprintf "%015g" (-42.42) = "-00000042.42000");
+  test (sprintf "%+g" 42.42 = "+42.42000");
+  test (sprintf "% g" 42.42 = " 42.42000");
+  test (sprintf "%#g" 42.42 = "42.42000");
+  test (sprintf "%15g" 42.42 = "       42.42000");
+  test (sprintf "%*g" 14 42.42 = "      42.42000");
+  test (sprintf "%-0+ #14g" 42.42 = "+42.42000     ");
+  test (sprintf "%.3g" (-42.42) = "-42.420");
+*)
+
+(* Same for %G
+  printf "\nG\n%!";
+*)
+
+  printf "\nB\n%!";
+  test (sprintf "%B" true = "true");
+  test (sprintf "%B" false = "false");
+
+  printf "\nld/li positive\n%!";
+  test (sprintf "%ld/%li" 42l 43l = "42/43");
+  test (sprintf "%-4ld/%-5li" 42l 43l = "42  /43   ");
+  test (sprintf "%04ld/%05li" 42l 43l = "0042/00043");
+  test (sprintf "%+ld/%+li" 42l 43l = "+42/+43");
+  test (sprintf "% ld/% li" 42l 43l = " 42/ 43");
+  test (sprintf "%#ld/%#li" 42l 43l = "42/43");
+  test (sprintf "%4ld/%5li" 42l 43l = "  42/   43");
+  test (sprintf "%*ld/%*li" 4 42l 5 43l = "  42/   43");
+  test (sprintf "%-0+#4ld/%-0 #5li" 42l 43l = "+42 / 43  ");
+
+  printf "\nld/li negative\n%!";
+  test (sprintf "%ld/%li" (-42l) (-43l) = "-42/-43");
+  test (sprintf "%-4ld/%-5li" (-42l) (-43l) = "-42 /-43  ");
+  test (sprintf "%04ld/%05li" (-42l) (-43l) = "-042/-0043");
+  test (sprintf "%+ld/%+li" (-42l) (-43l) = "-42/-43");
+  test (sprintf "% ld/% li" (-42l) (-43l) = "-42/-43");
+  test (sprintf "%#ld/%#li" (-42l) (-43l) = "-42/-43");
+  test (sprintf "%4ld/%5li" (-42l) (-43l) = " -42/  -43");
+  test (sprintf "%*ld/%*li" 4 (-42l) 5 (-43l) = " -42/  -43");
+  test (sprintf "%-0+ #4ld/%-0+ #5li" (-42l) (-43l) = "-42 /-43  ");
+
+  printf "\nlu positive\n%!";
+  test (sprintf "%lu" 42l = "42");
+  test (sprintf "%-4lu" 42l = "42  ");
+  test (sprintf "%04lu" 42l = "0042");
+  test (sprintf "%+lu" 42l = "42");
+  test (sprintf "% lu" 42l = "42");
+  test (sprintf "%#lu" 42l = "42");
+  test (sprintf "%4lu" 42l = "  42");
+  test (sprintf "%*lu" 4 42l = "  42");
+  test (sprintf "%-0+ #6ld" 42l = "+42   ");
+
+  printf "\nlu negative\n%!";
+  test (sprintf "%lu" (-1l) = "4294967295");
+
+  printf "\nlx positive\n%!";
+  test (sprintf "%lx" 42l = "2a");
+  test (sprintf "%-4lx" 42l = "2a  ");
+  test (sprintf "%04lx" 42l = "002a");
+  test (sprintf "%+lx" 42l = "2a");
+  test (sprintf "% lx" 42l = "2a");
+  test (sprintf "%#lx" 42l = "0x2a");
+  test (sprintf "%4lx" 42l = "  2a");
+  test (sprintf "%*lx" 5 42l = "   2a");
+  test (sprintf "%-0+ #*lx" 5 42l = "0x2a ");
+
+  printf "\nlx negative\n%!";
+  test (sprintf "%lx" (-42l) = "ffffffd6");
+
+  printf "\nlX positive\n%!";
+  test (sprintf "%lX" 42l = "2A");
+  test (sprintf "%-4lX" 42l = "2A  ");
+  test (sprintf "%04lX" 42l = "002A");
+  test (sprintf "%+lX" 42l = "2A");
+  test (sprintf "% lX" 42l = "2A");
+  test (sprintf "%#lX" 42l = "0X2A");
+  test (sprintf "%4lX" 42l = "  2A");
+  test (sprintf "%*lX" 5 42l = "   2A");
+  test (sprintf "%-0+ #*lX" 5 42l = "0X2A ");
+
+  printf "\nlx negative\n%!";
+  test (sprintf "%lX" (-42l) = "FFFFFFD6");
+
+  printf "\nlo positive\n%!";
+  test (sprintf "%lo" 42l = "52");
+  test (sprintf "%-4lo" 42l = "52  ");
+  test (sprintf "%04lo" 42l = "0052");
+  test (sprintf "%+lo" 42l = "52");
+  test (sprintf "% lo" 42l = "52");
+  test (sprintf "%#lo" 42l = "052");
+  test (sprintf "%4lo" 42l = "  52");
+  test (sprintf "%*lo" 5 42l = "   52");
+  test (sprintf "%-0+ #*lo" 5 42l = "052  ");
+
+  printf "\nlo negative\n%!";
+  test (sprintf "%lo" (-42l) = "37777777726");
+
+  (* Nativeint not tested: looks like too much work, and anyway it should
+     work like Int32 or Int64. *)
+
+  printf "\nLd/Li positive\n%!";
+  test (sprintf "%Ld/%Li" 42L 43L = "42/43");
+  test (sprintf "%-4Ld/%-5Li" 42L 43L = "42  /43   ");
+  test (sprintf "%04Ld/%05Li" 42L 43L = "0042/00043");
+  test (sprintf "%+Ld/%+Li" 42L 43L = "+42/+43");
+  test (sprintf "% Ld/% Li" 42L 43L = " 42/ 43");
+  test (sprintf "%#Ld/%#Li" 42L 43L = "42/43");
+  test (sprintf "%4Ld/%5Li" 42L 43L = "  42/   43");
+  test (sprintf "%*Ld/%*Li" 4 42L 5 43L = "  42/   43");
+  test (sprintf "%-0+#4Ld/%-0 #5Li" 42L 43L = "+42 / 43  ");
+
+  printf "\nLd/Li negative\n%!";
+  test (sprintf "%Ld/%Li" (-42L) (-43L) = "-42/-43");
+  test (sprintf "%-4Ld/%-5Li" (-42L) (-43L) = "-42 /-43  ");
+  test (sprintf "%04Ld/%05Li" (-42L) (-43L) = "-042/-0043");
+  test (sprintf "%+Ld/%+Li" (-42L) (-43L) = "-42/-43");
+  test (sprintf "% Ld/% Li" (-42L) (-43L) = "-42/-43");
+  test (sprintf "%#Ld/%#Li" (-42L) (-43L) = "-42/-43");
+  test (sprintf "%4Ld/%5Li" (-42L) (-43L) = " -42/  -43");
+  test (sprintf "%*Ld/%*Li" 4 (-42L) 5 (-43L) = " -42/  -43");
+  test (sprintf "%-0+ #4Ld/%-0+ #5Li" (-42L) (-43L) = "-42 /-43  ");
+
+  printf "\nLu positive\n%!";
+  test (sprintf "%Lu" 42L = "42");
+  test (sprintf "%-4Lu" 42L = "42  ");
+  test (sprintf "%04Lu" 42L = "0042");
+  test (sprintf "%+Lu" 42L = "42");
+  test (sprintf "% Lu" 42L = "42");
+  test (sprintf "%#Lu" 42L = "42");
+  test (sprintf "%4Lu" 42L = "  42");
+  test (sprintf "%*Lu" 4 42L = "  42");
+  test (sprintf "%-0+ #6Ld" 42L = "+42   ");
+
+  printf "\nLu negative\n%!";
+  test (sprintf "%Lu" (-1L) = "18446744073709551615");
+
+  printf "\nLx positive\n%!";
+  test (sprintf "%Lx" 42L = "2a");
+  test (sprintf "%-4Lx" 42L = "2a  ");
+  test (sprintf "%04Lx" 42L = "002a");
+  test (sprintf "%+Lx" 42L = "2a");
+  test (sprintf "% Lx" 42L = "2a");
+  test (sprintf "%#Lx" 42L = "0x2a");
+  test (sprintf "%4Lx" 42L = "  2a");
+  test (sprintf "%*Lx" 5 42L = "   2a");
+  test (sprintf "%-0+ #*Lx" 5 42L = "0x2a ");
+
+  printf "\nLx negative\n%!";
+  test (sprintf "%Lx" (-42L) = "ffffffffffffffd6");
+
+  printf "\nLX positive\n%!";
+  test (sprintf "%LX" 42L = "2A");
+  test (sprintf "%-4LX" 42L = "2A  ");
+  test (sprintf "%04LX" 42L = "002A");
+  test (sprintf "%+LX" 42L = "2A");
+  test (sprintf "% LX" 42L = "2A");
+  test (sprintf "%#LX" 42L = "0X2A");
+  test (sprintf "%4LX" 42L = "  2A");
+  test (sprintf "%*LX" 5 42L = "   2A");
+  test (sprintf "%-0+ #*LX" 5 42L = "0X2A ");
+
+  printf "\nLx negative\n%!";
+  test (sprintf "%LX" (-42L) = "FFFFFFFFFFFFFFD6");
+
+  printf "\nLo positive\n%!";
+  test (sprintf "%Lo" 42L = "52");
+  test (sprintf "%-4Lo" 42L = "52  ");
+  test (sprintf "%04Lo" 42L = "0052");
+  test (sprintf "%+Lo" 42L = "52");
+  test (sprintf "% Lo" 42L = "52");
+  test (sprintf "%#Lo" 42L = "052");
+  test (sprintf "%4Lo" 42L = "  52");
+  test (sprintf "%*Lo" 5 42L = "   52");
+  test (sprintf "%-0+ #*Lo" 5 42L = "052  ");
+
+  printf "\nLo negative\n%!";
+  test (sprintf "%Lo" (-42L) = "1777777777777777777726");
+
+  printf "\na\n%!";
+  let x = ref () in
+  let f () y = if y == x then "ok" else "wrong" in
+  test (sprintf "%a" f x = "ok");
+
+  printf "\nt\n%!";
+  let f () = "ok" in
+  test (sprintf "%t" f = "ok");
+
+(* Does not work as expected.  Should be fixed to work like %s.
+  printf "\n{...%%}\n%!";
+  let f = format_of_string "%f/%s" in
+  test (sprintf "%{%f%s%}" f = "%f/%s");
+*)
+
+  printf "\n(...%%)\n%!";
+  let f = format_of_string "%d/foo/%s" in
+  test (sprintf "%(%d%s%)" f 42 "bar" = "42/foo/bar");
+
+  printf "\n! %% @ , and constants\n%!";
+  test (sprintf "%!" = "");
+  test (sprintf "%%" = "%");
+  test (sprintf "%@" = "@");
+  test (sprintf "%," = "");
+  test (sprintf "@" = "@");
+  test (sprintf "@@" = "@@");
+  test (sprintf "@%%" = "@%");
+
+  printf "\nend of tests\n%!";
+with e ->
+  printf "unexpected exception: %s\n%!" (Printexc.to_string e);
+  test false;
+;;
diff --git a/testsuite/tests/lib-format/tformat.reference b/testsuite/tests/lib-format/tformat.reference
new file mode 100644
index 000000000..c30013eb6
--- /dev/null
+++ b/testsuite/tests/lib-format/tformat.reference
@@ -0,0 +1,89 @@
+d/i positive
+ 0 1 2 3 4 5 6 7 8
+d/i negative
+ 9 10 11 12 13 14 15 16 17
+u positive
+ 18 19 20 21 22 23 24 25 26
+u negative
+ 27
+x positive
+ 28 29 30 31 32 33 34 35 36
+x negative
+ 37
+X positive
+ 38 39 40 41 42 43 44 45 46
+x negative
+ 47
+o positive
+ 48 49 50 51 52 53 54 55 56
+o negative
+ 57
+s
+ 58 59 60 61 62 63 64 65 66 67 68 69 70 71
+S
+ 72 73 74 75 76 77 78 79 80
+c
+ 81 82 83 84
+C
+ 85 86 87 88 89
+f
+ 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107
+F
+ 108 109 110 111
+e
+ 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129
+E
+ 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147
+B
+ 148 149
+ld/li positive
+ 150 151 152 153 154 155 156 157 158
+ld/li negative
+ 159 160 161 162 163 164 165 166 167
+lu positive
+ 168 169 170 171 172 173 174 175 176
+lu negative
+ 177
+lx positive
+ 178 179 180 181 182 183 184 185 186
+lx negative
+ 187
+lX positive
+ 188 189 190 191 192 193 194 195 196
+lx negative
+ 197
+lo positive
+ 198 199 200 201 202 203 204 205 206
+lo negative
+ 207
+Ld/Li positive
+ 208 209 210 211 212 213 214 215 216
+Ld/Li negative
+ 217 218 219 220 221 222 223 224 225
+Lu positive
+ 226 227 228 229 230 231 232 233 234
+Lu negative
+ 235
+Lx positive
+ 236 237 238 239 240 241 242 243 244
+Lx negative
+ 245
+LX positive
+ 246 247 248 249 250 251 252 253 254
+Lx negative
+ 255
+Lo positive
+ 256 257 258 259 260 261 262 263 264
+Lo negative
+ 265
+a
+ 266
+t
+ 267
+(...%)
+ 268
+! % @ , and constants
+ 269 270 271 272 273 274 275
+end of tests
+
+All tests succeeded.