diff --git a/Makefile b/Makefile
index 9f0aac9..0a372cb 100644
--- a/Makefile
+++ b/Makefile
@@ -101,6 +101,7 @@ dist:
 		$(PACKAGE)-$(VERSION)/tests/variable.c \
 		$(PACKAGE)-$(VERSION)/tests/COPYING \
 		$(PACKAGE)-$(VERSION)/tests/Makefile \
+		$(PACKAGE)-$(VERSION)/tests/python.sh \
 		$(PACKAGE)-$(VERSION)/tests/tests.sh \
 		$(PACKAGE)-$(VERSION)/tests/project.conf \
 		$(PACKAGE)-$(VERSION)/tools/configctl.c \
diff --git a/include/System/string.h b/include/System/string.h
index 7f0bdb0..3d45bca 100644
--- a/include/System/string.h
+++ b/include/System/string.h
@@ -34,6 +34,7 @@ typedef char String;
 /* functions */
 String * string_new(String const * string);
 String * string_new_append(String const * string, ...);
+String * string_new_format(String const * format, ...);
 String * string_new_length(String const * string, size_t length);
 void string_delete(String * string);
 
diff --git a/src/string.c b/src/string.c
index 8242628..15acf07 100644
--- a/src/string.c
+++ b/src/string.c
@@ -13,7 +13,7 @@
  * You should have received a copy of the GNU Lesser General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>. */
 /* TODO:
- * - add string_new_format(), string_rtrim(), string_ltrim()... */
+ * - add string_rtrim(), string_ltrim()... */
 
 
 
@@ -68,6 +68,37 @@ String * string_new_append(String const * string, ...)
 }
 
 
+/* string_new_format */
+String * string_new_format(String const * format, ...)
+{
+	String * ret;
+	va_list ap;
+	int len;
+	size_t s;
+
+	va_start(ap, format);
+	len = vsnprintf(NULL, 0, format, ap);
+	va_end(ap);
+	if(len < 0)
+	{
+		error_set_code(1, "%s", strerror(errno));
+		return NULL;
+	}
+	s = (size_t)len + 1;
+	if((ret = object_new(s)) == NULL)
+		return NULL;
+	va_start(ap, format);
+	if(vsnprintf(ret, s, format, ap) != len)
+	{
+		error_set_code(1, "%s", strerror(errno));
+		object_delete(ret);
+		ret = NULL;
+	}
+	va_end(ap);
+	return ret;
+}
+
+
 /* string_new_length */
 String * string_new_length(String const * string, size_t length)
 {
diff --git a/tests/Makefile b/tests/Makefile
index ed6c3ea..f445583 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -39,7 +39,7 @@ variable_LDFLAGS = $(LDFLAGSF) $(LDFLAGS)
 variable: $(variable_OBJS)
 	$(CC) -o variable $(variable_OBJS) $(variable_LDFLAGS)
 
-tests.log: includes string tests.sh variable
+tests.log: includes python.sh string tests.sh variable
 	./tests.sh -P "$(PREFIX)" -- "tests.log"
 
 includes.o: includes.c
diff --git a/tests/project.conf b/tests/project.conf
index 4727179..e298f6c 100644
--- a/tests/project.conf
+++ b/tests/project.conf
@@ -4,7 +4,7 @@ cflags_force=-W
 cflags=-Wall -g -O2
 ldflags_force=-L ../src -lSystem
 ldflags=-L$(PREFIX)/lib -Wl,-rpath,"$(PWD)/../src"
-dist=COPYING,Makefile,tests.sh
+dist=COPYING,Makefile,python.sh,tests.sh
 
 [includes]
 type=binary
@@ -20,7 +20,7 @@ depends=../src/string.c
 [tests.log]
 type=script
 script=./tests.sh
-depends=includes,string,tests.sh,variable
+depends=includes,python.sh,string,tests.sh,variable
 
 [variable]
 type=binary
diff --git a/tests/python.sh b/tests/python.sh
new file mode 100755
index 0000000..19561ed
--- /dev/null
+++ b/tests/python.sh
@@ -0,0 +1,24 @@
+#!/bin/sh
+#$Id$
+#Copyright (c) 2014 Pierre Pronchery <khorben@defora.org>
+#This file is part of DeforaOS System libSystem
+#This program is free software: you can redistribute it and/or modify
+#it under the terms of the GNU General Public License as published by
+#the Free Software Foundation, version 3 of the License.
+#
+#This program is distributed in the hope that it will be useful,
+#but WITHOUT ANY WARRANTY; without even the implied warranty of
+#MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#GNU General Public License for more details.
+#
+#You should have received a copy of the GNU General Public License
+#along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+
+#variables
+#executables
+MAKE="make"
+
+
+(cd ../src/python && $MAKE clean all)
diff --git a/tests/string.c b/tests/string.c
index bb7c447..e6dcbb4 100644
--- a/tests/string.c
+++ b/tests/string.c
@@ -30,6 +30,7 @@ static int _test(char const * progname, String * s)
 	printf("%s: Testing %s\n", progname, "string_get_length()");
 	if((len = string_get_length(s)) == 0)
 		return 2;
+	printf("\"%s\" => %lu\n", s, len);
 	/* string_clear */
 	printf("%s: Testing %s\n", progname, "string_clear()");
 	string_clear(s);
@@ -50,5 +51,9 @@ int main(int argc, char * argv[])
 		return 2;
 	ret |= _test(argv[0], s);
 	string_delete(s);
+	if((s = string_new_format("%s", argv[0])) == NULL)
+		return 2;
+	ret |= _test(argv[0], s);
+	string_delete(s);
 	return 0;
 }
diff --git a/tests/tests.sh b/tests/tests.sh
index 1829c7a..5d1c7d3 100755
--- a/tests/tests.sh
+++ b/tests/tests.sh
@@ -101,6 +101,8 @@ echo "Performing tests:" 1>&2
 _test "includes"
 _test "string"
 _test "variable"
+echo "Expected failures:" 1>&2
+_fail "python.sh"
 if [ -n "$FAILED" ]; then
 	echo "Failed tests:$FAILED" 1>&2
 	exit 2