diff --git a/tests/Makefile.am b/tests/Makefile.am
index 1de7723..e2854dd 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -3,12 +3,26 @@ include ../Makefile.am.inc
 
 LIBJSON_LA=$(top_builddir)/libjson.la
 
-check_PROGRAMS = test1 test2 test4 test_parse_int64 test_null test_cast test_parse
+check_PROGRAMS = test1 test1Formatted 
+check_PROGRAMS += test2 test2Formatted
+check_PROGRAMS += test4
+check_PROGRAMS += test_parse_int64
+check_PROGRAMS += test_null
+check_PROGRAMS += test_cast
+check_PROGRAMS += test_parse
 
 test1_LDADD = $(LIBJSON_LA)
 
+test1Formatted_LDADD= $(LIBJSON_LA)
+test1Formatted_SOURCES = test1.c parse_flags.c
+test1Formatted_CPPFLAGS = -DTEST_FORMATTED
+
 test2_LDADD = $(LIBJSON_LA)
 
+test2Formatted_LDADD= $(LIBJSON_LA)
+test2Formatted_SOURCES = test2.c parse_flags.c
+test2Formatted_CPPFLAGS = -DTEST_FORMATTED
+
 test4_LDADD = $(LIBJSON_LA)
 
 test_parse_int64_LDADD = $(LIBJSON_LA)
diff --git a/tests/parse_flags.c b/tests/parse_flags.c
new file mode 100644
index 0000000..fafabc8
--- /dev/null
+++ b/tests/parse_flags.c
@@ -0,0 +1,42 @@
+#include <stdio.h>
+#include <string.h>
+
+#include "json.h"
+#include "parse_flags.h"
+
+static struct {
+	const char *arg;
+	int flag;
+} format_args[] = {
+	{ "plain", JSON_C_TO_STRING_PLAIN },
+	{ "spaced", JSON_C_TO_STRING_SPACED },
+	{ "pretty", JSON_C_TO_STRING_PRETTY },
+};
+
+#ifndef NELEM
+#define NELEM(x) (sizeof(x) / sizeof(&x[0]))
+#endif
+
+int parse_flags(int argc, char **argv)
+{
+	int arg_idx;
+	int sflags = 0;
+	for (arg_idx = 1; arg_idx < argc ; arg_idx++)
+	{
+		int jj;
+		for (jj = 0; jj < NELEM(format_args); jj++)
+		{
+			if (strcasecmp(argv[arg_idx], format_args[jj].arg) == 0)
+			{
+				sflags |= format_args[jj].flag;
+				break;
+			}
+		}
+		if (jj == NELEM(format_args))
+		{
+			printf("Unknown arg: %s\n", argv[arg_idx]);
+			exit(1);
+		}
+	}
+	return sflags;
+}
diff --git a/tests/parse_flags.h b/tests/parse_flags.h
new file mode 100644
index 0000000..c5e2f41
--- /dev/null
+++ b/tests/parse_flags.h
@@ -0,0 +1,4 @@
+#ifndef __parse_flags_h
+#define __parse_flags_h
+int parse_flags(int argc, char **argv);
+#endif
diff --git a/tests/test-defs.sh b/tests/test-defs.sh
index b9b0f60..658a75d 100755
--- a/tests/test-defs.sh
+++ b/tests/test-defs.sh
@@ -26,22 +26,24 @@ top_builddir=${top_builddir}/tests
 progname=`echo "$0" | sed 's,^.*/,,'`
 testname=`echo "$progname" | sed 's,-.*$,,'`
 testsubdir=${testsubdir-testSubDir}
+testsubdir=${testsubdir}/${progname}
 
 # User can set VERBOSE to cause output redirection
 case "$VERBOSE" in
 [Nn]|[Nn][Oo]|0|"")
 	VERBOSE=0
-	exec > /dev/null 2>&1
+	exec > /dev/null
 	;;
 [Yy]|[Yy][Ee][Ss])
 	VERBOSE=1
 	;;
 esac
 
-rm -rf "$testsubdir/$progname" > /dev/null 2>&1
-mkdir -p "$testsubdir/$progname"
-cd "$testsubdir/$progname" \
-   || { echo "Cannot make or change into $testsubdir/$progname"; exit 1; }
+rm -rf "$testsubdir" > /dev/null 2>&1
+mkdir -p "$testsubdir"
+CURDIR=$(pwd)
+cd "$testsubdir" \
+   || { echo "Cannot make or change into $testsubdir"; exit 1; }
 
 echo "=== Running test $progname"
 
@@ -68,44 +70,55 @@ fi
 #
 run_output_test()
 {
+	if [ "$1" = "-o" ] ; then
+		TEST_OUTPUT="$2"
+		shift
+		shift
+	fi
 	TEST_COMMAND="$1"
+	shift
+	if [ -z "${TEST_OUTPUT}" ] ; then	
+		TEST_OUTPUT=${TEST_COMMAND}
+	fi
 
-	REDIR_OUTPUT="> \"${TEST_COMMAND}.out\""
+	REDIR_OUTPUT="> \"${TEST_OUTPUT}.out\""
 	if [ $VERBOSE -gt 1 ] ; then
-		REDIR_OUTPUT="| tee \"${TEST_COMMAND}.out\""
+		REDIR_OUTPUT="| tee \"${TEST_OUTPUT}.out\""
 	fi
 
 	if [ $use_valgrind -eq 1 ] ; then
 		eval valgrind --tool=memcheck \
 			--trace-children=yes \
 			--demangle=yes \
-			--log-file=vg.out \
+			--log-file="${TEST_OUTPUT}.vg.out" \
 			--leak-check=full \
 			--show-reachable=yes \
 			--run-libc-freeres=yes \
-		"\"${top_builddir}/${TEST_COMMAND}\"" ${REDIR_OUTPUT}
+		"\"${top_builddir}/${TEST_COMMAND}\"" \"\$@\" ${REDIR_OUTPUT}
 		err=$?
 
 	else
-		eval "\"${top_builddir}/${TEST_COMMAND}"\" ${REDIR_OUTPUT}
+		eval "\"${top_builddir}/${TEST_COMMAND}"\" \"\$@\" ${REDIR_OUTPUT}
 		err=$?
 	fi
 
 	if [ $err -ne 0 ] ; then
-		echo "ERROR: ${TEST_COMMAND} exited with non-zero exit status: $err" 1>&2
+		echo "ERROR: \"${TEST_COMMAND} $@\" exited with non-zero exit status: $err" 1>&2
 	fi
 
 	if [ $use_valgrind -eq 1 ] ; then
-		if ! tail -1 "vg.out" | grep -q "ERROR SUMMARY: 0 errors" ; then
+		if ! tail -1 "${TEST_OUTPUT}.vg.out" | grep -q "ERROR SUMMARY: 0 errors" ; then
 			echo "ERROR: valgrind found errors during execution:" 1>&2
-			cat vg.out
+			cat "${TEST_OUTPUT}.vg.out"
 			err=1
 		fi
 	fi
 
-	if ! "$CMP" -s "${top_builddir}/${TEST_COMMAND}.expected" "${TEST_COMMAND}.out" ; then
-		echo "ERROR: ${TEST_COMMAND} failed:" 1>&2
-		diff "${top_builddir}/${TEST_COMMAND}.expected" "${TEST_COMMAND}.out" 1>&2
+	if ! "$CMP" -s "${top_builddir}/${TEST_OUTPUT}.expected" "${TEST_OUTPUT}.out" ; then
+		echo "ERROR: \"${TEST_COMMAND} $@\" (${TEST_OUTPUT}) failed (set VERBOSE=1 to see full output):" 1>&2
+		(cd "${CURDIR}" ; set -x ; diff "${top_builddir}/${TEST_OUTPUT}.expected" "$testsubdir/${TEST_OUTPUT}.out")
+		echo "cp \"$testsubdir/${TEST_OUTPUT}.out\" \"${top_builddir}/${TEST_OUTPUT}.expected\"" 1>&2
+
 		err=1
 	fi
 
diff --git a/tests/test1.c b/tests/test1.c
index e1e411d..9802eb1 100644
--- a/tests/test1.c
+++ b/tests/test1.c
@@ -5,6 +5,7 @@
 #include <assert.h>
 
 #include "json.h"
+#include "parse_flags.h"
 
 static int sort_fn (const void *j1, const void *j2)
 {
@@ -29,13 +30,26 @@ static int sort_fn (const void *j1, const void *j2)
   return i1 - i2;
 }
 
+#ifdef TEST_FORMATTED
+#define json_object_to_json_string(obj) json_object_to_json_string_ext(obj,sflags)
+#else
+/* no special define */
+#endif
+
 int main(int argc, char **argv)
 {
   json_object *my_string, *my_int, *my_object, *my_array;
   int i;
+#ifdef TEST_FORMATTED
+	int sflags = 0;
+#endif
 
   MC_SET_DEBUG(1);
 
+#ifdef TEST_FORMATTED
+	sflags = parse_flags(argc, argv);
+#endif
+
   my_string = json_object_new_string("\t");
   printf("my_string=%s\n", json_object_get_string(my_string));
   printf("my_string.to_string()=%s\n", json_object_to_json_string(my_string));
diff --git a/tests/test1.test b/tests/test1.test
index 6074fac..79d2e09 100755
--- a/tests/test1.test
+++ b/tests/test1.test
@@ -9,4 +9,14 @@ fi
 . "$srcdir/test-defs.sh"
 
 run_output_test test1
-exit $?
+_err=$?
+
+for flag in plain spaced pretty ; do
+	run_output_test -o test1Formatted_${flag} test1Formatted ${flag}
+	_err2=$?
+	if [ $_err -eq 0 ] ; then
+		_err=$_err2
+	fi
+done
+
+exit $_err
diff --git a/tests/test1Formatted_plain.expected b/tests/test1Formatted_plain.expected
new file mode 100644
index 0000000..65b19ed
--- /dev/null
+++ b/tests/test1Formatted_plain.expected
@@ -0,0 +1,35 @@
+my_string=	
+my_string.to_string()="\t"
+my_string=\
+my_string.to_string()="\\"
+my_string=foo
+my_string.to_string()="foo"
+my_int=9
+my_int.to_string()=9
+my_array=
+	[0]=1
+	[1]=2
+	[2]=3
+	[3]=null
+	[4]=5
+my_array.to_string()=[1,2,3,null,5]
+my_array=
+	[0]=3
+	[1]=1
+	[2]=2
+	[3]=null
+	[4]=0
+my_array.to_string()=[3,1,2,null,0]
+my_array=
+	[0]=null
+	[1]=0
+	[2]=1
+	[3]=2
+	[4]=3
+my_array.to_string()=[null,0,1,2,3]
+my_object=
+	abc: 12
+	foo: "bar"
+	bool0: false
+	bool1: true
+my_object.to_string()={"abc":12,"foo":"bar","bool0":false,"bool1":true}
diff --git a/tests/test1Formatted_pretty.expected b/tests/test1Formatted_pretty.expected
new file mode 100644
index 0000000..f2334c4
--- /dev/null
+++ b/tests/test1Formatted_pretty.expected
@@ -0,0 +1,58 @@
+my_string=	
+my_string.to_string()="\t"
+my_string=\
+my_string.to_string()="\\"
+my_string=foo
+my_string.to_string()="foo"
+my_int=9
+my_int.to_string()=9
+my_array=
+	[0]=1
+	[1]=2
+	[2]=3
+	[3]=null
+	[4]=5
+my_array.to_string()=[
+  1,
+  2,
+  3,
+  null,
+  5
+]
+my_array=
+	[0]=3
+	[1]=1
+	[2]=2
+	[3]=null
+	[4]=0
+my_array.to_string()=[
+  3,
+  1,
+  2,
+  null,
+  0
+]
+my_array=
+	[0]=null
+	[1]=0
+	[2]=1
+	[3]=2
+	[4]=3
+my_array.to_string()=[
+  null,
+  0,
+  1,
+  2,
+  3
+]
+my_object=
+	abc: 12
+	foo: "bar"
+	bool0: false
+	bool1: true
+my_object.to_string()={
+  "abc":12,
+  "foo":"bar",
+  "bool0":false,
+  "bool1":true
+}
diff --git a/tests/test1Formatted_spaced.expected b/tests/test1Formatted_spaced.expected
new file mode 100644
index 0000000..6653fe0
--- /dev/null
+++ b/tests/test1Formatted_spaced.expected
@@ -0,0 +1,35 @@
+my_string=	
+my_string.to_string()="\t"
+my_string=\
+my_string.to_string()="\\"
+my_string=foo
+my_string.to_string()="foo"
+my_int=9
+my_int.to_string()=9
+my_array=
+	[0]=1
+	[1]=2
+	[2]=3
+	[3]=null
+	[4]=5
+my_array.to_string()=[ 1, 2, 3, null, 5 ]
+my_array=
+	[0]=3
+	[1]=1
+	[2]=2
+	[3]=null
+	[4]=0
+my_array.to_string()=[ 3, 1, 2, null, 0 ]
+my_array=
+	[0]=null
+	[1]=0
+	[2]=1
+	[3]=2
+	[4]=3
+my_array.to_string()=[ null, 0, 1, 2, 3 ]
+my_object=
+	abc: 12
+	foo: "bar"
+	bool0: false
+	bool1: true
+my_object.to_string()={ "abc": 12, "foo": "bar", "bool0": false, "bool1": true }
diff --git a/tests/test2.c b/tests/test2.c
index 5f95565..4a6b660 100644
--- a/tests/test2.c
+++ b/tests/test2.c
@@ -4,14 +4,28 @@
 #include <string.h>
 
 #include "json.h"
+#include "parse_flags.h"
+
+#ifdef TEST_FORMATTED
+#define json_object_to_json_string(obj) json_object_to_json_string_ext(obj,sflags)
+#else
+/* no special define */
+#endif
 
 
 int main(int argc, char **argv)
 {
   json_object *new_obj;
+#ifdef TEST_FORMATTED
+	int sflags = 0;
+#endif
 
   MC_SET_DEBUG(1);
 
+#ifdef TEST_FORMATTED
+	sflags = parse_flags(argc, argv);
+#endif
+
   new_obj = json_tokener_parse("/* more difficult test case */ { \"glossary\": { \"title\": \"example glossary\", \"GlossDiv\": { \"title\": \"S\", \"GlossList\": [ { \"ID\": \"SGML\", \"SortAs\": \"SGML\", \"GlossTerm\": \"Standard Generalized Markup Language\", \"Acronym\": \"SGML\", \"Abbrev\": \"ISO 8879:1986\", \"GlossDef\": \"A meta-markup language, used to create markup languages such as DocBook.\", \"GlossSeeAlso\": [\"GML\", \"XML\", \"markup\"] } ] } } }");
   printf("new_obj.to_string()=%s\n", json_object_to_json_string(new_obj));
   json_object_put(new_obj);
diff --git a/tests/test2.test b/tests/test2.test
index cbb3830..d4a4e79 100755
--- a/tests/test2.test
+++ b/tests/test2.test
@@ -9,4 +9,14 @@ fi
 . "$srcdir/test-defs.sh"
 
 run_output_test test2
-exit $?
+_err=$?
+
+for flag in plain spaced pretty ; do
+	run_output_test -o test2Formatted_${flag} test2Formatted ${flag}
+	_err2=$?
+	if [ $_err -eq 0 ] ; then
+		_err=$_err2
+	fi
+done
+
+exit $_err
diff --git a/tests/test2Formatted_plain.expected b/tests/test2Formatted_plain.expected
new file mode 100644
index 0000000..cc587e9
--- /dev/null
+++ b/tests/test2Formatted_plain.expected
@@ -0,0 +1 @@
+new_obj.to_string()={"glossary":{"title":"example glossary","GlossDiv":{"title":"S","GlossList":[{"ID":"SGML","SortAs":"SGML","GlossTerm":"Standard Generalized Markup Language","Acronym":"SGML","Abbrev":"ISO 8879:1986","GlossDef":"A meta-markup language, used to create markup languages such as DocBook.","GlossSeeAlso":["GML","XML","markup"]}]}}}
diff --git a/tests/test2Formatted_pretty.expected b/tests/test2Formatted_pretty.expected
new file mode 100644
index 0000000..8d6d740
--- /dev/null
+++ b/tests/test2Formatted_pretty.expected
@@ -0,0 +1,23 @@
+new_obj.to_string()={
+  "glossary":{
+    "title":"example glossary",
+    "GlossDiv":{
+      "title":"S",
+      "GlossList":[
+        {
+          "ID":"SGML",
+          "SortAs":"SGML",
+          "GlossTerm":"Standard Generalized Markup Language",
+          "Acronym":"SGML",
+          "Abbrev":"ISO 8879:1986",
+          "GlossDef":"A meta-markup language, used to create markup languages such as DocBook.",
+          "GlossSeeAlso":[
+            "GML",
+            "XML",
+            "markup"
+          ]
+        }
+      ]
+    }
+  }
+}
diff --git a/tests/test2Formatted_spaced.expected b/tests/test2Formatted_spaced.expected
new file mode 100644
index 0000000..0b740a9
--- /dev/null
+++ b/tests/test2Formatted_spaced.expected
@@ -0,0 +1 @@
+new_obj.to_string()={ "glossary": { "title": "example glossary", "GlossDiv": { "title": "S", "GlossList": [ { "ID": "SGML", "SortAs": "SGML", "GlossTerm": "Standard Generalized Markup Language", "Acronym": "SGML", "Abbrev": "ISO 8879:1986", "GlossDef": "A meta-markup language, used to create markup languages such as DocBook.", "GlossSeeAlso": [ "GML", "XML", "markup" ] } ] } } }