reftable: utility functions

This commit provides basic utility classes for the reftable library.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

reftable/test_framework.c

@@ -0,0 +1,23 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "system.h"
+#include "test_framework.h"
+
+#include "basics.h"
+
+void set_test_hash(uint8_t *p, int i)
+{
+	memset(p, (uint8_t)i, hash_size(GIT_SHA1_FORMAT_ID));
+}
+
+ssize_t strbuf_add_void(void *b, const void *data, size_t sz)
+{
+	strbuf_add(b, data, sz);
+	return sz;
+}