diff --git a/t/unit-tests/u-reftable-readwrite.c b/t/unit-tests/u-reftable-readwrite.c
new file mode 100644
index 0000000000..3d6bdcfceb
--- /dev/null
+++ b/t/unit-tests/u-reftable-readwrite.c

@@ -0,0 +1,870 @@
+/*
+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
+*/
+
+#define DISABLE_SIGN_COMPARE_WARNINGS
+
+#include "unit-test.h"
+#include "lib-reftable.h"
+#include "reftable/basics.h"
+#include "reftable/blocksource.h"
+#include "reftable/reader.h"
+#include "reftable/reftable-error.h"
+#include "reftable/reftable-writer.h"
+#include "strbuf.h"
+
+static const int update_index = 5;
+
+void test_reftable_readwrite__buffer(void)
+{
+	struct reftable_buf buf = REFTABLE_BUF_INIT;
+	struct reftable_block_source source = { 0 };
+	struct reftable_block out = { 0 };
+	int n;
+	uint8_t in[] = "hello";
+	cl_assert(reftable_buf_add(&buf, in, sizeof(in)) == 0);
+	block_source_from_buf(&source, &buf);
+	cl_assert_equal_i(block_source_size(&source), 6);
+	n = block_source_read_block(&source, &out, 0, sizeof(in));
+	cl_assert_equal_i(n, sizeof(in));
+	cl_assert(memcmp(in, out.data, n) == 0);