diff --git a/Makefile b/Makefile
index f6b344cd8ac..65d3856aaea 100644
--- a/Makefile
+++ b/Makefile
@@ -2453,6 +2453,7 @@ REFTABLE_OBJS += reftable/writer.o
 REFTABLE_TEST_OBJS += reftable/basics_test.o
 REFTABLE_TEST_OBJS += reftable/block_test.o
 REFTABLE_TEST_OBJS += reftable/record_test.o
+REFTABLE_TEST_OBJS += reftable/readwrite_test.o
 REFTABLE_TEST_OBJS += reftable/test_framework.o
 REFTABLE_TEST_OBJS += reftable/tree_test.o
 
diff --git a/reftable/readwrite_test.c b/reftable/readwrite_test.c
new file mode 100644
index 00000000000..5f6bcc2f775
--- /dev/null
+++ b/reftable/readwrite_test.c
@@ -0,0 +1,652 @@
+/*
+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 "basics.h"
+#include "block.h"
+#include "blocksource.h"
+#include "constants.h"
+#include "reader.h"
+#include "record.h"
+#include "test_framework.h"
+#include "reftable-tests.h"
+#include "reftable-writer.h"
+
+static const int update_index = 5;
+
+static void test_buffer(void)
+{
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_block_source source = { NULL };
+	struct reftable_block out = { NULL };
+	int n;
+	uint8_t in[] = "hello";
+	strbuf_add(&buf, in, sizeof(in));
+	block_source_from_strbuf(&source, &buf);
+	EXPECT(block_source_size(&source) == 6);
+	n = block_source_read_block(&source, &out, 0, sizeof(in));
+	EXPECT(n == sizeof(in));
+	EXPECT(!memcmp(in, out.data, n));
+	reftable_block_done(&out);
+
+	n = block_source_read_block(&source, &out, 1, 2);
+	EXPECT(n == 2);
+	EXPECT(!memcmp(out.data, "el", 2));
+
+	reftable_block_done(&out);
+	block_source_close(&source);
+	strbuf_release(&buf);
+}
+
+static void write_table(char ***names, struct strbuf *buf, int N,
+			int block_size, uint32_t hash_id)
+{
+	struct reftable_write_options opts = {
+		.block_size = block_size,
+		.hash_id = hash_id,
+	};
+	struct reftable_writer *w =
+		reftable_new_writer(&strbuf_add_void, buf, &opts);
+	struct reftable_ref_record ref = { NULL };
+	int i = 0, n;
+	struct reftable_log_record log = { NULL };
+	const struct reftable_stats *stats = NULL;
+	*names = reftable_calloc(sizeof(char *) * (N + 1));
+	reftable_writer_set_limits(w, update_index, update_index);
+	for (i = 0; i < N; i++) {
+		uint8_t hash[GIT_SHA256_RAWSZ] = { 0 };
+		char name[100];
+		int n;
+
+		set_test_hash(hash, i);
+
+		snprintf(name, sizeof(name), "refs/heads/branch%02d", i);
+
+		ref.refname = name;
+		ref.update_index = update_index;
+		ref.value_type = REFTABLE_REF_VAL1;
+		ref.value.val1 = hash;
+		(*names)[i] = xstrdup(name);
+
+		n = reftable_writer_add_ref(w, &ref);
+		EXPECT(n == 0);
+	}
+
+	for (i = 0; i < N; i++) {
+		uint8_t hash[GIT_SHA256_RAWSZ] = { 0 };
+		char name[100];
+		int n;
+
+		set_test_hash(hash, i);
+
+		snprintf(name, sizeof(name), "refs/heads/branch%02d", i);
+
+		log.refname = name;
+		log.update_index = update_index;
+		log.value_type = REFTABLE_LOG_UPDATE;
+		log.value.update.new_hash = hash;
+		log.value.update.message = "message";
+
+		n = reftable_writer_add_log(w, &log);
+		EXPECT(n == 0);
+	}
+
+	n = reftable_writer_close(w);
+	EXPECT(n == 0);
+
+	stats = writer_stats(w);
+	for (i = 0; i < stats->ref_stats.blocks; i++) {
+		int off = i * opts.block_size;
+		if (off == 0) {
+			off = header_size(
+				(hash_id == GIT_SHA256_FORMAT_ID) ? 2 : 1);
+		}
+		EXPECT(buf->buf[off] == 'r');
+	}
+
+	EXPECT(stats->log_stats.blocks > 0);
+	reftable_writer_free(w);
+}
+
+static void test_log_buffer_size(void)
+{
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_write_options opts = {
+		.block_size = 4096,
+	};
+	int err;
+	int i;
+	struct reftable_log_record
+		log = { .refname = "refs/heads/master",
+			.update_index = 0xa,
+			.value_type = REFTABLE_LOG_UPDATE,
+			.value = { .update = {
+					   .name = "Han-Wen Nienhuys",
+					   .email = "hanwen@google.com",
+					   .tz_offset = 100,
+					   .time = 0x5e430672,
+					   .message = "commit: 9\n",
+				   } } };
+	struct reftable_writer *w =
+		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+
+	/* This tests buffer extension for log compression. Must use a random
+	   hash, to ensure that the compressed part is larger than the original.
+	*/
+	uint8_t hash1[GIT_SHA1_RAWSZ], hash2[GIT_SHA1_RAWSZ];
+	for (i = 0; i < GIT_SHA1_RAWSZ; i++) {
+		hash1[i] = (uint8_t)(rand() % 256);
+		hash2[i] = (uint8_t)(rand() % 256);
+	}
+	log.value.update.old_hash = hash1;
+	log.value.update.new_hash = hash2;
+	reftable_writer_set_limits(w, update_index, update_index);
+	err = reftable_writer_add_log(w, &log);
+	EXPECT_ERR(err);
+	err = reftable_writer_close(w);
+	EXPECT_ERR(err);
+	reftable_writer_free(w);
+	strbuf_release(&buf);
+}
+
+static void test_log_write_read(void)
+{
+	int N = 2;
+	char **names = reftable_calloc(sizeof(char *) * (N + 1));
+	int err;
+	struct reftable_write_options opts = {
+		.block_size = 256,
+	};
+	struct reftable_ref_record ref = { NULL };
+	int i = 0;
+	struct reftable_log_record log = { NULL };
+	int n;
+	struct reftable_iterator it = { NULL };
+	struct reftable_reader rd = { NULL };
+	struct reftable_block_source source = { NULL };
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_writer *w =
+		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+	const struct reftable_stats *stats = NULL;
+	reftable_writer_set_limits(w, 0, N);
+	for (i = 0; i < N; i++) {
+		char name[256];
+		struct reftable_ref_record ref = { NULL };
+		snprintf(name, sizeof(name), "b%02d%0*d", i, 130, 7);
+		names[i] = xstrdup(name);
+		ref.refname = name;
+		ref.update_index = i;
+
+		err = reftable_writer_add_ref(w, &ref);
+		EXPECT_ERR(err);
+	}
+	for (i = 0; i < N; i++) {
+		uint8_t hash1[GIT_SHA1_RAWSZ], hash2[GIT_SHA1_RAWSZ];
+		struct reftable_log_record log = { NULL };
+		set_test_hash(hash1, i);
+		set_test_hash(hash2, i + 1);
+
+		log.refname = names[i];
+		log.update_index = i;
+		log.value_type = REFTABLE_LOG_UPDATE;
+		log.value.update.old_hash = hash1;
+		log.value.update.new_hash = hash2;
+
+		err = reftable_writer_add_log(w, &log);
+		EXPECT_ERR(err);
+	}
+
+	n = reftable_writer_close(w);
+	EXPECT(n == 0);
+
+	stats = writer_stats(w);
+	EXPECT(stats->log_stats.blocks > 0);
+	reftable_writer_free(w);
+	w = NULL;
+
+	block_source_from_strbuf(&source, &buf);
+
+	err = init_reader(&rd, &source, "file.log");
+	EXPECT_ERR(err);
+
+	err = reftable_reader_seek_ref(&rd, &it, names[N - 1]);
+	EXPECT_ERR(err);
+
+	err = reftable_iterator_next_ref(&it, &ref);
+	EXPECT_ERR(err);
+
+	/* end of iteration. */
+	err = reftable_iterator_next_ref(&it, &ref);
+	EXPECT(0 < err);
+
+	reftable_iterator_destroy(&it);
+	reftable_ref_record_release(&ref);
+
+	err = reftable_reader_seek_log(&rd, &it, "");
+	EXPECT_ERR(err);
+
+	i = 0;
+	while (1) {
+		int err = reftable_iterator_next_log(&it, &log);
+		if (err > 0) {
+			break;
+		}
+
+		EXPECT_ERR(err);
+		EXPECT_STREQ(names[i], log.refname);
+		EXPECT(i == log.update_index);
+		i++;
+		reftable_log_record_release(&log);
+	}
+
+	EXPECT(i == N);
+	reftable_iterator_destroy(&it);
+
+	/* cleanup. */
+	strbuf_release(&buf);
+	free_names(names);
+	reader_close(&rd);
+}
+
+static void test_table_read_write_sequential(void)
+{
+	char **names;
+	struct strbuf buf = STRBUF_INIT;
+	int N = 50;
+	struct reftable_iterator it = { NULL };
+	struct reftable_block_source source = { NULL };
+	struct reftable_reader rd = { NULL };
+	int err = 0;
+	int j = 0;
+
+	write_table(&names, &buf, N, 256, GIT_SHA1_FORMAT_ID);
+
+	block_source_from_strbuf(&source, &buf);
+
+	err = init_reader(&rd, &source, "file.ref");
+	EXPECT_ERR(err);
+
+	err = reftable_reader_seek_ref(&rd, &it, "");
+	EXPECT_ERR(err);
+
+	while (1) {
+		struct reftable_ref_record ref = { NULL };
+		int r = reftable_iterator_next_ref(&it, &ref);
+		EXPECT(r >= 0);
+		if (r > 0) {
+			break;
+		}
+		EXPECT(0 == strcmp(names[j], ref.refname));
+		EXPECT(update_index == ref.update_index);
+
+		j++;
+		reftable_ref_record_release(&ref);
+	}
+	EXPECT(j == N);
+	reftable_iterator_destroy(&it);
+	strbuf_release(&buf);
+	free_names(names);
+
+	reader_close(&rd);
+}
+
+static void test_table_write_small_table(void)
+{
+	char **names;
+	struct strbuf buf = STRBUF_INIT;
+	int N = 1;
+	write_table(&names, &buf, N, 4096, GIT_SHA1_FORMAT_ID);
+	EXPECT(buf.len < 200);
+	strbuf_release(&buf);
+	free_names(names);
+}
+
+static void test_table_read_api(void)
+{
+	char **names;
+	struct strbuf buf = STRBUF_INIT;
+	int N = 50;
+	struct reftable_reader rd = { NULL };
+	struct reftable_block_source source = { NULL };
+	int err;
+	int i;
+	struct reftable_log_record log = { NULL };
+	struct reftable_iterator it = { NULL };
+
+	write_table(&names, &buf, N, 256, GIT_SHA1_FORMAT_ID);
+
+	block_source_from_strbuf(&source, &buf);
+
+	err = init_reader(&rd, &source, "file.ref");
+	EXPECT_ERR(err);
+
+	err = reftable_reader_seek_ref(&rd, &it, names[0]);
+	EXPECT_ERR(err);
+
+	err = reftable_iterator_next_log(&it, &log);
+	EXPECT(err == REFTABLE_API_ERROR);
+
+	strbuf_release(&buf);
+	for (i = 0; i < N; i++) {
+		reftable_free(names[i]);
+	}
+	reftable_iterator_destroy(&it);
+	reftable_free(names);
+	reader_close(&rd);
+	strbuf_release(&buf);
+}
+
+static void test_table_read_write_seek(int index, int hash_id)
+{
+	char **names;
+	struct strbuf buf = STRBUF_INIT;
+	int N = 50;
+	struct reftable_reader rd = { NULL };
+	struct reftable_block_source source = { NULL };
+	int err;
+	int i = 0;
+
+	struct reftable_iterator it = { NULL };
+	struct strbuf pastLast = STRBUF_INIT;
+	struct reftable_ref_record ref = { NULL };
+
+	write_table(&names, &buf, N, 256, hash_id);
+
+	block_source_from_strbuf(&source, &buf);
+
+	err = init_reader(&rd, &source, "file.ref");
+	EXPECT_ERR(err);
+	EXPECT(hash_id == reftable_reader_hash_id(&rd));
+
+	if (!index) {
+		rd.ref_offsets.index_offset = 0;
+	} else {
+		EXPECT(rd.ref_offsets.index_offset > 0);
+	}
+
+	for (i = 1; i < N; i++) {
+		int err = reftable_reader_seek_ref(&rd, &it, names[i]);
+		EXPECT_ERR(err);
+		err = reftable_iterator_next_ref(&it, &ref);
+		EXPECT_ERR(err);
+		EXPECT(0 == strcmp(names[i], ref.refname));
+		EXPECT(REFTABLE_REF_VAL1 == ref.value_type);
+		EXPECT(i == ref.value.val1[0]);
+
+		reftable_ref_record_release(&ref);
+		reftable_iterator_destroy(&it);
+	}
+
+	strbuf_addstr(&pastLast, names[N - 1]);
+	strbuf_addstr(&pastLast, "/");
+
+	err = reftable_reader_seek_ref(&rd, &it, pastLast.buf);
+	if (err == 0) {
+		struct reftable_ref_record ref = { NULL };
+		int err = reftable_iterator_next_ref(&it, &ref);
+		EXPECT(err > 0);
+	} else {
+		EXPECT(err > 0);
+	}
+
+	strbuf_release(&pastLast);
+	reftable_iterator_destroy(&it);
+
+	strbuf_release(&buf);
+	for (i = 0; i < N; i++) {
+		reftable_free(names[i]);
+	}
+	reftable_free(names);
+	reader_close(&rd);
+}
+
+static void test_table_read_write_seek_linear(void)
+{
+	test_table_read_write_seek(0, GIT_SHA1_FORMAT_ID);
+}
+
+static void test_table_read_write_seek_linear_sha256(void)
+{
+	test_table_read_write_seek(0, GIT_SHA256_FORMAT_ID);
+}
+
+static void test_table_read_write_seek_index(void)
+{
+	test_table_read_write_seek(1, GIT_SHA1_FORMAT_ID);
+}
+
+static void test_table_refs_for(int indexed)
+{
+	int N = 50;
+	char **want_names = reftable_calloc(sizeof(char *) * (N + 1));
+	int want_names_len = 0;
+	uint8_t want_hash[GIT_SHA1_RAWSZ];
+
+	struct reftable_write_options opts = {
+		.block_size = 256,
+	};
+	struct reftable_ref_record ref = { NULL };
+	int i = 0;
+	int n;
+	int err;
+	struct reftable_reader rd;
+	struct reftable_block_source source = { NULL };
+
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_writer *w =
+		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+
+	struct reftable_iterator it = { NULL };
+	int j;
+
+	set_test_hash(want_hash, 4);
+
+	for (i = 0; i < N; i++) {
+		uint8_t hash[GIT_SHA1_RAWSZ];
+		char fill[51] = { 0 };
+		char name[100];
+		uint8_t hash1[GIT_SHA1_RAWSZ];
+		uint8_t hash2[GIT_SHA1_RAWSZ];
+		struct reftable_ref_record ref = { NULL };
+
+		memset(hash, i, sizeof(hash));
+		memset(fill, 'x', 50);
+		/* Put the variable part in the start */
+		snprintf(name, sizeof(name), "br%02d%s", i, fill);
+		name[40] = 0;
+		ref.refname = name;
+
+		set_test_hash(hash1, i / 4);
+		set_test_hash(hash2, 3 + i / 4);
+		ref.value_type = REFTABLE_REF_VAL2;
+		ref.value.val2.value = hash1;
+		ref.value.val2.target_value = hash2;
+
+		/* 80 bytes / entry, so 3 entries per block. Yields 17
+		 */
+		/* blocks. */
+		n = reftable_writer_add_ref(w, &ref);
+		EXPECT(n == 0);
+
+		if (!memcmp(hash1, want_hash, GIT_SHA1_RAWSZ) ||
+		    !memcmp(hash2, want_hash, GIT_SHA1_RAWSZ)) {
+			want_names[want_names_len++] = xstrdup(name);
+		}
+	}
+
+	n = reftable_writer_close(w);
+	EXPECT(n == 0);
+
+	reftable_writer_free(w);
+	w = NULL;
+
+	block_source_from_strbuf(&source, &buf);
+
+	err = init_reader(&rd, &source, "file.ref");
+	EXPECT_ERR(err);
+	if (!indexed) {
+		rd.obj_offsets.is_present = 0;
+	}
+
+	err = reftable_reader_seek_ref(&rd, &it, "");
+	EXPECT_ERR(err);
+	reftable_iterator_destroy(&it);
+
+	err = reftable_reader_refs_for(&rd, &it, want_hash);
+	EXPECT_ERR(err);
+
+	j = 0;
+	while (1) {
+		int err = reftable_iterator_next_ref(&it, &ref);
+		EXPECT(err >= 0);
+		if (err > 0) {
+			break;
+		}
+
+		EXPECT(j < want_names_len);
+		EXPECT(0 == strcmp(ref.refname, want_names[j]));
+		j++;
+		reftable_ref_record_release(&ref);
+	}
+	EXPECT(j == want_names_len);
+
+	strbuf_release(&buf);
+	free_names(want_names);
+	reftable_iterator_destroy(&it);
+	reader_close(&rd);
+}
+
+static void test_table_refs_for_no_index(void)
+{
+	test_table_refs_for(0);
+}
+
+static void test_table_refs_for_obj_index(void)
+{
+	test_table_refs_for(1);
+}
+
+static void test_write_empty_table(void)
+{
+	struct reftable_write_options opts = { 0 };
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_writer *w =
+		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+	struct reftable_block_source source = { NULL };
+	struct reftable_reader *rd = NULL;
+	struct reftable_ref_record rec = { NULL };
+	struct reftable_iterator it = { NULL };
+	int err;
+
+	reftable_writer_set_limits(w, 1, 1);
+
+	err = reftable_writer_close(w);
+	EXPECT(err == REFTABLE_EMPTY_TABLE_ERROR);
+	reftable_writer_free(w);
+
+	EXPECT(buf.len == header_size(1) + footer_size(1));
+
+	block_source_from_strbuf(&source, &buf);
+
+	err = reftable_new_reader(&rd, &source, "filename");
+	EXPECT_ERR(err);
+
+	err = reftable_reader_seek_ref(rd, &it, "");
+	EXPECT_ERR(err);
+
+	err = reftable_iterator_next_ref(&it, &rec);
+	EXPECT(err > 0);
+
+	reftable_iterator_destroy(&it);
+	reftable_reader_free(rd);
+	strbuf_release(&buf);
+}
+
+static void test_write_key_order(void)
+{
+	struct reftable_write_options opts = { 0 };
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_writer *w =
+		reftable_new_writer(&strbuf_add_void, &buf, &opts);
+	struct reftable_ref_record refs[2] = {
+		{
+			.refname = "b",
+			.update_index = 1,
+			.value_type = REFTABLE_REF_SYMREF,
+			.value = {
+				.symref = "target",
+			},
+		}, {
+			.refname = "a",
+			.update_index = 1,
+			.value_type = REFTABLE_REF_SYMREF,
+			.value = {
+				.symref = "target",
+			},
+		}
+	};
+	int err;
+
+	reftable_writer_set_limits(w, 1, 1);
+	err = reftable_writer_add_ref(w, &refs[0]);
+	EXPECT_ERR(err);
+	err = reftable_writer_add_ref(w, &refs[1]);
+	printf("%d\n", err);
+	EXPECT(err == REFTABLE_API_ERROR);
+	reftable_writer_close(w);
+	reftable_writer_free(w);
+	strbuf_release(&buf);
+}
+
+static void test_corrupt_table_empty(void)
+{
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_block_source source = { NULL };
+	struct reftable_reader rd = { NULL };
+	int err;
+
+	block_source_from_strbuf(&source, &buf);
+	err = init_reader(&rd, &source, "file.log");
+	EXPECT(err == REFTABLE_FORMAT_ERROR);
+}
+
+static void test_corrupt_table(void)
+{
+	uint8_t zeros[1024] = { 0 };
+	struct strbuf buf = STRBUF_INIT;
+	struct reftable_block_source source = { NULL };
+	struct reftable_reader rd = { NULL };
+	int err;
+	strbuf_add(&buf, zeros, sizeof(zeros));
+
+	block_source_from_strbuf(&source, &buf);
+	err = init_reader(&rd, &source, "file.log");
+	EXPECT(err == REFTABLE_FORMAT_ERROR);
+	strbuf_release(&buf);
+}
+
+int readwrite_test_main(int argc, const char *argv[])
+{
+	RUN_TEST(test_corrupt_table);
+	RUN_TEST(test_corrupt_table_empty);
+	RUN_TEST(test_log_write_read);
+	RUN_TEST(test_write_key_order);
+	RUN_TEST(test_table_read_write_seek_linear_sha256);
+	RUN_TEST(test_log_buffer_size);
+	RUN_TEST(test_table_write_small_table);
+	RUN_TEST(test_buffer);
+	RUN_TEST(test_table_read_api);
+	RUN_TEST(test_table_read_write_sequential);
+	RUN_TEST(test_table_read_write_seek_linear);
+	RUN_TEST(test_table_read_write_seek_index);
+	RUN_TEST(test_table_refs_for_no_index);
+	RUN_TEST(test_table_refs_for_obj_index);
+	RUN_TEST(test_write_empty_table);
+	return 0;
+}
diff --git a/reftable/reftable-tests.h b/reftable/reftable-tests.h
index 5e7698ae654..3d541fa5c0c 100644
--- a/reftable/reftable-tests.h
+++ b/reftable/reftable-tests.h
@@ -14,7 +14,7 @@ int block_test_main(int argc, const char **argv);
 int merged_test_main(int argc, const char **argv);
 int record_test_main(int argc, const char **argv);
 int refname_test_main(int argc, const char **argv);
-int reftable_test_main(int argc, const char **argv);
+int readwrite_test_main(int argc, const char **argv);
 int stack_test_main(int argc, const char **argv);
 int tree_test_main(int argc, const char **argv);
 int reftable_dump_main(int argc, char *const *argv);
diff --git a/t/helper/test-reftable.c b/t/helper/test-reftable.c
index 050551fa698..898aba836fd 100644
--- a/t/helper/test-reftable.c
+++ b/t/helper/test-reftable.c
@@ -6,6 +6,7 @@ int cmd__reftable(int argc, const char **argv)
 	basics_test_main(argc, argv);
 	block_test_main(argc, argv);
 	record_test_main(argc, argv);
+	readwrite_test_main(argc, argv);
 	tree_test_main(argc, argv);
 	return 0;
 }
