diff --git a/test/reader/reader2.c b/test/reader/reader2.c
index 4e7e7d2c0..03d34a92e 100644
--- a/test/reader/reader2.c
+++ b/test/reader/reader2.c
@@ -61,9 +61,7 @@ test_iter_next(void *data, size_t desired_size) {
 	(void)desired_size;
 	if (iter->remaining == 0) {
 		iter->data = "";
-	}
-	if (iter->remaining == 0) {
-		return -1;
+		return 0;
 	}
 	iter->remaining--;
 	iter->size = strlen(iter->data);
@@ -304,6 +302,219 @@ test_reader2_advance_with_zero_size() {
 	sqsh__reader2_cleanup(&reader);
 }
 
+static void
+test_reader2_advance_once(void) {
+	int rv;
+	struct SqshReader2 reader = {0};
+	struct TestIterator iter = {
+			.data = "THIS IS A TEST STRING", .remaining = 1};
+
+	rv = sqsh__reader2_init(&reader, &test_iter, &iter);
+	assert(rv == 0);
+
+	rv = sqsh__reader2_advance(&reader, 0, 6);
+	assert(rv == 0);
+
+	const uint8_t *data = sqsh__reader2_data(&reader);
+	assert(data == (void *)iter.data);
+
+	sqsh__reader2_cleanup(&reader);
+}
+
+static void
+test_reader2_advance_once_with_offset(void) {
+	int rv;
+	struct SqshReader2 reader = {0};
+	struct TestIterator iter = {
+			.data = "THIS IS A TEST STRING", .remaining = 1};
+	rv = sqsh__reader2_init(&reader, &test_iter, &iter);
+	assert(rv == 0);
+
+	rv = sqsh__reader2_advance(&reader, 4, 6);
+	assert(rv == 0);
+
+	const uint8_t *data = sqsh__reader2_data(&reader);
+	assert(data == (uint8_t *)&iter.data[4]);
+
+	sqsh__reader2_cleanup(&reader);
+}
+
+static void
+test_reader2_advance_twice_with_offset(void) {
+	int rv;
+	struct SqshReader2 reader = {0};
+	struct TestIterator iter = {
+			.data = "THIS IS A TEST STRING", .remaining = 1};
+
+	rv = sqsh__reader2_init(&reader, &test_iter, &iter);
+	assert(rv == 0);
+
+	rv = sqsh__reader2_advance(&reader, 4, 6);
+	assert(rv == 0);
+
+	const uint8_t *data = sqsh__reader2_data(&reader);
+	assert(data == (uint8_t *)&iter.data[4]);
+
+	rv = sqsh__reader2_advance(&reader, 6, 2);
+	assert(rv == 0);
+
+	const uint8_t *data2 = sqsh__reader2_data(&reader);
+	assert(data2 == (uint8_t *)&iter.data[10]);
+
+	sqsh__reader2_cleanup(&reader);
+}
+
+static void
+test_reader2_initial_advance(void) {
+	int rv;
+	struct SqshReader2 reader = {0};
+	struct TestIterator iter = {
+			.data = "THIS IS A TEST STRING", .remaining = 1};
+	rv = sqsh__reader2_init(&reader, &test_iter, &iter);
+	assert(rv == 0);
+
+	rv = sqsh__reader2_advance(&reader, 5, 3);
+	assert(rv == 0);
+	const uint8_t *data = sqsh__reader2_data(&reader);
+	assert(3 == sqsh__reader2_size(&reader));
+	assert(memcmp(data, "IS ", 3) == 0);
+	assert(data == (uint8_t *)&iter.data[5]);
+
+	sqsh__reader2_cleanup(&reader);
+}
+
+static void
+test_reader2_advance_to_out_of_bounds(void) {
+	int rv;
+	struct SqshReader2 reader = {0};
+	struct TestIterator iter = {
+			.data = "THIS IS A TEST STRING", .remaining = 1};
+
+	rv = sqsh__reader2_init(&reader, &test_iter, &iter);
+	assert(rv == 0);
+
+	rv = sqsh__reader2_advance(&reader, strlen(iter.data), 1);
+	assert(rv < 0);
+
+	sqsh__reader2_cleanup(&reader);
+}
+
+static void
+test_reader2_advance_over_boundary(void) {
+	int rv;
+	struct SqshReader2 reader = {0};
+	struct TestIterator iter = {.data = "0123456789", .remaining = 2};
+
+	rv = sqsh__reader2_init(&reader, &test_iter, &iter);
+	assert(rv == 0);
+
+	rv = sqsh__reader2_advance(&reader, 9, 2);
+	assert(rv == 0);
+	const uint8_t *data = sqsh__reader2_data(&reader);
+	assert(2 == sqsh__reader2_size(&reader));
+	assert(memcmp(data, "90", 2) == 0);
+
+	sqsh__reader2_cleanup(&reader);
+}
+
+static void
+test_reader2_initial_advance_2(void) {
+	int rv;
+	struct SqshReader2 reader = {0};
+	struct TestIterator iter = {.data = "ABCD", .remaining = 10};
+
+	rv = sqsh__reader2_init(&reader, &test_iter, &iter);
+	assert(rv == 0);
+
+	rv = sqsh__reader2_advance(&reader, 7, 5);
+	assert(rv == 0);
+
+	const uint8_t *data = sqsh__reader2_data(&reader);
+	assert(sqsh__reader2_size(&reader) == 5);
+	assert(memcmp(data, "DABCD", 5) == 0);
+
+	sqsh__reader2_cleanup(&reader);
+}
+
+static void
+test_reader2_error_1(void) {
+	int rv;
+	struct SqshReader2 reader = {0};
+	struct TestIterator iter = {.data = "AB", .remaining = 10};
+
+	rv = sqsh__reader2_init(&reader, &test_iter, &iter);
+	assert(rv == 0);
+
+	rv = sqsh__reader2_advance(&reader, 0, 4);
+	assert(rv == 0);
+
+	const uint8_t *data = sqsh__reader2_data(&reader);
+	assert(sqsh__reader2_size(&reader) == 4);
+	assert(memcmp(data, "ABAB", 4) == 0);
+
+	iter.data = "12";
+	rv = sqsh__reader2_advance(&reader, 4, 4);
+	assert(rv == 0);
+
+	data = sqsh__reader2_data(&reader);
+	assert(sqsh__reader2_size(&reader) == 4);
+	assert(memcmp(data, "1212", 4) == 0);
+
+	sqsh__reader2_cleanup(&reader);
+}
+
+static void
+test_reader2_map_into_buffer(void) {
+	int rv;
+	struct SqshReader2 reader = {0};
+	struct TestIterator iter = {.data = "0123456789", .remaining = 2};
+
+	rv = sqsh__reader2_init(&reader, &test_iter, &iter);
+	assert(rv == 0);
+
+	rv = sqsh__reader2_advance(&reader, 8, 4);
+	assert(rv == 0);
+
+	const uint8_t *data = sqsh__reader2_data(&reader);
+	assert(sqsh__reader2_size(&reader) == 4);
+	assert(memcmp(data, "8901", 4) == 0);
+
+	rv = sqsh__reader2_advance(&reader, 1, 4);
+	assert(rv == 0);
+
+	data = sqsh__reader2_data(&reader);
+	assert(sqsh__reader2_size(&reader) == 4);
+	assert(memcmp(data, "9012", 4) == 0);
+
+	sqsh__reader2_cleanup(&reader);
+}
+
+static void
+test_reader2_map_into_buffer_twice(void) {
+	int rv;
+	struct SqshReader2 reader = {0};
+	struct TestIterator iter = {.data = "0123456789", .remaining = 3};
+
+	rv = sqsh__reader2_init(&reader, &test_iter, &iter);
+	assert(rv == 0);
+
+	rv = sqsh__reader2_advance(&reader, 8, 4);
+	assert(rv == 0);
+
+	const uint8_t *data = sqsh__reader2_data(&reader);
+	assert(sqsh__reader2_size(&reader) == 4);
+	assert(memcmp(data, "8901", 4) == 0);
+
+	rv = sqsh__reader2_advance(&reader, 1, 14);
+	assert(rv == 0);
+
+	data = sqsh__reader2_data(&reader);
+	assert(sqsh__reader2_size(&reader) == 14);
+	assert(memcmp(data, "90123456789012", 14) == 0);
+
+	sqsh__reader2_cleanup(&reader);
+}
+
 DECLARE_TESTS
 TEST(test_reader2_init)
 TEST(test_reader2_advance_to_block)
@@ -315,4 +526,14 @@ TEST(test_reader2_from_buffered_to_buffered)
 TEST(test_reader2_from_buffered_to_buffered)
 TEST(test_reader2_advance_inside_buffered)
 TEST(test_reader2_advance_with_zero_size)
+TEST(test_reader2_advance_once)
+TEST(test_reader2_advance_once_with_offset)
+TEST(test_reader2_advance_twice_with_offset)
+TEST(test_reader2_initial_advance)
+TEST(test_reader2_advance_to_out_of_bounds)
+TEST(test_reader2_advance_over_boundary)
+TEST(test_reader2_initial_advance_2)
+TEST(test_reader2_error_1)
+TEST(test_reader2_map_into_buffer)
+TEST(test_reader2_map_into_buffer_twice)
 END_TESTS