Add test for writing to multiple offsets

References #1098.

test/integration-test-main.sh

@@ -650,6 +650,12 @@ function test_open_second_fd {
     rm_test_file second_fd_file
 }
 
+function test_write_multiple_offsets {
+    describe "test writing to multiple offsets"
+    ../../write_multiple_offsets.py ${TEST_TEXT_FILE}
+    rm_test_file
+}
+
 function add_all_tests {
     add_tests test_append_file 
     add_tests test_truncate_file 
@@ -681,6 +687,7 @@ function add_all_tests {
     add_tests test_concurrency
     add_tests test_concurrent_writes
     add_tests test_open_second_fd
+    add_tests test_write_multiple_offsets
 }
 
 init_suite

test/write_multiple_offsets.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+
+import os
+import sys
+
+filename = sys.argv[1]
+data = bytes('a', 'utf-8')
+
+fd = os.open(filename, os.O_CREAT | os.O_TRUNC | os.O_WRONLY)
+try:
+    os.pwrite(fd, data, 1024)
+    os.pwrite(fd, data, 16 * 1024 * 1024)
+    os.pwrite(fd, data, 18 * 1024 * 1024)
+finally:
+    os.close(fd)
+
+stat = os.lstat(filename)
+assert stat.st_size == 18 * 1024 * 1024 + 1