Initial project import

tools/v/vlib/os/file_buffering_test.v

@@ -0,0 +1,87 @@
+import os
+
+const tfolder = os.join_path(os.vtmp_dir(), 'os_file_buffering_tests')
+
+fn testsuite_begin() {
+	os.rmdir_all(tfolder) or {}
+	assert !os.is_dir(tfolder)
+	os.mkdir_all(tfolder)!
+	os.chdir(tfolder)!
+	assert os.is_dir(tfolder)
+}
+
+fn testsuite_end() {
+	os.rmdir_all(tfolder) or {}
+}
+
+fn test_set_buffer_line_buffered() {
+	dump(@LOCATION)
+	mut buf := []u8{len: 25}
+	dump(buf)
+	mut wfile := os.open_file('text.txt', 'wb', 0o666)!
+	wfile.set_buffer(mut buf, .line_buffered)
+	wfile.write_string('----------------------------------\n')!
+	for line in ['hello\n', 'world\n', 'hi\n'] {
+		wfile.write_string(line)!
+		wfile.flush()
+		dump(buf)
+		print(buf.bytestr())
+		// assert buf.bytestr().contains(line) // this works on GLIBC, but fails on MUSL.
+		unsafe { buf.reset() }
+	}
+	wfile.close()
+
+	content := os.read_lines('text.txt')!
+	dump(content)
+	assert content == ['----------------------------------', 'hello', 'world', 'hi']
+}
+
+fn test_set_buffer_fully_buffered() {
+	dump(@LOCATION)
+	mut buf := []u8{len: 30}
+	dump(buf)
+	mut wfile := os.open_file('text.txt', 'wb', 0o666)!
+	wfile.set_buffer(mut buf, .fully_buffered)
+	// Ubuntu GLIBC 2.31 seems to not use the buffer for the first write call, but it does write to the buffer first for the subsequent ones.
+	// MUSL (detecting the MUSL version is deliberately made hard by its authors, because of course it is :-( ...), will skip the first 8 bytes
+	// of the buffer, and write everything after those.
+	wfile.write_string('S')!
+	wfile.write_string('---\n')!
+	dump(buf)
+	for line in ['hello\n', 'world\n', 'hi\n'] {
+		wfile.write_string(line)!
+		dump(buf)
+		// print(buf.bytestr())
+	}
+	wfile.close()
+	dump(buf)
+	// assert buf.bytestr().starts_with('---\nhello\nworld\nhi\n') // works on GLIBC, fails on MUSL
+	assert buf.bytestr().contains('---\nhello\nworld\n')
+
+	content := os.read_lines('text.txt')!
+	dump(content)
+	assert content == ['S---', 'hello', 'world', 'hi']
+}
+
+fn test_set_unbuffered() {
+	dump(@LOCATION)
+	mut buf := []u8{len: 30}
+	dump(buf)
+	mut wfile := os.open_file('text.txt', 'wb', 0o666)!
+	wfile.set_buffer(mut buf, .not_buffered)
+	wfile.write_string('S')!
+	wfile.write_string('---\n')!
+	dump(buf)
+	for line in ['hello\n', 'world\n', 'hi\n'] {
+		wfile.write_string(line)!
+		dump(buf)
+		// print(buf.bytestr())
+	}
+	wfile.close()
+	// dump(buf.bytestr())
+	assert buf.all(it == 0)
+
+	content := os.read_lines('text.txt')!
+	dump(content)
+	assert content == ['S---', 'hello', 'world', 'hi']
+}