assertThrows(IOException.class, () -> Transport.readn(is, new byte[5], 0, 10));
        }

        @Test
        @DisplayName("readn should return 0 when no more bytes available")
        void shouldReturnZeroWhenStreamEmpty() throws IOException {
            InputStream is = new ByteArrayInputStream("Hi".getBytes());
            byte[] buffer = new byte[10];

            Transport.readn(is, buffer, 0, 2); // Read all