Support ---test-cynthion --save-captures option.

src/main.rs

@@ -47,9 +47,14 @@ use ui::{
     stop_cynthion
 };
 
+fn have_argument(name: &str) -> bool {
+    std::env::args().any(|arg| arg == name)
+}
+
 fn main() {
-    if std::env::args().any(|arg| arg == "--test-cynthion") {
-        test_cynthion::run_test();
+    if have_argument("--test-cynthion") {
+        let save_captures = have_argument("--save-captures");
+        test_cynthion::run_test(save_captures);
     } else {
         let application = gtk::Application::new(
             Some("com.greatscottgadgets.packetry"),

src/test_cynthion.rs

@@ -8,25 +8,29 @@ use crate::capture::{
     PacketId,
 };
 use crate::decoder::Decoder;
+use crate::pcap::Writer;
 
 use anyhow::{Context, Error};
 use futures_lite::future::block_on;
 use nusb::transfer::RequestBuffer;
 
+use std::path::PathBuf;
 use std::thread::sleep;
 use std::time::Duration;
 
-pub fn run_test() {
-    for (speed, ep_addr, length, sof) in [
-        (Speed::High, 0x81, 4096, Some((124500,  125500, 500))),
-        (Speed::Full, 0x82,  512, Some((995000, 1005000,  50))),
-        (Speed::Low,  0x83,   64, None)]
+pub fn run_test(save_captures: bool) {
+    for (name, speed, ep_addr, length, sof) in [
+        ("HS", Speed::High, 0x81, 4096, Some((124500,  125500, 500))),
+        ("FS", Speed::Full, 0x82,  512, Some((995000, 1005000,  50))),
+        ("LS", Speed::Low,  0x83,   64, None)]
     {
-        test(speed, ep_addr, length, sof).unwrap();
+        test(save_captures, name, speed, ep_addr, length, sof).unwrap();
     }
 }
 
-fn test(speed: Speed,
+fn test(save_capture: bool,
+        name: &str,
+        speed: Speed,
         ep_addr: u8,
         length: usize,
         sof: Option<(u64, u64, u64)>)
@@ -96,6 +100,19 @@ fn test(speed: Speed,
             .context("Error decoding packet")?;
     }
 
+    if save_capture {
+        // Write the capture to a file.
+        let path = PathBuf::from(format!("./HITL-{name}.pcap"));
+        let mut writer = Writer::open(path)?;
+        for i in 0..reader.packet_index.len() {
+            let packet_id = PacketId::from(i);
+            let packet = reader.packet(packet_id)?;
+            let timestamp_ns = reader.packet_time(packet_id)?;
+            writer.add_packet(&packet, timestamp_ns)?;
+        }
+        writer.close()?;
+    }
+
     // Look for the test device in the capture.
     let device_id = DeviceId::from(1);
     let device_data = reader.device_data(&device_id)?;