Move tests into a separate directory

Also run these tests on Github Actions as part of the PR request
flow.

tun/tests/packets.rs

@@ -0,0 +1,36 @@
+use fehler::throws;
+use std::io::Error;
+use std::io::Write;
+use std::net::Ipv4Addr;
+use tun::TunInterface;
+
+#[throws]
+#[test]
+#[ignore = "requires interactivity"]
+#[cfg(not(target_os = "windows"))]
+fn tst_read() {
+    // This test is interactive, you need to send a packet to any server through 192.168.1.10
+    // EG. `sudo route add 8.8.8.8 192.168.1.10`,
+    //`dig @8.8.8.8 hackclub.com`
+    let mut tun = TunInterface::new()?;
+    println!("tun name: {:?}", tun.name()?);
+    tun.set_ipv4_addr(Ipv4Addr::from([192, 168, 1, 10]))?;
+    println!("tun ip: {:?}", tun.ipv4_addr()?);
+    println!("Waiting for a packet...");
+    let buf = &mut [0u8; 1500];
+    let res = tun.read(buf);
+    println!("Received!");
+    assert!(res.is_ok());
+}
+
+#[test]
+#[throws]
+#[ignore = "requires interactivity"]
+#[cfg(not(target_os = "windows"))]
+fn write_packets() {
+    let mut tun = TunInterface::new()?;
+    let mut buf = [0u8; 1500];
+    buf[0] = 6 << 4;
+    let bytes_written = tun.write(&buf)?;
+    assert_eq!(bytes_written, 1504);
+}