Add test for Socket::passcred/set_passcred and fix formatting.

src/sys/unix.rs

@@ -172,15 +172,15 @@ pub(crate) use libc::SO_LINGER;
     target_os = "watchos",
 ))]
 pub(crate) use libc::SO_LINGER_SEC as SO_LINGER;
+#[cfg(target_os = "linux")]
+pub(crate) use libc::SO_PASSCRED;
 pub(crate) use libc::{
     ip_mreq as IpMreq, linger, IPPROTO_IP, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, IPV6_MULTICAST_IF,
     IPV6_MULTICAST_LOOP, IPV6_UNICAST_HOPS, IPV6_V6ONLY, IP_ADD_MEMBERSHIP, IP_DROP_MEMBERSHIP,
     IP_MULTICAST_IF, IP_MULTICAST_LOOP, IP_MULTICAST_TTL, IP_TTL, MSG_OOB, MSG_PEEK, SOL_SOCKET,
     SO_BROADCAST, SO_ERROR, SO_KEEPALIVE, SO_RCVBUF, SO_RCVTIMEO, SO_REUSEADDR, SO_SNDBUF,
     SO_SNDTIMEO, SO_TYPE, TCP_NODELAY,
 };
-#[cfg(target_os = "linux")]
-pub(crate) use libc::SO_PASSCRED;
 #[cfg(not(any(
     target_os = "dragonfly",
     target_os = "haiku",

tests/socket.rs

@@ -1680,3 +1680,19 @@ fn cookie() {
         Err(err) => panic!("Could not get socket cookie a second time, err: {err}"),
     }
 }
+
+#[cfg(all(unix, target_os = "linux"))]
+#[test]
+fn set_passcred() {
+    let socket = Socket::new(Domain::UNIX, Type::DGRAM, None).unwrap();
+    assert!(!socket.passcred().unwrap());
+
+    socket.set_passcred(true).unwrap();
+    assert!(socket.passcred().unwrap());
+
+    let socket = Socket::new(Domain::UNIX, Type::STREAM, None).unwrap();
+    assert!(!socket.passcred().unwrap());
+
+    socket.set_passcred(true).unwrap();
+    assert!(socket.passcred().unwrap());
+}