Add tests for multiple mode specifications

tests/by-util/test_mkfifo.rs

@@ -99,6 +99,8 @@ fn test_create_fifo_with_mode_and_umask() {
     test_fifo_creation("u-r,g-w,o+x", 0o022, "p-w-r--rwx"); // spell-checker:disable-line
     test_fifo_creation("a=rwx,o-w", 0o022, "prwxrwxr-x"); // spell-checker:disable-line
     test_fifo_creation("=rwx,o-w", 0o022, "prwxr-xr-x"); // spell-checker:disable-line
+    test_fifo_creation("ug+rw,o+r", 0o022, "prw-rw-rw-"); // spell-checker:disable-line
+    test_fifo_creation("u=rwx,g=rx,o=", 0o022, "prwxr-x---"); // spell-checker:disable-line
 }
 
 #[test]

tests/by-util/test_mknod.rs

@@ -154,6 +154,22 @@ fn test_mknod_mode_permissions() {
     }
 }
 
+#[test]
+fn test_mknod_mode_comma_separated() {
+    let ts = TestScenario::new(util_name!());
+    ts.ucmd()
+        .arg("-m")
+        .arg("u=rwx,g=rx,o=")
+        .arg("test_file")
+        .arg("p")
+        .succeeds();
+    assert!(ts.fixtures.is_fifo("test_file"));
+    assert_eq!(
+        ts.fixtures.metadata("test_file").permissions().mode() & 0o777,
+        0o750
+    );
+}
+
 #[test]
 #[cfg(feature = "feat_selinux")]
 fn test_mknod_selinux() {