"`--group` is useless without `--long`"

src/options.rs

@@ -281,6 +281,9 @@ impl View {
         else if matches.opt_present("tree") {
             Err(Misfire::Useless("tree", false, "long"))
         }
+        else if matches.opt_present("group") {
+            Err(Misfire::Useless("group", false, "long"))
+        }
         else if matches.opt_present("level") && !matches.opt_present("recurse") {
             Err(Misfire::Useless2("level", "recurse", "tree"))
         }
@@ -629,6 +632,12 @@ mod test {
         assert_eq!(opts.unwrap_err(), Misfire::Useless("header", false, "long"))
     }
 
+    #[test]
+    fn just_group() {
+        let opts = Options::getopts(&[ "--group".to_string() ]);
+        assert_eq!(opts.unwrap_err(), Misfire::Useless("group", false, "long"))
+    }
+
     #[test]
     fn just_inode() {
         let opts = Options::getopts(&[ "--inode".to_string() ]);