fix: SymbolicArgs::from_str with group ids

src/fs/permission.rs

@@ -216,10 +216,12 @@ impl FromStr for SymbolicArgs {
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         match Modes::<SymbolicMode>::from_str(s) {
-            Ok(perms) => Ok(Self::Mode(perms)),
-            Err(_) => match Modes::<GroupId>::from_str(s) {
-                Ok(perms) => Ok(Self::Group(perms)),
-                Err(_) => Err(FromStrError::new(format!("{} is not a valid argument", s)).into()),
+            Ok(perms) if perms.0.bits() > 0 => Ok(Self::Mode(perms)),
+            Ok(_) | Err(_) => match Modes::<GroupId>::from_str(s) {
+                Ok(perms) if perms.0.bits() > 0 => Ok(Self::Group(perms)),
+                Ok(_) | Err(_) => {
+                    Err(FromStrError::new(format!("{} is not a valid argument", s)).into())
+                }
             },
         }
     }
@@ -413,7 +415,7 @@ impl Display for Permissions {
 
 #[cfg(test)]
 mod tests {
-    use std::str::FromStr;
+    use std::{fmt::Debug, str::FromStr};
 
     use enumflags2::BitFlags;
 
@@ -429,6 +431,41 @@ mod tests {
         assert_eq!(flags.to_string(), "7777");
     }
 
+    fn test_chars<T>(values: &[&str])
+    where
+        T: FromStr + ToString + Debug,
+        <T as FromStr>::Err: Debug,
+    {
+        let modes: Vec<(usize, T)> = values
+            .into_iter()
+            .map(|s| T::from_str(*s))
+            .map(Result::unwrap)
+            .enumerate()
+            .collect();
+
+        for (i, mode) in modes {
+            assert_eq!(values[i], mode.to_string())
+        }
+    }
+
+    #[test]
+    fn symbolic_modes() {
+        test_chars::<SymbolicMode>(&["r", "w", "x", "X", "s", "t"]);
+    }
+
+    #[test]
+    fn symbolic_groups() {
+        test_chars::<GroupId>(&["u", "g", "o"]);
+    }
+
+    #[test]
+    fn symbolic_args() {
+        assert_eq!(
+            SymbolicArgs::from_str("u").unwrap(),
+            SymbolicArgs::Group(Modes(BitFlags::from(GroupId::User)))
+        );
+    }
+
     #[test]
     fn symbolic_permissions() {
         let sym = Permissions::from_str("ug+w").unwrap();