Merge pull request #3053 from snobee/stat-handle-negative-time

stat: allow formatting of negative numbers

src/uu/stat/src/stat.rs

@@ -193,11 +193,19 @@ impl ScanUtil for str {
 }
 
 pub fn group_num(s: &str) -> Cow<str> {
-    assert!(s.chars().all(char::is_numeric));
+    let is_negative = s.starts_with('-');
+    assert!(is_negative || s.chars().take(1).all(|c| c.is_digit(10)));
+    assert!(s.chars().skip(1).all(|c| c.is_digit(10)));
     if s.len() < 4 {
         return s.into();
     }
     let mut res = String::with_capacity((s.len() - 1) / 3);
+    let s = if is_negative {
+        res.push('-');
+        &s[1..]
+    } else {
+        s
+    };
     let mut alone = (s.len() - 1) % 3 + 1;
     res.push_str(&s[..alone]);
     while alone != s.len() {

tests/by-util/test_stat.rs

@@ -34,6 +34,8 @@ fn test_group_num() {
     assert_eq!("24", group_num("24"));
     assert_eq!("4", group_num("4"));
     assert_eq!("", group_num(""));
+    assert_eq!("-5", group_num("-5"));
+    assert_eq!("-1,234", group_num("-1234"));
 }
 
 #[test]