Fix fill fast path

src/fill.rs

@@ -39,8 +39,12 @@ where
 {
     let options = width_or_options.into();
 
-    if text.len() < options.width && !text.contains('\n') && options.initial_indent.is_empty() {
-        String::from(text.trim_end_matches(' '))
+    if text.len() < options.width
+        && options.tab_width <= 1
+        && !text.contains('\n')
+        && options.initial_indent.is_empty()
+    {
+        String::from(text.trim_end_matches(&[' ', '\t']))
     } else {
         fill_slow_path(text, options)
     }
@@ -215,6 +219,21 @@ mod tests {
         );
     }
 
+    #[test]
+    fn fill_tabs() {
+        let options = Options::new(10).tab_width(4);
+        assert_eq!(
+            fill("Hello\t there\t friends", options),
+            "Hello\nthere\nfriends"
+        );
+    }
+
+    #[test]
+    fn fill_tabs_prevent_fast_path() {
+        let options = Options::new(10).tab_width(4);
+        assert_eq!(fill("Hey\tworld", options), "Hey\nworld");
+    }
+
     #[test]
     fn break_words_line_breaks() {
         assert_eq!(fill("ab\ncdefghijkl", 5), "ab\ncdefg\nhijkl");