tests/ls: test for sort by width option

tests/by-util/test_ls.rs

@@ -1564,6 +1564,25 @@ fn test_ls_sort_name() {
         .stdout_is(".a\n.b\na\nb\n");
 }
 
+#[test]
+fn test_ls_sort_width() {
+    let scene = TestScenario::new(util_name!());
+    let at = &scene.fixtures;
+
+    at.touch("aaaaa");
+    at.touch("bbb");
+    at.touch("cccc");
+    at.touch("d");
+    at.touch("zz");
+
+    scene
+        .ucmd()
+        .arg("--sort=width")
+        .succeeds()
+        .stdout_is("d\nzz\nbbb\ncccc\naaaaa\n");
+
+}
+
 #[test]
 fn test_ls_order_size() {
     let scene = TestScenario::new(util_name!());