sort: test punctuation-only differences are kept by -u under locale

tests/by-util/test_sort.rs

@@ -3025,22 +3025,46 @@ fn test_consistent_sorting_with_i18n_collate() {
 }
 
 #[test]
-fn test_sort_locale_punctuation_weights() {
-    // Test for issue #12542
-    let input = "file10\nfile-10\n";
-    let expected_output = "file-10\nfile10\n";
-
-    new_ucmd!()
-        .env("LC_ALL", "en_US.UTF-8")
-        .pipe_in(input)
-        .succeeds()
-        .stdout_is(expected_output);
+fn test_sort_locale_punctuation() {
+    // Punctuation gets a distinguishing collation weight, so lines differing
+    // only by punctuation sort in a stable order (issue #12542) and are never
+    // merged by -u. This holds across the plain, explicit-key and stable paths,
+    // and in both locales. The wildcard-domain case comes from dehydrated, which
+    // relied on -u keeping a `*.domain.com` alias distinct from the bare domain.
+    // (input, expected, [(locale, args)...])
+    let cases = [
+        (
+            "file10\nfile-10\n",
+            "file-10\nfile10\n",
+            &[("en_US.UTF-8", &[][..]), ("C", &[][..])][..],
+        ),
+        (
+            "EU\nE.U\nE-U\n",
+            "E-U\nE.U\nEU\n",
+            &[
+                ("en_US.UTF-8", &["-u"][..]),
+                ("C", &["-u"][..]),
+                ("en_US.UTF-8", &["-u", "-k1,1"][..]),
+                ("en_US.UTF-8", &["-s", "-k1,1"][..]),
+            ][..],
+        ),
+        (
+            "domain.com\n*.domain.com\ndomain.com\n",
+            "*.domain.com\ndomain.com\n",
+            &[("en_US.UTF-8", &["-u"][..]), ("C", &["-u"][..])][..],
+        ),
+    ];
 
-    new_ucmd!()
-        .env("LC_ALL", "C")
-        .pipe_in(input)
-        .succeeds()
-        .stdout_is(expected_output);
+    for (input, expected, runs) in cases {
+        for (locale, args) in runs {
+            new_ucmd!()
+                .env("LC_ALL", *locale)
+                .args(args)
+                .pipe_in(input)
+                .succeeds()
+                .stdout_is(expected);
+        }
+    }
 }
 
 /* spell-checker: enable */