test/ls: add test for locale-aware quoting

tests/by-util/test_ls.rs

@@ -2690,6 +2690,71 @@ mod quoting {
             &[],
         );
     }
+
+    #[cfg(not(any(target_vendor = "apple", target_os = "windows", target_os = "openbsd")))]
+    #[test]
+    /// This test creates files with an UTF-8 encoded name and verify that it
+    /// gets escaped depending on the used locale.
+    fn test_locale_aware_quoting() {
+        let cases: &[(&[u8], _, _, &[&str])] = &[
+            (
+                "😁".as_bytes(),               // == b"\xF0\x9F\x98\x81"
+                "''$'\\360\\237\\230\\201'\n", // ASCII sees 4 bytes
+                "😁\n",                        // UTF-8 sees an emoji
+                &["--quoting-style=shell-escape"],
+            ),
+            (
+                "€".as_bytes(),           // == b"\xE2\x82\xAC"
+                "''$'\\342\\202\\254'\n", // ASCII sees 3 bytes
+                "€\n",                    // UTF-8 still only 2
+                &["--quoting-style=shell-escape"],
+            ),
+            (
+                b"\xC2\x80\xC2\x81", // 2 first Unicode control characters
+                "????\n",            // ASCII sees 4 bytes
+                "??\n",              // UTF-8 sees only 2
+                &["--quoting-style=literal", "--hide-control-char"],
+            ),
+            (
+                b"\xC2\xC2\x81",
+                "???\n", // ASCII sees 3 bytes
+                "??\n",  // UTF-8 still only 2
+                &["--quoting-style=literal", "--hide-control-char"],
+            ),
+            (
+                b"\xC2\x81\xC2",
+                "???\n", // ASCII sees 3 bytes
+                "??\n",  // UTF-8 still only 2
+                &["--quoting-style=literal", "--hide-control-char"],
+            ),
+        ];
+
+        for (filename, ascii_ref, utf_8_ref, args) in cases {
+            let scene = TestScenario::new(util_name!());
+            let at = &scene.fixtures;
+
+            let filename = uucore::os_str_from_bytes(filename)
+                .expect("Filename is valid Unicode supported on Linux");
+
+            at.touch(filename);
+
+            // When the locale does not handle UTF-8 encoding, escaping is done.
+            scene
+                .ucmd()
+                .env("LC_ALL", "C") // Non UTF-8 locale
+                .args(args)
+                .succeeds()
+                .stdout_only(ascii_ref);
+
+            // When the locale has UTF-8 support, the symbol is shown as-is.
+            scene
+                .ucmd()
+                .env("LC_ALL", "en_US.UTF-8") // UTF-8 locale
+                .args(args)
+                .succeeds()
+                .stdout_only(utf_8_ref);
+        }
+    }
 }
 
 #[test]