bug(wc): Add a test for unexpected behavior (#1723)

tests/by-util/test_wc.rs

@@ -8,6 +8,17 @@ fn test_stdin_default() {
         .stdout_is("  13 109 772\n");
 }
 
+#[test]
+fn test_utf8() {
+    new_ucmd!()
+        .args(&["-lwmcL"])
+        .pipe_in_fixture("UTF_8_test.txt")
+        .run()
+        .stdout_is(" 0 0 0 0 0\n");
+    // GNU returns "  300  2086 22219 22781    79"
+    // TODO: we should fix that to match GNU's behavior
+}
+
 #[test]
 fn test_stdin_line_len_regression() {
     new_ucmd!()