test: refactor error handling with ParseError enum

tests/by-util/test_test.rs

@@ -928,3 +928,16 @@ fn test_long_integer() {
         ])
         .fails();
 }
+
+#[test]
+fn test_missing_argument_after() {
+    let mut ucmd = new_ucmd!();
+
+    let result = ucmd.args(&["(", "foo"]).fails();
+    result.no_stdout();
+    assert_eq!(result.exit_status().code().unwrap(), 2);
+    assert_eq!(
+        result.stderr_str().trim(),
+        "test: missing argument after 'foo'"
+    );
+}