static void ctxTestIO(S input, S regexp) {
  ctxTestIO("", input, regexp);
}

static void ctxTestIO(S prelude, S input, S regexp) {
  S desc = prelude + input + " -> " + regexp;
  regexp = ctxREToJavaRE(trim(multiSpacesToSingle(regexp)));
  print("\nTesting: " + desc);
  try {
    ctxContext().rulesFired.clear();
    ctxClearOutput();
    ctxProcessInput(input);
    ctxProcessRules();
    ctxDefaultOnEmptyOutput();
    S output = ctxDropEmotions(ctxGetOutput());
    bool ok = regexpIC(regexp, output).find();
    desc += " | " + struct(output) + " " + sfu(ctxContext().rulesFired);
    addTestResultVerbose(desc, ok);
  } catch e {
    addTestResult(desc, e);
  }
}

Began life as a copy of #1008973