/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */


var cs = Cc["@mozilla.org/consoleservice;1"].
  getService(Ci.nsIConsoleService);
var ps = Cc["@mozilla.org/preferences-service;1"].
  getService(Ci.nsIPrefService);

function makeBuffer(length) {
  return new Array(length + 1).join('x');
}

/**
 * @resolves |true| if execution proceeded without warning,
 * |false| if there was a warning.
 */
function checkWarning(pref, buffer) {
  return new Promise(resolve => {
    let complete = false;
    let listener = {
      observe: function(event) {
        let message = event.message;
        if (!(message.startsWith("Warning: attempting to write")
              && message.includes(pref))) {
          return;
        }
        if (complete) {
          return;
        }
        complete = true;
        do_print("Warning while setting " + pref);
        cs.unregisterListener(listener);
        resolve(true);
      }
    };
    do_timeout(1000, function() {
      if (complete) {
        return;
      }
      complete = true;
      do_print("No warning while setting " + pref);
      cs.unregisterListener(listener);
      resolve(false);
    });
    cs.registerListener(listener);
    ps.setCharPref(pref, buffer);
  });
}

function run_test() {
  run_next_test();
}

add_task(async function() {
  // Simple change, shouldn't cause a warning
  do_print("Checking that a simple change doesn't cause a warning");
  let buf = makeBuffer(100);
  let warned = await checkWarning("string.accept", buf);
  do_check_false(warned);

  // Large change, should cause a warning
  do_print("Checking that a large change causes a warning");
  buf = makeBuffer(32 * 1024);
  warned = await checkWarning("string.warn", buf);
  do_check_true(warned);
});
