function LocationChangeListener(browser) {
  this.browser = browser;
  browser.addProgressListener(this, Ci.nsIWebProgress.NOTIFY_LOCATION);
}

LocationChangeListener.prototype = {
  wasSynthetic: false,
  browser: null,

  destroy() {
    this.browser.removeProgressListener(this);
  },

  onLocationChange(webProgress, request, location, flags) {
    this.wasSynthetic = this.browser.isSyntheticDocument;
  },

  QueryInterface: ChromeUtils.generateQI([
    "nsIWebProgressListener",
    "nsISupportsWeakReference",
  ]),
};

const FILES = gTestPath
  .replace("browser_isSynthetic.js", "")
  .replace("chrome://mochitests/content/", "http://example.com/");

function waitForPageShow(browser) {
  return BrowserTestUtils.waitForContentEvent(browser, "pageshow", true);
}

add_task(async function () {
  let tab = BrowserTestUtils.addTab(gBrowser, "about:blank");
  let browser = tab.linkedBrowser;
  await BrowserTestUtils.browserLoaded(browser);
  let listener = new LocationChangeListener(browser);

  is(browser.isSyntheticDocument, false, "Should not be synthetic");

  let loadPromise = waitForPageShow(browser);
  BrowserTestUtils.loadURIString(
    browser,
    "data:text/html;charset=utf-8,<html/>"
  );
  await loadPromise;
  is(listener.wasSynthetic, false, "Should not be synthetic");
  is(browser.isSyntheticDocument, false, "Should not be synthetic");

  loadPromise = waitForPageShow(browser);
  BrowserTestUtils.loadURIString(browser, FILES + "empty.png");
  await loadPromise;
  is(listener.wasSynthetic, true, "Should be synthetic");
  is(browser.isSyntheticDocument, true, "Should be synthetic");

  loadPromise = waitForPageShow(browser);
  browser.goBack();
  await loadPromise;
  is(listener.wasSynthetic, false, "Should not be synthetic");
  is(browser.isSyntheticDocument, false, "Should not be synthetic");

  loadPromise = waitForPageShow(browser);
  browser.goForward();
  await loadPromise;
  is(listener.wasSynthetic, true, "Should be synthetic");
  is(browser.isSyntheticDocument, true, "Should be synthetic");

  listener.destroy();
  gBrowser.removeTab(tab);
});