gecko/browser/components/sessionstore/test/browser_history_cap.js

/* Any copyright is dedicated to the Public Domain.
 * http://creativecommons.org/publicdomain/zero/1.0/ */

"use strict";

/**
 * This test ensures that the preferences (added in bug 943339) that control how
 * many back and forward button session history entries we store work correctly.
 *
 * It adds a number of entries to the session history, restores them and checks
 * that the restored state matches the preferences.
 */

add_task(function *test_history_cap() {
  const baseURL = "http://example.com/browser_history_cap#"
  const maxEntries  = 9; // The number of generated session history entries.
  const middleEntry = 4; // The zero-based index of the middle entry.

  const maxBack1 = 2; // The history cap settings used for the first test,
  const maxFwd1 = 3;  // where maxBack1 + 1 + maxFwd1 < maxEntries.

  const maxBack2 = 5; // The history cap settings used for the other tests, 
  const maxFwd2 = 5;  // where maxBack2 + 1 + maxFwd2 > maxEntries.

  // Set the relevant preferences for the first test.
  gPrefService.setIntPref("browser.sessionhistory.max_entries", maxEntries);
  gPrefService.setIntPref("browser.sessionstore.max_serialize_back", maxBack1);
  gPrefService.setIntPref("browser.sessionstore.max_serialize_forward", maxFwd1);

  // Make sure the settings we modify are reset afterward.
  registerCleanupFunction(() => {
    gPrefService.clearUserPref("browser.sessionhistory.max_entries");
    gPrefService.clearUserPref("browser.sessionstore.max_serialize_back");
    gPrefService.clearUserPref("browser.sessionstore.max_serialize_forward");
  });

  let tab = gBrowser.addTab();
  let browser = tab.linkedBrowser;
  yield promiseBrowserLoaded(browser);

  // Generate the tab state entries and set the one-based
  // tab-state index to the middle session history entry.
  let tabState = {entries: [], index: middleEntry + 1};
  for (let i = 0; i < maxEntries; i++) {
    tabState.entries.push({url: baseURL + i});
  }

  info("Testing situation where only a subset of session history entries should be restored.");

  ss.setTabState(tab, JSON.stringify(tabState));
  yield promiseTabRestored(tab);
  SyncHandlers.get(tab.linkedBrowser).flush();

  let restoredTabState = JSON.parse(ss.getTabState(tab));
  is(restoredTabState.entries.length, maxBack1 + 1 + maxFwd1,
    "The expected number of session history entries was restored.");
  is(restoredTabState.index, maxBack1 + 1, "The restored tab-state index is correct");

  let indexURLOffset = middleEntry - (restoredTabState.index - 1);
  for (let i = 0; i < restoredTabState.entries.length; i++) {
    is(restoredTabState.entries[i].url, baseURL + (i + indexURLOffset),
        "URL of restored entry matches the expected URL.");
  }

  // Set the relevant preferences for the other tests.
  gPrefService.setIntPref("browser.sessionstore.max_serialize_back", maxBack2);
  gPrefService.setIntPref("browser.sessionstore.max_serialize_forward", maxFwd2);

  info("Testing situation where all of the entries in the session history should be restored.");

  ss.setTabState(tab, JSON.stringify(tabState));
  yield promiseTabRestored(tab);
  SyncHandlers.get(tab.linkedBrowser).flush();

  restoredTabState = JSON.parse(ss.getTabState(tab));
  is(restoredTabState.entries.length, maxEntries,
    "The expected number of session history entries was restored.");
  is(restoredTabState.index, middleEntry + 1, "The restored tab-state index is correct");

  for (let i = middleEntry - 2; i <= middleEntry + 2; i++) {
    is(restoredTabState.entries[i].url, baseURL + i,
        "URL of restored entry matches the expected URL.");
  }

  info("Testing situation where only the 1 + maxFwd2 oldest entries should be restored.");

  // Set the one-based tab-state index to the oldest session history entry.
  tabState.index = 1;

  ss.setTabState(tab, JSON.stringify(tabState));
  yield promiseTabRestored(tab);
  SyncHandlers.get(tab.linkedBrowser).flush();

  restoredTabState = JSON.parse(ss.getTabState(tab));
  is(restoredTabState.entries.length, 1 + maxFwd2,
    "The expected number of session history entries was restored.");
  is(restoredTabState.index, 1, "The restored tab-state index is correct");

  for (let i = 0; i <= 2; i++) {
    is(restoredTabState.entries[i].url, baseURL + i,
        "URL of restored entry matches the expected URL.");
  }

  info("Testing situation where only the maxBack2 + 1 newest entries should be restored.");

  // Set the one-based tab-state index to the newest session history entry.
  tabState.index = maxEntries;

  ss.setTabState(tab, JSON.stringify(tabState));
  yield promiseTabRestored(tab);
  SyncHandlers.get(tab.linkedBrowser).flush();

  restoredTabState = JSON.parse(ss.getTabState(tab));
  is(restoredTabState.entries.length, maxBack2 + 1,
    "The expected number of session history entries was restored.");
  is(restoredTabState.index, maxBack2 + 1, "The restored tab-state index is correct");

  indexURLOffset = (maxEntries - 1) - maxBack2;
  for (let i = maxBack2 - 2; i <= maxBack2; i++) {
    is(restoredTabState.entries[i].url, baseURL + (i + indexURLOffset),
        "URL of restored entry matches the expected URL.");
  }

  gBrowser.removeTab(tab);
});