Bug 1350064 - test that updated system add-ons are reset on app update r=aswan

MozReview-Commit-ID: BbUtIMfCDXZ

--HG--
extra : rebase_source : f8204c72b482f50d93c0f3e8878cc4fe83ec29a6

toolkit/mozapps/extensions/internal/XPIProvider.jsm

@@ -8660,15 +8660,21 @@ Object.assign(SystemAddonInstallLocation.prototype, {
    * Resets the add-on set so on the next startup the default set will be used.
    */
   resetAddonSet() {
+    logger.info("Removing all system add-on upgrades.");
 
+    // remove everything from the pref first, if uninstall
+    // fails then at least they will not be re-activated on
+    // next restart.
+    this._saveAddonSet({ schema: 1, addons: {} });
+
+    // If this is running at app startup, the pref being cleared
+    // will cause later stages of startup to notice that the
+    // old updates are now gone.
+    //
+    // Updates will only be explicitly uninstalled if they are
+    // removed restartlessly, for instance if they are no longer
+    // part of the latest update set.
     if (this._addonSet) {
-      logger.info("Removing all system add-on upgrades.");
-
-      // remove everything from the pref first, if uninstall
-      // fails then at least they will not be re-activated on
-      // next restart.
-      this._saveAddonSet({ schema: 1, addons: {} });
-
       for (let id of Object.keys(this._addonSet.addons)) {
         AddonManager.getAddonByID(id, addon => {
           if (addon) {

toolkit/mozapps/extensions/test/xpcshell/test_system_reset.js

@@ -359,6 +359,10 @@ add_task(function* test_bad_app_cert() {
   distroDir.leafName = "app3";
   startupManager();
 
+  // Since we updated the app version, the system addon set should be reset as well.
+  let addonSet = Services.prefs.getCharPref(PREF_SYSTEM_ADDON_SET);
+  do_check_eq(addonSet, `{"schema":1,"addons":{}}`);
+
   // Add-on will still be present
   let addon = yield promiseAddonByID("system1@tests.mozilla.org");
   do_check_neq(addon, null);
@@ -413,3 +417,4 @@ add_task(function* test_updated() {
 
   yield promiseShutdownManager();
 });
+