When running tests in builds with the update checker disabled, all browser tests now fail with: A promise chain failed to handle a rejection: Cc['@mozilla.org/updates/update-checker;1'] is undefined; can't access its "createInstance" property - stack: CheckBrowserNeedsUpdate@resource://activity-stream/lib/ASRouterTargeting.jsm:66:9 Browser code can't rely on the update check service always being present, since there are compile-time options to disable it.

Commit pushed to master at https://github.com/mozilla/activity-stream https://github.com/mozilla/activity-stream/commit/db2f232e9cf65384df7f2c97aafcfffbcd531106 Fix Bug 1502266 - Verify that Update Checker is available before creating an instance (#4532)