Bug 1494549 - Wait until ADB started in USB status sidebar test;r=daisuke

Depends on D8335

Differential Revision: https://phabricator.services.mozilla.com/D8513

--HG--
extra : moz-landing-system : lando

devtools/client/aboutdebugging-new/test/browser/browser_aboutdebugging_sidebar_usb_status.js

@@ -4,6 +4,7 @@
 "use strict";
 
 const { adbAddon } = require("devtools/shared/adb/adb-addon");
+const { ADB } = require("devtools/shared/adb/adb");
 
 /**
  * This test asserts that the sidebar shows a message describing the status of the USB
@@ -35,6 +36,13 @@ add_task(async function() {
   adbAddon.install();
   await waitUntil(() => usbStatusElement.textContent.includes("USB devices enabled"));
 
+  // Right now we are resuming as soon as "USB devices enabled" is displayed, but ADB
+  // might still be starting up. If we move to uninstall directly, the ADB startup will
+  // fail and we will have an unhandled promise rejection.
+  // See Bug 1498469.
+  info("Wait until ADB has started.");
+  await waitUntil(() => ADB.ready);
+
   info("Uninstall the adb extension and wait for the message to udpate");
   adbAddon.uninstall();
   await waitUntil(() => usbStatusElement.textContent.includes("USB devices disabled"));