Bug 1649493 - Fix intermittent failure in test_remove_profile_engine.js - ensure we correctly wait for the cache to save. r=daleharvey

Differential Revision: https://phabricator.services.mozilla.com/D82228

toolkit/components/search/tests/xpcshell/test_remove_profile_engine.js

@@ -1,6 +1,9 @@
 /* Any copyright is dedicated to the Public Domain.
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
+// This test is to ensure that we remove xml files from searchplugins/ in the
+// profile directory when a user removes the actual engine from their profile.
+
 add_task(async function run_test() {
   // Copy an engine to [profile]/searchplugin/
   let dir = do_get_profile().clone();
@@ -15,14 +18,16 @@ add_task(async function run_test() {
   Assert.ok(file.exists());
 
   await AddonTestUtils.promiseStartupManager();
+  let cacheWrittenPromise = promiseAfterCache();
   await Services.search.init();
+  await cacheWrittenPromise;
 
   // Install the same engine through a supported way.
   useHttpServer();
+  cacheWrittenPromise = promiseAfterCache();
   await addTestEngines([{ name: "basic", xmlFileName: "engine-override.xml" }]);
-  await promiseAfterCache();
+  await cacheWrittenPromise;
   let data = await promiseCacheData();
-
   // Put the filePath inside the cache file, to simulate what a pre-58 version
   // of Firefox would have done.
   for (let engine of data.engines) {
@@ -33,7 +38,9 @@ add_task(async function run_test() {
 
   await promiseSaveCacheData(data);
 
+  cacheWrittenPromise = promiseAfterCache();
   await asyncReInit();
+  await cacheWrittenPromise;
 
   // test the engine is loaded ok.
   let engine = Services.search.getEngineByName("basic");