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Test Info: Warnings

  • This test gets skipped with pattern: serviceworker_e10s
<!DOCTYPE html>
<!-- The JS bytecode cache is not supposed to be observable. To make it
observable, the ScriptLoader is instrumented to trigger events on the
script tag. These events are followed to reconstruct the code path taken by
the script loader and associate a simple name which is checked in these
test cases.
<meta charset="utf-8">
<title>Test for saving and loading bytecode in/from the necko cache</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="utils.js"></script>
<script type="application/javascript">
// This is the state machine of the trace events produced by the
// ScriptLoader. This state machine is used to give a name to each
// code path, such that we can assert each code path with a single word.
var scriptLoaderStateMachine = {
"scriptloader_load_source": {
"scriptloader_execute": {
"scriptloader_encode": {
"scriptloader_bytecode_saved": "bytecode_saved",
"scriptloader_bytecode_failed": "bytecode_failed"
"scriptloader_no_encode": "source_exec"
"scriptloader_load_bytecode": {
"scriptloader_fallback": {
// Replicate the top-level state machine without
// "scriptloader_load_bytecode" transition.
"scriptloader_load_source": {
"scriptloader_execute": {
"scriptloader_encode": {
"scriptloader_bytecode_saved": "fallback_bytecode_saved",
"scriptloader_bytecode_failed": "fallback_bytecode_failed"
"scriptloader_no_encode": "fallback_source_exec"
"scriptloader_execute": "bytecode_exec"
var gScript = SpecialPowers.
function WaitForScriptTagEvent(url) {
var iframe = document.createElement("iframe");
var stateMachine = scriptLoaderStateMachine;
var stateHistory = [];
var stateMachineResolve, stateMachineReject;
var statePromise = new Promise((resolve, reject) => {
stateMachineResolve = resolve;
stateMachineReject = reject;
var ping = 0;
// Walk the script loader state machine with the emitted events.
function log_event(evt) {
// If we have multiple script tags in the loaded source, make sure
// we only watch a single one.
if ( != "watchme")
dump("## ScriptLoader event: " + evt.type + "\n");
if (typeof stateMachine == "object")
stateMachine = stateMachine[evt.type];
if (typeof stateMachine == "string") {
// We arrived to a final state, report the name of it.
var result = stateMachine;
if (ping) {
result = `${result} & ping(=${ping})`;
} else if (stateMachine === undefined) {
// We followed an unknown transition, report the known history.
var iwin = iframe.contentWindow;
iwin.addEventListener("scriptloader_load_source", log_event);
iwin.addEventListener("scriptloader_load_bytecode", log_event);
iwin.addEventListener("scriptloader_generate_bytecode", log_event);
iwin.addEventListener("scriptloader_execute", log_event);
iwin.addEventListener("scriptloader_encode", log_event);
iwin.addEventListener("scriptloader_no_encode", log_event);
iwin.addEventListener("scriptloader_bytecode_saved", log_event);
iwin.addEventListener("scriptloader_bytecode_failed", log_event);
iwin.addEventListener("scriptloader_fallback", log_event);
iwin.addEventListener("ping", (evt) => {
ping += 1;
dump(`## Content event: ${evt.type} (=${ping})\n`);
iframe.src = url;
statePromise.then(() => {
return statePromise;
promise_test(async function() {
// Setting dom.expose_test_interfaces pref causes the
// nsScriptLoadRequest to fire event on script tags, with information
// about its internal state. The ScriptLoader source send events to
// trace these and resolve a promise with the path taken by the
// script loader.
// Setting dom.script_loader.bytecode_cache.strategy to -1 causes the
// nsScriptLoadRequest to force all the conditions necessary to make a
// script be saved as bytecode in the alternate data storage provided
// by the channel (necko cache).
await SpecialPowers.pushPrefEnv({set: [
["dom.serviceWorkers.enabled", true],
["dom.serviceWorkers.testing.enabled", true],
['dom.script_loader.bytecode_cache.enabled', true],
['dom.expose_test_interfaces', true],
['dom.script_loader.bytecode_cache.strategy', -1]
// Register the service worker that perform the pass-through fetch.
var registration = await navigator.serviceWorker
.register("fetch.js", {scope: "./"});
let sw = registration.installing ||;
// wait for service worker be activated
await waitForState(sw, 'activated');
await testCheckTheJSBytecodeCache();
await testSavebytecodeAfterTheInitializationOfThePage();
await testDoNotSaveBytecodeOnCompilationErrors();
await registration.unregister();
await teardown();
function teardown() {
return new Promise((resolve, reject) => {
gScript.addMessageListener("teardown-complete", function teardownCompleteHandler() {
gScript.removeMessageListener("teardown-complete", teardownCompleteHandler);
async function testCheckTheJSBytecodeCache() {
dump("## Test: Check the JS bytecode cache\n");
// Load the test page, and verify that the code path taken by the
// nsScriptLoadRequest corresponds to the code path which is loading a
// source and saving it as bytecode.
var stateMachineResult = WaitForScriptTagEvent("file_js_cache.html");
assert_equals(await stateMachineResult, "bytecode_saved",
"[1] ScriptLoadRequest status after the first visit");
// Reload the same test page, and verify that the code path taken by
// the nsScriptLoadRequest corresponds to the code path which is
// loading bytecode and executing it.
stateMachineResult = WaitForScriptTagEvent("file_js_cache.html");
assert_equals(await stateMachineResult, "bytecode_exec",
"[2] ScriptLoadRequest status after the second visit");
// Load another page which loads the same script with an SRI, while
// the cached bytecode does not have any. This should fallback to
// loading the source before saving the bytecode once more.
stateMachineResult = WaitForScriptTagEvent("file_js_cache_with_sri.html");
assert_equals(await stateMachineResult, "fallback_bytecode_saved",
"[3] ScriptLoadRequest status after the SRI hash");
// Loading a page, which has the same SRI should verify the SRI and
// continue by executing the bytecode.
var stateMachineResult1 = WaitForScriptTagEvent("file_js_cache_with_sri.html");
// Loading a page which does not have a SRI while we have one in the
// cache should not change anything. We should also be able to load
// the cache simultanesouly.
var stateMachineResult2 = WaitForScriptTagEvent("file_js_cache.html");
assert_equals(await stateMachineResult1, "bytecode_exec",
"[4] ScriptLoadRequest status after same SRI hash");
assert_equals(await stateMachineResult2, "bytecode_exec",
"[5] ScriptLoadRequest status after visit with no SRI");
async function testSavebytecodeAfterTheInitializationOfThePage() {
dump("## Test: Save bytecode after the initialization of the page");
// The test page add a new script which generate a "ping" event, which
// should be recorded before the bytecode is stored in the cache.
var stateMachineResult =
assert_equals(await stateMachineResult, "bytecode_saved & ping(=3)",
"Wait on all scripts to be executed");
async function testDoNotSaveBytecodeOnCompilationErrors() {
dump("## Test: Do not save bytecode on compilation errors");
// The test page loads a script which contains a syntax error, we should
// not attempt to encode any bytecode for it.
var stateMachineResult =
assert_equals(await stateMachineResult, "source_exec",
"Check the lack of bytecode encoding");