Service worker: self.serviceWorker (#17285)

* Tests for self.serviceWorker

* Don't need `self`

* Add read only test

* Adding comments & test the object doesn't change

* Swap order

Author: jakearchibald

service-workers/service-worker/global-serviceworker.https.any.js

@@ -0,0 +1,53 @@
+// META: title=serviceWorker on service worker global
+// META: global=!default,serviceworker
+
+test(() => {
+  assert_equals(registration.installing, null, 'registration.installing');
+  assert_equals(registration.waiting, null, 'registration.waiting');
+  assert_equals(registration.active, null, 'registration.active');
+  assert_true('serviceWorker' in self, 'self.serviceWorker exists');
+  assert_equals(serviceWorker.state, 'parsed', 'serviceWorker.state');
+  assert_readonly(self, 'serviceWorker', `self.serviceWorker is read only`);
+}, 'First run');
+
+// Cache this for later tests.
+const initialServiceWorker = self.serviceWorker;
+
+async_test((t) => {
+  assert_true('serviceWorker' in self, 'self.serviceWorker exists');
+  serviceWorker.postMessage({ messageTest: true });
+
+  // The rest of the rest runs once we receive the above message.
+  addEventListener('message', t.step_func((event) => {
+    // Ignore unrelated messages.
+    if (!event.data.messageTest) return;
+    assert_equals(event.source, serviceWorker, 'event.source');
+    t.done();
+  }));
+}, 'Can post message to self during startup');
+
+// The test is registered now so there isn't a race condition when collecting tests, but the asserts
+// don't happen until the 'install' event fires.
+async_test((t) => {
+  addEventListener('install', t.step_func_done(() => {
+    assert_true('serviceWorker' in self, 'self.serviceWorker exists');
+    assert_equals(serviceWorker, initialServiceWorker, `self.serviceWorker hasn't changed`);
+    assert_equals(registration.installing, serviceWorker, 'registration.installing');
+    assert_equals(registration.waiting, null, 'registration.waiting');
+    assert_equals(registration.active, null, 'registration.active');
+    assert_equals(serviceWorker.state, 'installing', 'serviceWorker.state');
+  }));
+}, 'During install');
+
+// The test is registered now so there isn't a race condition when collecting tests, but the asserts
+// don't happen until the 'activate' event fires.
+async_test((t) => {
+  addEventListener('activate', t.step_func_done(() => {
+    assert_true('serviceWorker' in self, 'self.serviceWorker exists');
+    assert_equals(serviceWorker, initialServiceWorker, `self.serviceWorker hasn't changed`);
+    assert_equals(registration.installing, null, 'registration.installing');
+    assert_equals(registration.waiting, null, 'registration.waiting');
+    assert_equals(registration.active, serviceWorker, 'registration.active');
+    assert_equals(serviceWorker.state, 'activating', 'serviceWorker.state');
+  }));
+}, 'During activate');