1 files changed, 84 insertions, 0 deletions
diff --git a/devtools/client/inspector/test/browser_inspector_startup.js b/devtools/client/inspector/test/browser_inspector_startup.js
new file mode 100644
index 0000000000..7953b5c473
--- /dev/null
+++ b/devtools/client/inspector/test/browser_inspector_startup.js
@@ -0,0 +1,84 @@
+/* Any copyright is dedicated to the Public Domain.
+ http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Tests that the inspector loads early without waiting for load events.
+
+const server = createTestHTTPServer();
+
+// Register a slow image handler so we can simulate a long time between
+// a reload and the load event firing.
+server.registerContentType("gif", "image/gif");
+function onPageResourceRequest() {
+  return new Promise(done => {
+    server.registerPathHandler("/slow.gif", function (metadata, response) {
+      info("Image has been requested");
+      response.processAsync();
+      done(response);
+    });
+  });
+}
+
+// Test page load events.
+const TEST_URL =
+  "data:text/html," +
+  "<!DOCTYPE html>" +
+  "<head><meta charset='utf-8' /></head>" +
+  "<body>" +
+  "<p>Page loading slowly</p>" +
+  "<img src='http://localhost:" +
+  server.identity.primaryPort +
+  "/slow.gif' />" +
+  "</body>" +
+  "</html>";
+
+add_task(async function () {
+  const { inspector, tab } = await openInspectorForURL("about:blank");
+
+  const domContentLoaded = waitForLinkedBrowserEvent(tab, "DOMContentLoaded");
+  const pageLoaded = waitForLinkedBrowserEvent(tab, "load");
+
+  const markupLoaded = inspector.once("markuploaded");
+  const onRequest = onPageResourceRequest();
+
+  info("Navigate to the slow loading page");
+  const target = inspector.toolbox.target;
+  await target.navigateTo({ url: TEST_URL });
+
+  info("Wait for request made to the image");
+  const response = await onRequest;
+
+  // The request made to the image shouldn't block the DOMContentLoaded event
+  info("Wait for DOMContentLoaded");
+  await domContentLoaded;
+
+  // Nor does it prevent the inspector from loading
+  info("Wait for markup-loaded");
+  await markupLoaded;
+
+  ok(inspector.markup, "There is a markup view");
+  is(inspector.markup._elt.children.length, 1, "The markup view is rendering");
+  is(
+    await contentReadyState(tab),
+    "interactive",
+    "Page is still loading but the inspector is ready"
+  );
+
+  // Ends page load by unblocking the image request
+  response.finish();
+
+  // We should then receive the page load event
+  info("Wait for load");
+  await pageLoaded;
+});
+
+function waitForLinkedBrowserEvent(tab, event) {
+  return BrowserTestUtils.waitForContentEvent(tab.linkedBrowser, event, true);
+}
+
+function contentReadyState(tab) {
+  return SpecialPowers.spawn(tab.linkedBrowser, [], function () {
+    return content.document.readyState;
+  });
+}