Bug 1699619 - [devtools] Wait for a11y panel initialization in browser_aboutdebugging_devtoolstoolbox_reload r=ochameau

Differential Revision: https://phabricator.services.mozilla.com/D110345

devtools/client/aboutdebugging/test/browser/browser_aboutdebugging_devtoolstoolbox_reload.js

@@ -61,12 +61,25 @@ async function testReloadAboutDevToolsToolbox(toolId) {
   const toolbox = getToolbox(devtoolsWindow);
   await toolbox.selectTool(toolId);
 
+  // The a11y panel finishes its initialization after selectTool resolves.
+  // TODO: The a11y panel init should only resolve when the UI is ready and all
+  // initial requests are completed. See Bug 1702078.
+  if (toolId === "accessibility") {
+    await waitForA11yPanel(toolbox);
+  }
+
   info("Wait for requests to settle before reloading");
   await toolbox.target.client.waitForRequestsToSettle();
 
   info("Reload about:devtools-toolbox page");
   devtoolsBrowser.reload();
-  await gDevTools.once("toolbox-ready");
+  const newToolbox = await gDevTools.once("toolbox-ready");
+
+  // Again, wait for the delayed a11y panel initialization.
+  if (toolId === "accessibility") {
+    await waitForA11yPanel(newToolbox);
+  }
+
   ok(true, "Toolbox is re-created again");
 
   // Check that about:devtools-toolbox is still selected tab. See Bug 1570692.
@@ -85,3 +98,8 @@ async function testReloadAboutDevToolsToolbox(toolId) {
   await closeAboutDevtoolsToolbox(document, devtoolsTab, window);
   await removeTab(tab);
 }
+
+async function waitForA11yPanel(toolbox) {
+  const panel = toolbox.getPanel("accessibility");
+  await panel._accessibilityViewInitialized;
+}

devtools/client/accessibility/panel.js

@@ -103,6 +103,8 @@ AccessibilityPanel.prototype = {
       EVENTS.ACCESSIBILITY_INSPECTOR_UPDATED,
       this.onAccessibilityInspectorUpdated
     );
+    // Expose a promise so that tests can wait for the UI to be ready.
+    this._accessibilityViewInitialized = this.panelWin.once(EVENTS.INITIALIZED);
 
     this.shouldRefresh = true;