1 files changed, 46 insertions, 0 deletions
diff --git a/accessible/tests/browser/events/browser_alert.js b/accessible/tests/browser/events/browser_alert.js
new file mode 100644
index 0000000000..f35a602fa3
--- /dev/null
+++ b/accessible/tests/browser/events/browser_alert.js
@@ -0,0 +1,46 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test that alert events aren't fired when reflow happens but no actual
+ * insertion occurs.
+ */
+addAccessibleTask(
+  `
+<div id="alert" role="alert">
+  <div id="content" hidden>content</div>
+</div>
+  `,
+  async function (browser, docAcc) {
+    const alert = findAccessibleChildByID(docAcc, "alert");
+    info("Showing content");
+    await contentSpawnMutation(
+      browser,
+      { expected: [[EVENT_ALERT, alert]] },
+      () => {
+        content.document.getElementById("content").hidden = false;
+      }
+    );
+    info("Changing content display style and removing text");
+    const content = findAccessibleChildByID(docAcc, "content");
+    await contentSpawnMutation(
+      browser,
+      {
+        expected: [[EVENT_REORDER, content]],
+        unexpected: [[EVENT_ALERT, alert]],
+      },
+      () => {
+        const node = content.document.getElementById("content");
+        node.textContent = "";
+        // This causes the node's layout frame to be reconstructed. This in
+        // turn causes a11y to queue it as an insertion in case there were
+        // changes. Because it already has an Accessible, This node is skipped
+        // when processing insertions, so we should not fire an alert event.
+        node.style.display = "flex";
+      }
+    );
+  },
+  { chrome: true, topLevel: true, remoteIframe: true }
+);