1 files changed, 49 insertions, 0 deletions
diff --git a/toolkit/components/thumbnails/test/browser_thumbnails_bg_queueing.js b/toolkit/components/thumbnails/test/browser_thumbnails_bg_queueing.js
new file mode 100644
index 0000000000..92e8711637
--- /dev/null
+++ b/toolkit/components/thumbnails/test/browser_thumbnails_bg_queueing.js
@@ -0,0 +1,49 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+add_task(async function thumbnails_bg_queueing() {
+  let urls = [
+    "https://www.example.com/0",
+    "https://www.example.com/1",
+    // an item that will timeout to ensure timeouts work and we resume.
+    bgTestPageURL({ wait: 2002 }),
+    "https://www.example.com/2",
+  ];
+  dontExpireThumbnailURLs(urls);
+
+  let promises = [];
+
+  for (let url of urls) {
+    ok(!thumbnailExists(url), "Thumbnail should not exist yet: " + url);
+    let isTimeoutTest = url.includes("wait");
+
+    let promise = bgCapture(url, {
+      timeout: isTimeoutTest ? 100 : 30000,
+      onDone: capturedURL => {
+        ok(!!urls.length, "onDone called, so URLs should still remain");
+        is(
+          capturedURL,
+          urls.shift(),
+          "Captured URL should be currently expected URL (i.e., " +
+            "capture() callbacks should be called in the correct order)"
+        );
+        if (isTimeoutTest) {
+          ok(
+            !thumbnailExists(capturedURL),
+            "Thumbnail shouldn't exist for timed out capture"
+          );
+        } else {
+          ok(
+            thumbnailExists(capturedURL),
+            "Thumbnail should be cached after capture"
+          );
+          removeThumbnail(url);
+        }
+      },
+    });
+
+    promises.push(promise);
+  }
+
+  await Promise.all(promises);
+});