<!DOCTYPE HTML>
<html>
  <head>
    <script src="/tests/SimpleTest/SimpleTest.js"></script>
  </head>
  <body>
    <button>Add Image</button>
    <script>
      /* Test to ensure http-on-image-cache-response should only be notified
       * once per image
       */

      SimpleTest.waitForExplicitFinish();
      async function addImage() {
        const newImage = document.createElement("img");

        const imageLoaded = new Promise((r) => {
          newImage.onload = r;
        });

        newImage.src = "./over.png";
        document.body.appendChild(newImage);
        return imageLoaded;
      }

      let imageCacheCallbackRunCount = 0;
      const cb = SpecialPowers.wrapCallback(() => {
        imageCacheCallbackRunCount += 1;
      });
      SpecialPowers.addObserver(cb, "http-on-image-cache-response");

      async function runTest() {
        await addImage();
        SimpleTest.ok(imageCacheCallbackRunCount == 0, "first load of over.png shouldn't be cached");
        await addImage();
        SimpleTest.ok(imageCacheCallbackRunCount == 1, "second load of over.png should be cached");
        await addImage();
        await addImage();
        await addImage();
        SimpleTest.ok(imageCacheCallbackRunCount == 1, "further loads of over.png shouldn't be notified");
        SimpleTest.finish();
      }

      runTest();
    </script>
  </body>
</html>
