test_image_cache_notification.html

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<!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>