single_download_late_used_preload.html

<!DOCTYPE html>
<script src="../resources/testharness.js"></script>
<script src="../resources/testharnessreport.js"></script>
<script>
    var t = async_test('Makes sure that preloaded resources are not downloaded again when used');
</script>
<div id=result></div>
<link rel=preload href="../resources/square.png" as=image>
<script>
    window.addEventListener("load", t.step_func(function() {
        setTimeout(t.step_func(function() {
            document.getElementById("result").innerHTML = "<image src='../resources/square.png'>";
            setTimeout(t.step_func(function() {
                assert_equals(performance.getEntriesByType("resource").length, 3);
                t.done();
            }), 400);
        }), 400);
    }));
</script>

chromium/third_party/blink/web_tests/http/tests/preload/single_download_late_used_preload.html