ladybird/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeThrough.html

<script src="../include.js"></script>
<script>
    const CHUNK1 =  "well,";
    const CHUNK2 =  "hello";
    const CHUNK3 =  "friends!";

    asyncTest((done) => {
        const transformStream = new TransformStream({
            transform(chunk, controller) {
                controller.enqueue(
                    new TextDecoder("utf-8")
                        .decode(chunk)
                        .toUpperCase()
                );
            }
        });

        const stream = new ReadableStream({
            start(controller) {
                pullCount = 0;
            },

            pull(controller) {
                const textEncoder = new TextEncoder();

                ++pullCount;

                if (pullCount == 1) {
                    controller.enqueue(textEncoder.encode(CHUNK1));
                } else if (pullCount == 2) {
                    controller.enqueue(textEncoder.encode(CHUNK2));
                } else if (pullCount == 3) {
                    controller.enqueue(textEncoder.encode(CHUNK3));
                } else {
                    controller.close();
                }
            },

            cancel() {},
        });

        const reader = transformStream.readable.getReader();
        reader.read().then(function processText(result) {
            if (result.done) {
                done();
                return;
            }

            println(result.value);
            reader.read().then(processText);
        });

        stream.pipeThrough(transformStream);
    });
</script>