serialPort_loopback_BreakError-manual.https.html

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  <head>

    <meta charset="utf-8">

    <title></title>

    <script src="/resources/testharness.js"></script>

    <script src="/resources/testharnessreport.js"></script>

    <script src="resources/common.js"></script>

    <script src="resources/manual.js"></script>

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  <body>

<p>

      These tests require a connected serial device configured to act as a

      "loopback" device, with the transmit and receive pins wired together.

    </p>

    <script>

      manual_serial_test(async (t, port) => {

        await port.open({baudRate: 115200, bufferSize: 1024});

        let reader = port.readable.getReader();

        let readPromise = (async () => {

          // A single zero byte will be read before the break is detected.

          const {value, done} = await reader.read();

          compareArrays(value, new Uint8Array([0]));

          assert_false(done);

          try {

            const {value, done} = await reader.read();

            assert_unreached(`Expected break, got ${value.byteLength} bytes`);

          } catch (e) {

            assert_equals(e.constructor, DOMException);

            assert_equals(e.name, 'BreakError');

        })();

        await port.setSignals({break: true});

        await readPromise;

        await port.setSignals({break: false});

        const writer = port.writable.getWriter();

        // |data| is small enough to be completely transmitted.

        let data = new Uint8Array([1, 2, 3, 4, 5, 6, 7, 8]);

        await writer.write(data);

        writer.releaseLock();

        reader = port.readable.getReader();

        const buffer = await readWithLength(reader, data.byteLength);;

        compareArrays(buffer, data);

        reader.releaseLock();

        await port.close();

      }, 'Break is detected.');

    </script>

  </body>

</html>