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// META: script=/resources/test-only-api.js
// META: script=/serial/resources/common.js
// META: script=resources/automation.js
function detachBuffer(buffer) {
const channel = new MessageChannel();
channel.port1.postMessage('', [buffer]);
}
serial_test(async (t, fake) => {
const {port, fakePort} = await getFakeSerialPort(fake);
await port.open({baudRate: 9600, bufferSize: 64});
const writer = port.writable.getWriter();
const data = new Uint8Array(64);
detachBuffer(data.buffer);
// Writing a detached buffer is equivalent to writing an empty buffer so this
// should trivially succeed.
await writer.write(data);
writer.releaseLock();
await port.close();
}, 'Writing a detached buffer is safe');
serial_test(async (t, fake) => {
const {port, fakePort} = await getFakeSerialPort(fake);
// Select a buffer size smaller than the amount of data transferred.
await port.open({baudRate: 9600, bufferSize: 64});
// Start writing a buffer much larger than bufferSize above so that it can't
// all be transfered in a single operation.
const writer = port.writable.getWriter();
const data = new Uint8Array(1024);
const promise = writer.write(data);
writer.releaseLock();
// Read half of the written data and then detach the buffer.
await fakePort.readable();
await fakePort.readWithLength(data.byteLength / 2);
detachBuffer(data.buffer);
// When the buffer is detached its length becomes zero and so the write should
// succeed but it is undefined how much data was written before that happened.
await promise;
await port.close();
}, 'Detaching a buffer while writing is safe');
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