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test/fixtures/wpt/streams/readable-byte-streams/bad-buffers-and-views.any.js

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+// META: global=window,worker,shadowrealm
+'use strict';
+
+promise_test(() => {
+  const stream = new ReadableStream({
+    start(c) {
+      c.close();
+    },
+    type: 'bytes'
+  });
+
+  const reader = stream.getReader({ mode: 'byob' });
+  const view = new Uint8Array([1, 2, 3]);
+  return reader.read(view).then(({ value, done }) => {
+    // Sanity checks
+    assert_true(value instanceof Uint8Array, 'The value read must be a Uint8Array');
+    assert_not_equals(value, view, 'The value read must not be the *same* Uint8Array');
+    assert_array_equals(value, [], 'The value read must be an empty Uint8Array, since the stream is closed');
+    assert_true(done, 'done must be true, since the stream is closed');
+
+    // The important assertions
+    assert_not_equals(value.buffer, view.buffer, 'a different ArrayBuffer must underlie the value');
+    assert_equals(view.buffer.byteLength, 0, 'the original buffer must be detached');
+  });
+}, 'ReadableStream with byte source: read()ing from a closed stream still transfers the buffer');
+
+promise_test(() => {
+  const stream = new ReadableStream({
+    start(c) {
+      c.enqueue(new Uint8Array([1, 2, 3]));
+    },
+    type: 'bytes'
+  });
+
+  const reader = stream.getReader({ mode: 'byob' });
+  const view = new Uint8Array([4, 5, 6]);
+  return reader.read(view).then(({ value, done }) => {
+    // Sanity checks
+    assert_true(value instanceof Uint8Array, 'The value read must be a Uint8Array');
+    assert_not_equals(value, view, 'The value read must not be the *same* Uint8Array');
+    assert_array_equals(value, [1, 2, 3], 'The value read must be the enqueued Uint8Array, not the original values');
+    assert_false(done, 'done must be false, since the stream is not closed');
+
+    // The important assertions
+    assert_not_equals(value.buffer, view.buffer, 'a different ArrayBuffer must underlie the value');
+    assert_equals(view.buffer.byteLength, 0, 'the original buffer must be detached');
+  });
+}, 'ReadableStream with byte source: read()ing from a stream with queued chunks still transfers the buffer');
+
+test(() => {
+  new ReadableStream({
+    start(c) {
+      const view = new Uint8Array([1, 2, 3]);
+      c.enqueue(view);
+      assert_throws_js(TypeError, () => c.enqueue(view));
+    },
+    type: 'bytes'
+  });
+}, 'ReadableStream with byte source: enqueuing an already-detached buffer throws');
+
+test(() => {
+  new ReadableStream({
+    start(c) {
+      const view = new Uint8Array([]);
+      assert_throws_js(TypeError, () => c.enqueue(view));
+    },
+    type: 'bytes'
+  });
+}, 'ReadableStream with byte source: enqueuing a zero-length buffer throws');
+
+test(() => {
+  new ReadableStream({
+    start(c) {
+      const view = new Uint8Array(new ArrayBuffer(10), 0, 0);
+      assert_throws_js(TypeError, () => c.enqueue(view));
+    },
+    type: 'bytes'
+  });
+}, 'ReadableStream with byte source: enqueuing a zero-length view on a non-zero-length buffer throws');
+
+promise_test(t => {
+  const stream = new ReadableStream({
+    start(c) {
+      c.enqueue(new Uint8Array([1, 2, 3]));
+    },
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  const view = new Uint8Array([4, 5, 6]);
+  return reader.read(view).then(() => {
+    // view is now detached
+    return promise_rejects_js(t, TypeError, reader.read(view));
+  });
+}, 'ReadableStream with byte source: reading into an already-detached buffer rejects');
+
+promise_test(t => {
+  const stream = new ReadableStream({
+    start(c) {
+      c.enqueue(new Uint8Array([1, 2, 3]));
+    },
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  const view = new Uint8Array();
+  return promise_rejects_js(t, TypeError, reader.read(view));
+}, 'ReadableStream with byte source: reading into a zero-length buffer rejects');
+
+promise_test(t => {
+  const stream = new ReadableStream({
+    start(c) {
+      c.enqueue(new Uint8Array([1, 2, 3]));
+    },
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  const view = new Uint8Array(new ArrayBuffer(10), 0, 0);
+  return promise_rejects_js(t, TypeError, reader.read(view));
+}, 'ReadableStream with byte source: reading into a zero-length view on a non-zero-length buffer rejects');
+
+async_test(t => {
+  const stream = new ReadableStream({
+    pull: t.step_func_done(c => {
+      // Detach it by reading into it
+      reader.read(c.byobRequest.view);
+
+      assert_throws_js(TypeError, () => c.byobRequest.respond(1),
+        'respond() must throw if the corresponding view has become detached');
+    }),
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  reader.read(new Uint8Array([4, 5, 6]));
+}, 'ReadableStream with byte source: respond() throws if the BYOB request\'s buffer has been detached (in the ' +
+   'readable state)');
+
+async_test(t => {
+  const stream = new ReadableStream({
+    pull: t.step_func_done(c => {
+      c.close();
+
+      // Detach it by reading into it
+      reader.read(c.byobRequest.view);
+
+      assert_throws_js(TypeError, () => c.byobRequest.respond(0),
+        'respond() must throw if the corresponding view has become detached');
+    }),
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  reader.read(new Uint8Array([4, 5, 6]));
+}, 'ReadableStream with byte source: respond() throws if the BYOB request\'s buffer has been detached (in the ' +
+   'closed state)');
+
+async_test(t => {
+  const stream = new ReadableStream({
+    pull: t.step_func_done(c => {
+      // Detach it by reading into it
+      const view = new Uint8Array([1, 2, 3]);
+      reader.read(view);
+
+      assert_throws_js(TypeError, () => c.byobRequest.respondWithNewView(view));
+    }),
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  reader.read(new Uint8Array([4, 5, 6]));
+}, 'ReadableStream with byte source: respondWithNewView() throws if the supplied view\'s buffer has been detached ' +
+    '(in the readable state)');
+
+async_test(t => {
+  const stream = new ReadableStream({
+    pull: t.step_func_done(c => {
+      const view = new Uint8Array();
+
+      assert_throws_js(TypeError, () => c.byobRequest.respondWithNewView(view));
+    }),
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  reader.read(new Uint8Array([4, 5, 6]));
+}, 'ReadableStream with byte source: respondWithNewView() throws if the supplied view\'s buffer is zero-length ' +
+    '(in the readable state)');
+
+async_test(t => {
+  const stream = new ReadableStream({
+    pull: t.step_func_done(c => {
+      const view = new Uint8Array(c.byobRequest.view.buffer, 0, 0);
+
+      assert_throws_js(TypeError, () => c.byobRequest.respondWithNewView(view));
+    }),
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  reader.read(new Uint8Array([4, 5, 6]));
+}, 'ReadableStream with byte source: respondWithNewView() throws if the supplied view is zero-length on a ' +
+    'non-zero-length buffer (in the readable state)');
+
+async_test(t => {
+  const stream = new ReadableStream({
+    pull: t.step_func_done(c => {
+      const view = c.byobRequest.view.subarray(1, 2);
+
+      assert_throws_js(RangeError, () => c.byobRequest.respondWithNewView(view));
+    }),
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  reader.read(new Uint8Array([4, 5, 6]));
+}, 'ReadableStream with byte source: respondWithNewView() throws if the supplied view has a different offset ' +
+   '(in the readable state)');
+
+async_test(t => {
+  const stream = new ReadableStream({
+    pull: t.step_func_done(c => {
+      c.close();
+
+      const view = c.byobRequest.view.subarray(1, 1);
+
+      assert_throws_js(RangeError, () => c.byobRequest.respondWithNewView(view));
+    }),
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  reader.read(new Uint8Array([4, 5, 6]));
+}, 'ReadableStream with byte source: respondWithNewView() throws if the supplied view has a different offset ' +
+   '(in the closed state)');
+
+async_test(t => {
+  const stream = new ReadableStream({
+    pull: t.step_func_done(c => {
+      const view = new Uint8Array(new ArrayBuffer(10), 0, 3);
+
+      assert_throws_js(RangeError, () => c.byobRequest.respondWithNewView(view));
+    }),
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  reader.read(new Uint8Array([4, 5, 6]));
+}, 'ReadableStream with byte source: respondWithNewView() throws if the supplied view\'s buffer has a ' +
+   'different length (in the readable state)');
+
+async_test(t => {
+  // Tests https://github.com/nodejs/node/issues/41886
+  const stream = new ReadableStream({
+    pull: t.step_func_done(c => {
+      const view = new Uint8Array(new ArrayBuffer(11), 0, 3);
+
+      assert_throws_js(RangeError, () => c.byobRequest.respondWithNewView(view));
+    }),
+    type: 'bytes',
+    autoAllocateChunkSize: 10
+  });
+  const reader = stream.getReader();
+
+  reader.read();
+}, 'ReadableStream with byte source: respondWithNewView() throws if the supplied view\'s buffer has a ' +
+   'different length (autoAllocateChunkSize)');
+
+async_test(t => {
+  const stream = new ReadableStream({
+    pull: t.step_func_done(c => {
+      const view = new Uint8Array(c.byobRequest.view.buffer, 0, 4);
+      view[0] = 20;
+      view[1] = 21;
+      view[2] = 22;
+      view[3] = 23;
+
+      assert_throws_js(RangeError, () => c.byobRequest.respondWithNewView(view));
+    }),
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  const buffer = new ArrayBuffer(10);
+  const view = new Uint8Array(buffer, 0, 3);
+  view[0] = 10;
+  view[1] = 11;
+  view[2] = 12;
+  reader.read(view);
+}, 'ReadableStream with byte source: respondWithNewView() throws if the supplied view has a larger length ' +
+   '(in the readable state)');
+
+async_test(t => {
+  const stream = new ReadableStream({
+    pull: t.step_func_done(c => {
+      c.close();
+
+      // Detach it by reading into it
+      const view = new Uint8Array([1, 2, 3]);
+      reader.read(view);
+
+      assert_throws_js(TypeError, () => c.byobRequest.respondWithNewView(view));
+    }),
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  reader.read(new Uint8Array([4, 5, 6]));
+}, 'ReadableStream with byte source: respondWithNewView() throws if the supplied view\'s buffer has been detached ' +
+   '(in the closed state)');
+
+async_test(t => {
+  const stream = new ReadableStream({
+    pull: t.step_func_done(c => {
+      const view = new Uint8Array();
+
+      c.close();
+
+      assert_throws_js(RangeError, () => c.byobRequest.respondWithNewView(view));
+    }),
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  reader.read(new Uint8Array([4, 5, 6]));
+}, 'ReadableStream with byte source: respondWithNewView() throws if the supplied view\'s buffer is zero-length ' +
+   '(in the closed state)');
+
+async_test(t => {
+  const stream = new ReadableStream({
+    pull: t.step_func_done(c => {
+      const view = new Uint8Array(c.byobRequest.view.buffer, 0, 1);
+
+      c.close();
+
+      assert_throws_js(TypeError, () => c.byobRequest.respondWithNewView(view));
+    }),
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  reader.read(new Uint8Array([4, 5, 6]));
+}, 'ReadableStream with byte source: respondWithNewView() throws if the supplied view is non-zero-length ' +
+   '(in the closed state)');
+
+async_test(t => {
+  const stream = new ReadableStream({
+    pull: t.step_func_done(c => {
+      const view = new Uint8Array(new ArrayBuffer(10), 0, 0);
+
+      c.close();
+
+      assert_throws_js(RangeError, () => c.byobRequest.respondWithNewView(view));
+    }),
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  reader.read(new Uint8Array([4, 5, 6]));
+}, 'ReadableStream with byte source: respondWithNewView() throws if the supplied view\'s buffer has a ' +
+   'different length (in the closed state)');
+
+async_test(t => {
+  const stream = new ReadableStream({
+    pull: t.step_func_done(c => {
+      // Detach it by reading into it
+      reader.read(c.byobRequest.view);
+
+      assert_throws_js(TypeError, () => c.enqueue(new Uint8Array([1])),
+        'enqueue() must throw if the BYOB request\'s buffer has become detached');
+    }),
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  reader.read(new Uint8Array([4, 5, 6]));
+}, 'ReadableStream with byte source: enqueue() throws if the BYOB request\'s buffer has been detached (in the ' +
+  'readable state)');
+
+async_test(t => {
+  const stream = new ReadableStream({
+    pull: t.step_func_done(c => {
+      c.close();
+
+      // Detach it by reading into it
+      reader.read(c.byobRequest.view);
+
+      assert_throws_js(TypeError, () => c.enqueue(new Uint8Array([1])),
+        'enqueue() must throw if the BYOB request\'s buffer has become detached');
+    }),
+    type: 'bytes'
+  });
+  const reader = stream.getReader({ mode: 'byob' });
+
+  reader.read(new Uint8Array([4, 5, 6]));
+}, 'ReadableStream with byte source: enqueue() throws if the BYOB request\'s buffer has been detached (in the ' +
+  'closed state)');

test/fixtures/wpt/streams/readable-byte-streams/construct-byob-request.any.js

@@ -0,0 +1,53 @@
+// META: global=window,worker,shadowrealm
+// META: script=../resources/rs-utils.js
+'use strict';
+
+// Prior to whatwg/stream#870 it was possible to construct a ReadableStreamBYOBRequest directly. This made it possible
+// to construct requests that were out-of-sync with the state of the ReadableStream. They could then be used to call
+// internal operations, resulting in asserts or bad behaviour. This file contains regression tests for the change.
+
+function getRealByteStreamController() {
+  let controller;
+  new ReadableStream({
+    start(c) {
+      controller = c;
+    },
+    type: 'bytes'
+  });
+  return controller;
+}
+
+// Create an object pretending to have prototype |prototype|, of type |type|. |type| is one of "undefined", "null",
+// "fake", or "real". "real" will call the realObjectCreator function to get a real instance of the object.
+function createDummyObject(prototype, type, realObjectCreator) {
+  switch (type) {
+    case 'undefined':
+      return undefined;
+
+    case 'null':
+      return null;
+
+    case 'fake':
+      return Object.create(prototype);
+
+    case 'real':
+      return realObjectCreator();
+  }
+
+  throw new Error('not reached');
+}
+
+const dummyTypes = ['undefined', 'null', 'fake', 'real'];
+
+for (const controllerType of dummyTypes) {
+  const controller = createDummyObject(ReadableByteStreamController.prototype, controllerType,
+                                        getRealByteStreamController);
+  for (const viewType of dummyTypes) {
+    const view = createDummyObject(Uint8Array.prototype, viewType, () => new Uint8Array(16));
+    test(() => {
+      assert_throws_js(TypeError, () => new ReadableStreamBYOBRequest(controller, view),
+                        'constructor should throw');
+    }, `ReadableStreamBYOBRequest constructor should throw when passed a ${controllerType} ` +
+        `ReadableByteStreamController and a ${viewType} view`);
+  }
+}

test/fixtures/wpt/streams/readable-byte-streams/enqueue-with-detached-buffer.any.js

@@ -0,0 +1,21 @@
+// META: global=window,worker,shadowrealm
+
+promise_test(async t => {
+  const error = new Error('cannot proceed');
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull: t.step_func((controller) => {
+      const buffer = controller.byobRequest.view.buffer;
+      // Detach the buffer.
+      structuredClone(buffer, { transfer: [buffer] });
+
+      // Try to enqueue with a new buffer.
+      assert_throws_js(TypeError, () => controller.enqueue(new Uint8Array([42])));
+
+      // If we got here the test passed.
+      controller.error(error);
+    })
+  });
+  const reader = rs.getReader({ mode: 'byob' });
+  await promise_rejects_exactly(t, error, reader.read(new Uint8Array(1)));
+}, 'enqueue after detaching byobRequest.view.buffer should throw');

test/fixtures/wpt/streams/readable-byte-streams/non-transferable-buffers.any.js

@@ -0,0 +1,70 @@
+// META: global=window,worker,shadowrealm
+'use strict';
+
+promise_test(async t => {
+  const rs = new ReadableStream({
+    pull: t.unreached_func('pull() should not be called'),
+    type: 'bytes'
+  });
+
+  const reader = rs.getReader({ mode: 'byob' });
+  const memory = new WebAssembly.Memory({ initial: 1 });
+  const view = new Uint8Array(memory.buffer, 0, 1);
+  await promise_rejects_js(t, TypeError, reader.read(view));
+}, 'ReadableStream with byte source: read() with a non-transferable buffer');
+
+promise_test(async t => {
+  const rs = new ReadableStream({
+    pull: t.unreached_func('pull() should not be called'),
+    type: 'bytes'
+  });
+
+  const reader = rs.getReader({ mode: 'byob' });
+  const memory = new WebAssembly.Memory({ initial: 1 });
+  const view = new Uint8Array(memory.buffer, 0, 1);
+  await promise_rejects_js(t, TypeError, reader.read(view, { min: 1 }));
+}, 'ReadableStream with byte source: fill() with a non-transferable buffer');
+
+test(t => {
+  let controller;
+  const rs = new ReadableStream({
+    start(c) {
+      controller = c;
+    },
+    pull: t.unreached_func('pull() should not be called'),
+    type: 'bytes'
+  });
+
+  const memory = new WebAssembly.Memory({ initial: 1 });
+  const view = new Uint8Array(memory.buffer, 0, 1);
+  assert_throws_js(TypeError, () => controller.enqueue(view));
+}, 'ReadableStream with byte source: enqueue() with a non-transferable buffer');
+
+promise_test(async t => {
+  let byobRequest;
+  let resolvePullCalledPromise;
+  const pullCalledPromise = new Promise(resolve => {
+    resolvePullCalledPromise = resolve;
+  });
+  const rs = new ReadableStream({
+    pull(controller) {
+      byobRequest = controller.byobRequest;
+      resolvePullCalledPromise();
+    },
+    type: 'bytes'
+  });
+
+  const memory = new WebAssembly.Memory({ initial: 1 });
+  // Make sure the backing buffers of both views have the same length
+  const byobView = new Uint8Array(new ArrayBuffer(memory.buffer.byteLength), 0, 1);
+  const newView = new Uint8Array(memory.buffer, byobView.byteOffset, byobView.byteLength);
+
+  const reader = rs.getReader({ mode: 'byob' });
+  reader.read(byobView).then(
+    t.unreached_func('read() should not resolve'),
+    t.unreached_func('read() should not reject')
+  );
+  await pullCalledPromise;
+
+  assert_throws_js(TypeError, () => byobRequest.respondWithNewView(newView));
+}, 'ReadableStream with byte source: respondWithNewView() with a non-transferable buffer');

test/fixtures/wpt/streams/readable-byte-streams/patched-global.any.js

@@ -0,0 +1,54 @@
+// META: global=window,worker,shadowrealm
+// META: script=../resources/test-utils.js
+'use strict';
+
+// Tests which patch the global environment are kept separate to avoid
+// interfering with other tests.
+
+promise_test(async (t) => {
+  let controller;
+  const rs = new ReadableStream({
+    type: 'bytes',
+    start(c) {
+      controller = c;
+    }
+  });
+  const reader = rs.getReader({mode: 'byob'});
+
+  const length = 0x4000;
+  const buffer = new ArrayBuffer(length);
+  const bigArray = new BigUint64Array(buffer, length - 8, 1);
+
+  const read1 = reader.read(new Uint8Array(new ArrayBuffer(0x100)));
+  const read2 = reader.read(bigArray);
+
+  let flag = false;
+  Object.defineProperty(Object.prototype, 'then', {
+    get: t.step_func(() => {
+      if (!flag) {
+        flag = true;
+        assert_equals(controller.byobRequest, null, 'byobRequest should be null after filling both views');
+      }
+    }),
+    configurable: true
+  });
+  t.add_cleanup(() => {
+    delete Object.prototype.then;
+  });
+
+  controller.enqueue(new Uint8Array(0x110).fill(0x42));
+  assert_true(flag, 'patched then() should be called');
+
+  // The first read() is filled entirely with 0x100 bytes
+  const result1 = await read1;
+  assert_false(result1.done, 'result1.done');
+  assert_typed_array_equals(result1.value, new Uint8Array(0x100).fill(0x42), 'result1.value');
+
+  // The second read() is filled with the remaining 0x10 bytes
+  const result2 = await read2;
+  assert_false(result2.done, 'result2.done');
+  assert_equals(result2.value.constructor, BigUint64Array, 'result2.value constructor');
+  assert_equals(result2.value.byteOffset, length - 8, 'result2.value byteOffset');
+  assert_equals(result2.value.length, 1, 'result2.value length');
+  assert_array_equals([...result2.value], [0x42424242_42424242n], 'result2.value contents');
+}, 'Patched then() sees byobRequest after filling all pending pull-into descriptors');

test/fixtures/wpt/streams/readable-byte-streams/read-min.any.js

@@ -0,0 +1,774 @@
+// META: global=window,worker,shadowrealm
+// META: script=../resources/rs-utils.js
+// META: script=../resources/test-utils.js
+'use strict';
+
+// View buffers are detached after pull() returns, so record the information at the time that pull() was called.
+function extractViewInfo(view) {
+  return {
+    constructor: view.constructor,
+    bufferByteLength: view.buffer.byteLength,
+    byteOffset: view.byteOffset,
+    byteLength: view.byteLength
+  };
+}
+
+promise_test(async t => {
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull: t.unreached_func('pull() should not be called'),
+  });
+  const reader = rs.getReader({ mode: 'byob' });
+  await promise_rejects_js(t, TypeError, reader.read(new Uint8Array(1), { min: 0 }));
+}, 'ReadableStream with byte source: read({ min }) rejects if min is 0');
+
+promise_test(async t => {
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull: t.unreached_func('pull() should not be called'),
+  });
+  const reader = rs.getReader({ mode: 'byob' });
+  await promise_rejects_js(t, TypeError, reader.read(new Uint8Array(1), { min: -1 }));
+}, 'ReadableStream with byte source: read({ min }) rejects if min is negative');
+
+promise_test(async t => {
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull: t.unreached_func('pull() should not be called'),
+  });
+  const reader = rs.getReader({ mode: 'byob' });
+  await promise_rejects_js(t, RangeError, reader.read(new Uint8Array(1), { min: 2 }));
+}, 'ReadableStream with byte source: read({ min }) rejects if min is larger than view\'s length (Uint8Array)');
+
+promise_test(async t => {
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull: t.unreached_func('pull() should not be called'),
+  });
+  const reader = rs.getReader({ mode: 'byob' });
+  await promise_rejects_js(t, RangeError, reader.read(new Uint16Array(1), { min: 2 }));
+}, 'ReadableStream with byte source: read({ min }) rejects if min is larger than view\'s length (Uint16Array)');
+
+promise_test(async t => {
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull: t.unreached_func('pull() should not be called'),
+  });
+  const reader = rs.getReader({ mode: 'byob' });
+  await promise_rejects_js(t, RangeError, reader.read(new DataView(new ArrayBuffer(1)), { min: 2 }));
+}, 'ReadableStream with byte source: read({ min }) rejects if min is larger than view\'s length (DataView)');
+
+promise_test(async t => {
+  let pullCount = 0;
+  const byobRequests = [];
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull: t.step_func((c) => {
+      const byobRequest = c.byobRequest;
+      const view = byobRequest.view;
+      byobRequests[pullCount] = {
+        nonNull: byobRequest !== null,
+        viewNonNull: view !== null,
+        viewInfo: extractViewInfo(view)
+      };
+      if (pullCount === 0) {
+        view[0] = 0x01;
+        view[1] = 0x02;
+        byobRequest.respond(2);
+      } else if (pullCount === 1) {
+        view[0] = 0x03;
+        byobRequest.respond(1);
+      } else if (pullCount === 2) {
+        view[0] = 0x04;
+        byobRequest.respond(1);
+      }
+      ++pullCount;
+    })
+  });
+  const reader = rs.getReader({ mode: 'byob' });
+  const read1 = reader.read(new Uint8Array(3), { min: 3 });
+  const read2 = reader.read(new Uint8Array(1));
+
+  const result1 = await read1;
+  assert_false(result1.done, 'first result should not be done');
+  assert_typed_array_equals(result1.value, new Uint8Array([0x01, 0x02, 0x03]), 'first result value');
+
+  const result2 = await read2;
+  assert_false(result2.done, 'second result should not be done');
+  assert_typed_array_equals(result2.value, new Uint8Array([0x04]), 'second result value');
+
+  assert_equals(pullCount, 3, 'pull() must have been called 3 times');
+
+  {
+    const byobRequest = byobRequests[0];
+    assert_true(byobRequest.nonNull, 'first byobRequest must not be null');
+    assert_true(byobRequest.viewNonNull, 'first byobRequest.view must not be null');
+    const viewInfo = byobRequest.viewInfo;
+    assert_equals(viewInfo.constructor, Uint8Array, 'first view.constructor should be Uint8Array');
+    assert_equals(viewInfo.bufferByteLength, 3, 'first view.buffer.byteLength should be 3');
+    assert_equals(viewInfo.byteOffset, 0, 'first view.byteOffset should be 0');
+    assert_equals(viewInfo.byteLength, 3, 'first view.byteLength should be 3');
+  }
+
+  {
+    const byobRequest = byobRequests[1];
+    assert_true(byobRequest.nonNull, 'second byobRequest must not be null');
+    assert_true(byobRequest.viewNonNull, 'second byobRequest.view must not be null');
+    const viewInfo = byobRequest.viewInfo;
+    assert_equals(viewInfo.constructor, Uint8Array, 'second view.constructor should be Uint8Array');
+    assert_equals(viewInfo.bufferByteLength, 3, 'second view.buffer.byteLength should be 3');
+    assert_equals(viewInfo.byteOffset, 2, 'second view.byteOffset should be 2');
+    assert_equals(viewInfo.byteLength, 1, 'second view.byteLength should be 1');
+  }
+
+  {
+    const byobRequest = byobRequests[2];
+    assert_true(byobRequest.nonNull, 'third byobRequest must not be null');
+    assert_true(byobRequest.viewNonNull, 'third byobRequest.view must not be null');
+    const viewInfo = byobRequest.viewInfo;
+    assert_equals(viewInfo.constructor, Uint8Array, 'third view.constructor should be Uint8Array');
+    assert_equals(viewInfo.bufferByteLength, 1, 'third view.buffer.byteLength should be 1');
+    assert_equals(viewInfo.byteOffset, 0, 'third view.byteOffset should be 0');
+    assert_equals(viewInfo.byteLength, 1, 'third view.byteLength should be 1');
+  }
+
+}, 'ReadableStream with byte source: read({ min }), then read()');
+
+promise_test(async t => {
+  let pullCount = 0;
+  const byobRequests = [];
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull: t.step_func((c) => {
+      const byobRequest = c.byobRequest;
+      const view = byobRequest.view;
+      byobRequests[pullCount] = {
+        nonNull: byobRequest !== null,
+        viewNonNull: view !== null,
+        viewInfo: extractViewInfo(view)
+      };
+      if (pullCount === 0) {
+        view[0] = 0x01;
+        view[1] = 0x02;
+        byobRequest.respond(2);
+      } else if (pullCount === 1) {
+        view[0] = 0x03;
+        byobRequest.respond(1);
+      }
+      ++pullCount;
+    })
+  });
+  const reader = rs.getReader({ mode: 'byob' });
+
+  const result = await reader.read(new DataView(new ArrayBuffer(3)), { min: 3 });
+  assert_false(result.done, 'result should not be done');
+  assert_equals(result.value.constructor, DataView, 'result.value must be a DataView');
+  assert_equals(result.value.byteOffset, 0, 'result.value.byteOffset');
+  assert_equals(result.value.byteLength, 3, 'result.value.byteLength');
+  assert_equals(result.value.buffer.byteLength, 3, 'result.value.buffer.byteLength');
+  assert_array_equals([...new Uint8Array(result.value.buffer)], [0x01, 0x02, 0x03], `result.value.buffer contents`);
+
+  assert_equals(pullCount, 2, 'pull() must have been called 2 times');
+
+  {
+    const byobRequest = byobRequests[0];
+    assert_true(byobRequest.nonNull, 'first byobRequest must not be null');
+    assert_true(byobRequest.viewNonNull, 'first byobRequest.view must not be null');
+    const viewInfo = byobRequest.viewInfo;
+    assert_equals(viewInfo.constructor, Uint8Array, 'first view.constructor should be Uint8Array');
+    assert_equals(viewInfo.bufferByteLength, 3, 'first view.buffer.byteLength should be 3');
+    assert_equals(viewInfo.byteOffset, 0, 'first view.byteOffset should be 0');
+    assert_equals(viewInfo.byteLength, 3, 'first view.byteLength should be 3');
+  }
+
+  {
+    const byobRequest = byobRequests[1];
+    assert_true(byobRequest.nonNull, 'second byobRequest must not be null');
+    assert_true(byobRequest.viewNonNull, 'second byobRequest.view must not be null');
+    const viewInfo = byobRequest.viewInfo;
+    assert_equals(viewInfo.constructor, Uint8Array, 'second view.constructor should be Uint8Array');
+    assert_equals(viewInfo.bufferByteLength, 3, 'second view.buffer.byteLength should be 3');
+    assert_equals(viewInfo.byteOffset, 2, 'second view.byteOffset should be 2');
+    assert_equals(viewInfo.byteLength, 1, 'second view.byteLength should be 1');
+  }
+
+}, 'ReadableStream with byte source: read({ min }) with a DataView');
+
+promise_test(async t => {
+  let pullCount = 0;
+  const byobRequests = [];
+  const rs = new ReadableStream({
+    type: 'bytes',
+    start: t.step_func((c) => {
+      c.enqueue(new Uint8Array([0x01]));
+    }),
+    pull: t.step_func((c) => {
+      const byobRequest = c.byobRequest;
+      const view = byobRequest.view;
+      byobRequests[pullCount] = {
+        nonNull: byobRequest !== null,
+        viewNonNull: view !== null,
+        viewInfo: extractViewInfo(view)
+      };
+      if (pullCount === 0) {
+        view[0] = 0x02;
+        view[1] = 0x03;
+        byobRequest.respond(2);
+      }
+      ++pullCount;
+    })
+  });
+  const reader = rs.getReader({ mode: 'byob' });
+
+  const result = await reader.read(new Uint8Array(3), { min: 3 });
+  assert_false(result.done, 'first result should not be done');
+  assert_typed_array_equals(result.value, new Uint8Array([0x01, 0x02, 0x03]), 'first result value');
+
+  assert_equals(pullCount, 1, 'pull() must have only been called once');
+
+  const byobRequest = byobRequests[0];
+  assert_true(byobRequest.nonNull, 'first byobRequest must not be null');
+  assert_true(byobRequest.viewNonNull, 'first byobRequest.view must not be null');
+  const viewInfo = byobRequest.viewInfo;
+  assert_equals(viewInfo.constructor, Uint8Array, 'first view.constructor should be Uint8Array');
+  assert_equals(viewInfo.bufferByteLength, 3, 'first view.buffer.byteLength should be 3');
+  assert_equals(viewInfo.byteOffset, 1, 'first view.byteOffset should be 1');
+  assert_equals(viewInfo.byteLength, 2, 'first view.byteLength should be 2');
+
+}, 'ReadableStream with byte source: enqueue(), then read({ min })');
+
+promise_test(async t => {
+  let pullCount = 0;
+  const byobRequests = [];
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull: t.step_func((c) => {
+      const byobRequest = c.byobRequest;
+      const view = byobRequest.view;
+      byobRequests[pullCount] = {
+        nonNull: byobRequest !== null,
+        viewNonNull: view !== null,
+        viewInfo: extractViewInfo(view)
+      };
+      if (pullCount === 0) {
+        c.enqueue(new Uint8Array([0x01, 0x02]));
+      } else if (pullCount === 1) {
+        c.enqueue(new Uint8Array([0x03]));
+      }
+      ++pullCount;
+    })
+  });
+  const reader = rs.getReader({ mode: 'byob' });
+
+  const result = await reader.read(new Uint8Array(3), { min: 3 });
+  assert_false(result.done, 'first result should not be done');
+  assert_typed_array_equals(result.value, new Uint8Array([0x01, 0x02, 0x03]), 'first result value');
+
+  assert_equals(pullCount, 2, 'pull() must have been called 2 times');
+
+  {
+    const byobRequest = byobRequests[0];
+    assert_true(byobRequest.nonNull, 'first byobRequest must not be null');
+    assert_true(byobRequest.viewNonNull, 'first byobRequest.view must not be null');
+    const viewInfo = byobRequest.viewInfo;
+    assert_equals(viewInfo.constructor, Uint8Array, 'first view.constructor should be Uint8Array');
+    assert_equals(viewInfo.bufferByteLength, 3, 'first view.buffer.byteLength should be 3');
+    assert_equals(viewInfo.byteOffset, 0, 'first view.byteOffset should be 0');
+    assert_equals(viewInfo.byteLength, 3, 'first view.byteLength should be 3');
+  }
+
+  {
+    const byobRequest = byobRequests[1];
+    assert_true(byobRequest.nonNull, 'second byobRequest must not be null');
+    assert_true(byobRequest.viewNonNull, 'second byobRequest.view must not be null');
+    const viewInfo = byobRequest.viewInfo;
+    assert_equals(viewInfo.constructor, Uint8Array, 'second view.constructor should be Uint8Array');
+    assert_equals(viewInfo.bufferByteLength, 3, 'second view.buffer.byteLength should be 3');
+    assert_equals(viewInfo.byteOffset, 2, 'second view.byteOffset should be 2');
+    assert_equals(viewInfo.byteLength, 1, 'second view.byteLength should be 1');
+  }
+
+}, 'ReadableStream with byte source: read({ min: 3 }) on a 3-byte Uint8Array, then multiple enqueue() up to 3 bytes');
+
+promise_test(async t => {
+  let pullCount = 0;
+  const byobRequests = [];
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull: t.step_func((c) => {
+      const byobRequest = c.byobRequest;
+      const view = byobRequest.view;
+      byobRequests[pullCount] = {
+        nonNull: byobRequest !== null,
+        viewNonNull: view !== null,
+        viewInfo: extractViewInfo(view)
+      };
+      if (pullCount === 0) {
+        c.enqueue(new Uint8Array([0x01, 0x02]));
+      } else if (pullCount === 1) {
+        c.enqueue(new Uint8Array([0x03]));
+      }
+      ++pullCount;
+    })
+  });
+  const reader = rs.getReader({ mode: 'byob' });
+
+  const result = await reader.read(new Uint8Array(5), { min: 3 });
+  assert_false(result.done, 'first result should not be done');
+  assert_typed_array_equals(result.value, new Uint8Array([0x01, 0x02, 0x03, 0, 0]).subarray(0, 3), 'first result value');
+
+  assert_equals(pullCount, 2, 'pull() must have been called 2 times');
+
+  {
+    const byobRequest = byobRequests[0];
+    assert_true(byobRequest.nonNull, 'first byobRequest must not be null');
+    assert_true(byobRequest.viewNonNull, 'first byobRequest.view must not be null');
+    const viewInfo = byobRequest.viewInfo;
+    assert_equals(viewInfo.constructor, Uint8Array, 'first view.constructor should be Uint8Array');
+    assert_equals(viewInfo.bufferByteLength, 5, 'first view.buffer.byteLength should be 5');
+    assert_equals(viewInfo.byteOffset, 0, 'first view.byteOffset should be 0');
+    assert_equals(viewInfo.byteLength, 5, 'first view.byteLength should be 5');
+  }
+
+  {
+    const byobRequest = byobRequests[1];
+    assert_true(byobRequest.nonNull, 'second byobRequest must not be null');
+    assert_true(byobRequest.viewNonNull, 'second byobRequest.view must not be null');
+    const viewInfo = byobRequest.viewInfo;
+    assert_equals(viewInfo.constructor, Uint8Array, 'second view.constructor should be Uint8Array');
+    assert_equals(viewInfo.bufferByteLength, 5, 'second view.buffer.byteLength should be 5');
+    assert_equals(viewInfo.byteOffset, 2, 'second view.byteOffset should be 2');
+    assert_equals(viewInfo.byteLength, 3, 'second view.byteLength should be 3');
+  }
+
+}, 'ReadableStream with byte source: read({ min: 3 }) on a 5-byte Uint8Array, then multiple enqueue() up to 3 bytes');
+
+promise_test(async t => {
+  let pullCount = 0;
+  const byobRequests = [];
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull: t.step_func((c) => {
+      const byobRequest = c.byobRequest;
+      const view = byobRequest.view;
+      byobRequests[pullCount] = {
+        nonNull: byobRequest !== null,
+        viewNonNull: view !== null,
+        viewInfo: extractViewInfo(view)
+      };
+      if (pullCount === 0) {
+        c.enqueue(new Uint8Array([0x01, 0x02]));
+      } else if (pullCount === 1) {
+        c.enqueue(new Uint8Array([0x03, 0x04]));
+      }
+      ++pullCount;
+    })
+  });
+  const reader = rs.getReader({ mode: 'byob' });
+
+  const result = await reader.read(new Uint8Array(5), { min: 3 });
+  assert_false(result.done, 'first result should not be done');
+  assert_typed_array_equals(result.value, new Uint8Array([0x01, 0x02, 0x03, 0x04, 0]).subarray(0, 4), 'first result value');
+
+  assert_equals(pullCount, 2, 'pull() must have been called 2 times');
+
+  {
+    const byobRequest = byobRequests[0];
+    assert_true(byobRequest.nonNull, 'first byobRequest must not be null');
+    assert_true(byobRequest.viewNonNull, 'first byobRequest.view must not be null');
+    const viewInfo = byobRequest.viewInfo;
+    assert_equals(viewInfo.constructor, Uint8Array, 'first view.constructor should be Uint8Array');
+    assert_equals(viewInfo.bufferByteLength, 5, 'first view.buffer.byteLength should be 5');
+    assert_equals(viewInfo.byteOffset, 0, 'first view.byteOffset should be 0');
+    assert_equals(viewInfo.byteLength, 5, 'first view.byteLength should be 5');
+  }
+
+  {
+    const byobRequest = byobRequests[1];
+    assert_true(byobRequest.nonNull, 'second byobRequest must not be null');
+    assert_true(byobRequest.viewNonNull, 'second byobRequest.view must not be null');
+    const viewInfo = byobRequest.viewInfo;
+    assert_equals(viewInfo.constructor, Uint8Array, 'second view.constructor should be Uint8Array');
+    assert_equals(viewInfo.bufferByteLength, 5, 'second view.buffer.byteLength should be 5');
+    assert_equals(viewInfo.byteOffset, 2, 'second view.byteOffset should be 2');
+    assert_equals(viewInfo.byteLength, 3, 'second view.byteLength should be 3');
+  }
+
+}, 'ReadableStream with byte source: read({ min: 3 }) on a 5-byte Uint8Array, then multiple enqueue() up to 4 bytes');
+
+promise_test(async t => {
+  const stream = new ReadableStream({
+    start(c) {
+      const view = new Uint8Array(16);
+      view[0] = 0x01;
+      view[8] = 0x02;
+      c.enqueue(view);
+    },
+    pull: t.unreached_func('pull() should not be called'),
+    type: 'bytes'
+  });
+
+  const byobReader = stream.getReader({ mode: 'byob' });
+  const result1 = await byobReader.read(new Uint8Array(8), { min: 8 });
+  assert_false(result1.done, 'result1.done');
+
+  const view1 = result1.value;
+  assert_equals(view1.constructor, Uint8Array, 'result1.value.constructor');
+  assert_equals(view1.buffer.byteLength, 8, 'result1.value.buffer.byteLength');
+  assert_equals(view1.byteOffset, 0, 'result1.value.byteOffset');
+  assert_equals(view1.byteLength, 8, 'result1.value.byteLength');
+  assert_equals(view1[0], 0x01, 'result1.value[0]');
+
+  byobReader.releaseLock();
+
+  const reader = stream.getReader();
+  const result2 = await reader.read();
+  assert_false(result2.done, 'result2.done');
+
+  const view2 = result2.value;
+  assert_equals(view2.constructor, Uint8Array, 'result2.value.constructor');
+  assert_equals(view2.buffer.byteLength, 16, 'result2.value.buffer.byteLength');
+  assert_equals(view2.byteOffset, 8, 'result2.value.byteOffset');
+  assert_equals(view2.byteLength, 8, 'result2.value.byteLength');
+  assert_equals(view2[0], 0x02, 'result2.value[0]');
+}, 'ReadableStream with byte source: enqueue(), read({ min }) partially, then read()');
+
+promise_test(async () => {
+  let pullCount = 0;
+  const byobRequestDefined = [];
+  let byobRequestViewDefined;
+
+  const stream = new ReadableStream({
+    async pull(c) {
+      byobRequestDefined.push(c.byobRequest !== null);
+      const initialByobRequest = c.byobRequest;
+
+      const transferredView = await transferArrayBufferView(c.byobRequest.view);
+      transferredView[0] = 0x01;
+      c.byobRequest.respondWithNewView(transferredView);
+
+      byobRequestDefined.push(c.byobRequest !== null);
+      byobRequestViewDefined = initialByobRequest.view !== null;
+
+      ++pullCount;
+    },
+    type: 'bytes'
+  });
+
+  const reader = stream.getReader({ mode: 'byob' });
+  const result = await reader.read(new Uint8Array(1), { min: 1 });
+  assert_false(result.done, 'result.done');
+  assert_equals(result.value.byteLength, 1, 'result.value.byteLength');
+  assert_equals(result.value[0], 0x01, 'result.value[0]');
+  assert_equals(pullCount, 1, 'pull() should be called only once');
+  assert_true(byobRequestDefined[0], 'byobRequest must not be null before respondWithNewView()');
+  assert_false(byobRequestDefined[1], 'byobRequest must be null after respondWithNewView()');
+  assert_false(byobRequestViewDefined, 'view of initial byobRequest must be null after respondWithNewView()');
+}, 'ReadableStream with byte source: read({ min }), then respondWithNewView() with a transferred ArrayBuffer');
+
+promise_test(async t => {
+  const stream = new ReadableStream({
+    start(c) {
+      c.close();
+    },
+    pull: t.unreached_func('pull() should not be called'),
+    type: 'bytes'
+  });
+
+  const reader = stream.getReader({ mode: 'byob' });
+
+  const result = await reader.read(new Uint8Array([0x01]), { min: 1 });
+  assert_true(result.done, 'result.done');
+  assert_typed_array_equals(result.value, new Uint8Array([0x01]).subarray(0, 0), 'result.value');
+
+  await reader.closed;
+}, 'ReadableStream with byte source: read({ min }) on a closed stream');
+
+promise_test(async t => {
+  let pullCount = 0;
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull: t.step_func((c) => {
+      if (pullCount === 0) {
+        c.byobRequest.view[0] = 0x01;
+        c.byobRequest.respond(1);
+      } else if (pullCount === 1) {
+        c.close();
+        c.byobRequest.respond(0);
+      }
+      ++pullCount;
+    })
+  });
+  const reader = rs.getReader({ mode: 'byob' });
+
+  const result = await reader.read(new Uint8Array(3), { min: 3 });
+  assert_true(result.done, 'result.done');
+  assert_typed_array_equals(result.value, new Uint8Array([0x01, 0, 0]).subarray(0, 1), 'result.value');
+
+  assert_equals(pullCount, 2, 'pull() must have been called 2 times');
+
+  await reader.closed;
+}, 'ReadableStream with byte source: read({ min }) when closed before view is filled');
+
+promise_test(async t => {
+  let pullCount = 0;
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull: t.step_func((c) => {
+      if (pullCount === 0) {
+        c.byobRequest.view[0] = 0x01;
+        c.byobRequest.view[1] = 0x02;
+        c.byobRequest.respond(2);
+      } else if (pullCount === 1) {
+        c.byobRequest.view[0] = 0x03;
+        c.byobRequest.respond(1);
+        c.close();
+      }
+      ++pullCount;
+    })
+  });
+  const reader = rs.getReader({ mode: 'byob' });
+
+  const result = await reader.read(new Uint8Array(3), { min: 3 });
+  assert_false(result.done, 'result.done');
+  assert_typed_array_equals(result.value, new Uint8Array([0x01, 0x02, 0x03]), 'result.value');
+
+  assert_equals(pullCount, 2, 'pull() must have been called 2 times');
+
+  await reader.closed;
+}, 'ReadableStream with byte source: read({ min }) when closed immediately after view is filled');
+
+promise_test(async t => {
+  const error1 = new Error('error1');
+  const stream = new ReadableStream({
+    start(c) {
+      c.error(error1);
+    },
+    pull: t.unreached_func('pull() should not be called'),
+    type: 'bytes'
+  });
+
+  const reader = stream.getReader({ mode: 'byob' });
+  const read = reader.read(new Uint8Array(1), { min: 1 });
+
+  await Promise.all([
+    promise_rejects_exactly(t, error1, read, 'read() must fail'),
+    promise_rejects_exactly(t, error1, reader.closed, 'closed must fail')
+  ]);
+}, 'ReadableStream with byte source: read({ min }) on an errored stream');
+
+promise_test(async t => {
+  const error1 = new Error('error1');
+  let controller;
+  const stream = new ReadableStream({
+    start(c) {
+      controller = c;
+    },
+    type: 'bytes'
+  });
+
+  const reader = stream.getReader({ mode: 'byob' });
+  const read = reader.read(new Uint8Array(1), { min: 1 });
+
+  controller.error(error1);
+
+  await Promise.all([
+    promise_rejects_exactly(t, error1, read, 'read() must fail'),
+    promise_rejects_exactly(t, error1, reader.closed, 'closed must fail')
+  ]);
+}, 'ReadableStream with byte source: read({ min }), then error()');
+
+promise_test(t => {
+  let cancelCount = 0;
+  let reason;
+
+  const passedReason = new TypeError('foo');
+
+  const stream = new ReadableStream({
+    pull: t.unreached_func('pull() should not be called'),
+    cancel(r) {
+      if (cancelCount === 0) {
+        reason = r;
+      }
+
+      ++cancelCount;
+
+      return 'bar';
+    },
+    type: 'bytes'
+  });
+
+  const reader = stream.getReader({ mode: 'byob' });
+
+  const readPromise = reader.read(new Uint8Array(1), { min: 1 }).then(result => {
+    assert_true(result.done, 'result.done');
+    assert_equals(result.value, undefined, 'result.value');
+  });
+
+  const cancelPromise = reader.cancel(passedReason).then(result => {
+    assert_equals(result, undefined, 'cancel() return value should be fulfilled with undefined');
+    assert_equals(cancelCount, 1, 'cancel() should be called only once');
+    assert_equals(reason, passedReason, 'reason should equal the passed reason');
+  });
+
+  return Promise.all([readPromise, cancelPromise]);
+}, 'ReadableStream with byte source: getReader(), read({ min }), then cancel()');
+
+promise_test(async t => {
+  let pullCount = 0;
+  let byobRequest;
+  const viewInfos = [];
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull: t.step_func((c) => {
+      byobRequest = c.byobRequest;
+
+      viewInfos.push(extractViewInfo(c.byobRequest.view));
+      c.byobRequest.view[0] = 0x01;
+      c.byobRequest.respond(1);
+      viewInfos.push(extractViewInfo(c.byobRequest.view));
+
+      ++pullCount;
+    })
+  });
+
+  await Promise.resolve();
+  assert_equals(pullCount, 0, 'pull() must not have been called yet');
+
+  const reader = rs.getReader({ mode: 'byob' });
+  const read = reader.read(new Uint8Array(3), { min: 3 });
+  assert_equals(pullCount, 1, 'pull() must have been called once');
+  assert_not_equals(byobRequest, null, 'byobRequest should not be null');
+  assert_equals(viewInfos[0].byteLength, 3, 'byteLength before respond() should be 3');
+  assert_equals(viewInfos[1].byteLength, 2, 'byteLength after respond() should be 2');
+
+  reader.cancel().catch(t.unreached_func('cancel() should not reject'));
+
+  const result = await read;
+  assert_true(result.done, 'result.done');
+  assert_equals(result.value, undefined, 'result.value');
+
+  assert_equals(pullCount, 1, 'pull() must only be called once');
+
+  await reader.closed;
+}, 'ReadableStream with byte source: cancel() with partially filled pending read({ min }) request');
+
+promise_test(async () => {
+  let pullCalled = false;
+
+  const stream = new ReadableStream({
+    start(c) {
+      const view = new Uint8Array(16);
+      view[7] = 0x01;
+      view[15] = 0x02;
+      c.enqueue(view);
+    },
+    pull() {
+      pullCalled = true;
+    },
+    type: 'bytes'
+  });
+
+  const reader = stream.getReader({ mode: 'byob' });
+
+  const result1 = await reader.read(new Uint8Array(8), { min: 8 });
+  assert_false(result1.done, 'result1.done');
+
+  const view1 = result1.value;
+  assert_equals(view1.byteOffset, 0, 'result1.value.byteOffset');
+  assert_equals(view1.byteLength, 8, 'result1.value.byteLength');
+  assert_equals(view1[7], 0x01, 'result1.value[7]');
+
+  const result2 = await reader.read(new Uint8Array(8), { min: 8 });
+  assert_false(pullCalled, 'pull() must not have been called');
+  assert_false(result2.done, 'result2.done');
+
+  const view2 = result2.value;
+  assert_equals(view2.byteOffset, 0, 'result2.value.byteOffset');
+  assert_equals(view2.byteLength, 8, 'result2.value.byteLength');
+  assert_equals(view2[7], 0x02, 'result2.value[7]');
+}, 'ReadableStream with byte source: enqueue(), then read({ min }) with smaller views');
+
+promise_test(async t => {
+  const stream = new ReadableStream({
+    start(c) {
+      c.enqueue(new Uint8Array([0xaa, 0xbb, 0xcc]));
+      c.close();
+    },
+    pull: t.unreached_func('pull() should not be called'),
+    type: 'bytes'
+  });
+
+  const reader = stream.getReader({ mode: 'byob' });
+
+  await promise_rejects_js(t, TypeError, reader.read(new Uint16Array(2), { min: 2 }), 'read() must fail');
+  await promise_rejects_js(t, TypeError, reader.closed, 'reader.closed should reject');
+}, 'ReadableStream with byte source: 3 byte enqueue(), then close(), then read({ min }) with 2-element Uint16Array must fail');
+
+promise_test(async t => {
+  let controller;
+  const stream = new ReadableStream({
+    start(c) {
+      controller = c;
+    },
+    pull: t.unreached_func('pull() should not be called'),
+    type: 'bytes'
+  });
+
+  const reader = stream.getReader({ mode: 'byob' });
+  const readPromise = reader.read(new Uint16Array(2), { min: 2 });
+
+  controller.enqueue(new Uint8Array([0xaa, 0xbb, 0xcc]));
+  assert_throws_js(TypeError, () => controller.close(), 'controller.close() must throw');
+
+  await promise_rejects_js(t, TypeError, readPromise, 'read() must fail');
+  await promise_rejects_js(t, TypeError, reader.closed, 'reader.closed must reject');
+}, 'ReadableStream with byte source: read({ min }) with 2-element Uint16Array, then 3 byte enqueue(), then close() must fail');
+
+promise_test(async t => {
+  let pullCount = 0;
+  let controller;
+  const rs = new ReadableStream({
+    type: 'bytes',
+    start: t.step_func((c) => {
+      controller = c;
+    }),
+    pull: t.step_func((c) => {
+      ++pullCount;
+    })
+  });
+
+  const [reader1, reader2] = rs.tee().map(branch => branch.getReader({ mode: 'byob' }));
+
+  await Promise.resolve();
+  assert_equals(pullCount, 0, 'pull() must not have been called yet');
+
+  const read1 = reader1.read(new Uint8Array(3), { min: 3 });
+  const read2 = reader2.read(new Uint8Array(1));
+
+  assert_equals(pullCount, 1, 'pull() must have been called once');
+  const byobRequest1 = controller.byobRequest;
+  assert_equals(byobRequest1.view.byteLength, 3, 'first byobRequest.view.byteLength should be 3');
+  byobRequest1.view[0] = 0x01;
+  byobRequest1.respond(1);
+
+  const result2 = await read2;
+  assert_false(result2.done, 'branch2 first read() should not be done');
+  assert_typed_array_equals(result2.value, new Uint8Array([0x01]), 'branch2 first read() value');
+
+  assert_equals(pullCount, 2, 'pull() must have been called 2 times');
+  const byobRequest2 = controller.byobRequest;
+  assert_equals(byobRequest2.view.byteLength, 2, 'second byobRequest.view.byteLength should be 2');
+  byobRequest2.view[0] = 0x02;
+  byobRequest2.view[1] = 0x03;
+  byobRequest2.respond(2);
+
+  const result1 = await read1;
+  assert_false(result1.done, 'branch1 read() should not be done');
+  assert_typed_array_equals(result1.value, new Uint8Array([0x01, 0x02, 0x03]), 'branch1 read() value');
+
+  const result3 = await reader2.read(new Uint8Array(2));
+  assert_equals(pullCount, 2, 'pull() must only be called 2 times');
+  assert_false(result3.done, 'branch2 second read() should not be done');
+  assert_typed_array_equals(result3.value, new Uint8Array([0x02, 0x03]), 'branch2 second read() value');
+}, 'ReadableStream with byte source: tee() with read({ min }) from branch1 and read() from branch2');

test/fixtures/wpt/streams/readable-byte-streams/respond-after-enqueue.any.js

@@ -0,0 +1,55 @@
+// META: global=window,worker,shadowrealm
+
+'use strict';
+
+// Repro for Blink bug https://crbug.com/1255762.
+promise_test(async () => {
+  const rs = new ReadableStream({
+    type: 'bytes',
+    autoAllocateChunkSize: 10,
+    pull(controller) {
+      controller.enqueue(new Uint8Array([1, 2, 3]));
+      controller.byobRequest.respond(10);
+    }
+  });
+
+  const reader = rs.getReader();
+  const {value, done} = await reader.read();
+  assert_false(done, 'done should not be true');
+  assert_array_equals(value, [1, 2, 3], 'value should be 3 bytes');
+}, 'byobRequest.respond() after enqueue() should not crash');
+
+promise_test(async () => {
+  const rs = new ReadableStream({
+    type: 'bytes',
+    autoAllocateChunkSize: 10,
+    pull(controller) {
+      const byobRequest = controller.byobRequest;
+      controller.enqueue(new Uint8Array([1, 2, 3]));
+      byobRequest.respond(10);
+    }
+  });
+
+  const reader = rs.getReader();
+  const {value, done} = await reader.read();
+  assert_false(done, 'done should not be true');
+  assert_array_equals(value, [1, 2, 3], 'value should be 3 bytes');
+}, 'byobRequest.respond() with cached byobRequest after enqueue() should not crash');
+
+promise_test(async () => {
+  const rs = new ReadableStream({
+    type: 'bytes',
+    autoAllocateChunkSize: 10,
+    pull(controller) {
+      controller.enqueue(new Uint8Array([1, 2, 3]));
+      controller.byobRequest.respond(2);
+    }
+  });
+
+  const reader = rs.getReader();
+  const [read1, read2] = await Promise.all([reader.read(), reader.read()]);
+  assert_false(read1.done, 'read1.done should not be true');
+  assert_array_equals(read1.value, [1, 2, 3], 'read1.value should be 3 bytes');
+  assert_false(read2.done, 'read2.done should not be true');
+  assert_array_equals(read2.value, [0, 0], 'read2.value should be 2 bytes');
+}, 'byobRequest.respond() after enqueue() with double read should not crash');

test/fixtures/wpt/streams/readable-byte-streams/tee.any.js

@@ -0,0 +1,969 @@
+// META: global=window,worker,shadowrealm
+// META: script=../resources/rs-utils.js
+// META: script=../resources/test-utils.js
+// META: script=../resources/recording-streams.js
+// META: script=../resources/rs-test-templates.js
+'use strict';
+
+test(() => {
+
+  const rs = new ReadableStream({ type: 'bytes' });
+  const result = rs.tee();
+
+  assert_true(Array.isArray(result), 'return value should be an array');
+  assert_equals(result.length, 2, 'array should have length 2');
+  assert_equals(result[0].constructor, ReadableStream, '0th element should be a ReadableStream');
+  assert_equals(result[1].constructor, ReadableStream, '1st element should be a ReadableStream');
+
+}, 'ReadableStream teeing with byte source: rs.tee() returns an array of two ReadableStreams');
+
+promise_test(async t => {
+
+  const rs = new ReadableStream({
+    type: 'bytes',
+    start(c) {
+      c.enqueue(new Uint8Array([0x01]));
+      c.enqueue(new Uint8Array([0x02]));
+      c.close();
+    }
+  });
+
+  const [branch1, branch2] = rs.tee();
+  const reader1 = branch1.getReader({ mode: 'byob' });
+  const reader2 = branch2.getReader({ mode: 'byob' });
+
+  reader2.closed.then(t.unreached_func('branch2 should not be closed'));
+
+  {
+    const result = await reader1.read(new Uint8Array(1));
+    assert_equals(result.done, false, 'done');
+    assert_typed_array_equals(result.value, new Uint8Array([0x01]), 'value');
+  }
+
+  {
+    const result = await reader1.read(new Uint8Array(1));
+    assert_equals(result.done, false, 'done');
+    assert_typed_array_equals(result.value, new Uint8Array([0x02]), 'value');
+  }
+
+  {
+    const result = await reader1.read(new Uint8Array(1));
+    assert_equals(result.done, true, 'done');
+    assert_typed_array_equals(result.value, new Uint8Array([0]).subarray(0, 0), 'value');
+  }
+
+  {
+    const result = await reader2.read(new Uint8Array(1));
+    assert_equals(result.done, false, 'done');
+    assert_typed_array_equals(result.value, new Uint8Array([0x01]), 'value');
+  }
+
+  await reader1.closed;
+
+}, 'ReadableStream teeing with byte source: should be able to read one branch to the end without affecting the other');
+
+promise_test(async () => {
+
+  let pullCount = 0;
+  const enqueuedChunk = new Uint8Array([0x01]);
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull(c) {
+      ++pullCount;
+      if (pullCount === 1) {
+        c.enqueue(enqueuedChunk);
+      }
+    }
+  });
+
+  const [branch1, branch2] = rs.tee();
+  const reader1 = branch1.getReader();
+  const reader2 = branch2.getReader();
+
+  const [result1, result2] = await Promise.all([reader1.read(), reader2.read()]);
+  assert_equals(result1.done, false, 'reader1 done');
+  assert_equals(result2.done, false, 'reader2 done');
+
+  const view1 = result1.value;
+  const view2 = result2.value;
+  assert_typed_array_equals(view1, new Uint8Array([0x01]), 'reader1 value');
+  assert_typed_array_equals(view2, new Uint8Array([0x01]), 'reader2 value');
+
+  assert_not_equals(view1.buffer, view2.buffer, 'chunks should have different buffers');
+  assert_not_equals(enqueuedChunk.buffer, view1.buffer, 'enqueued chunk and branch1\'s chunk should have different buffers');
+  assert_not_equals(enqueuedChunk.buffer, view2.buffer, 'enqueued chunk and branch2\'s chunk should have different buffers');
+
+}, 'ReadableStream teeing with byte source: chunks should be cloned for each branch');
+
+promise_test(async () => {
+
+  let pullCount = 0;
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull(c) {
+      ++pullCount;
+      if (pullCount === 1) {
+        c.byobRequest.view[0] = 0x01;
+        c.byobRequest.respond(1);
+      }
+    }
+  });
+
+  const [branch1, branch2] = rs.tee();
+  const reader1 = branch1.getReader({ mode: 'byob' });
+  const reader2 = branch2.getReader();
+  const buffer = new Uint8Array([42, 42, 42]).buffer;
+
+  {
+    const result = await reader1.read(new Uint8Array(buffer, 0, 1));
+    assert_equals(result.done, false, 'done');
+    assert_typed_array_equals(result.value, new Uint8Array([0x01, 42, 42]).subarray(0, 1), 'value');
+  }
+
+  {
+    const result = await reader2.read();
+    assert_equals(result.done, false, 'done');
+    assert_typed_array_equals(result.value, new Uint8Array([0x01]), 'value');
+  }
+
+}, 'ReadableStream teeing with byte source: chunks for BYOB requests from branch 1 should be cloned to branch 2');
+
+promise_test(async t => {
+
+  const theError = { name: 'boo!' };
+  const rs = new ReadableStream({
+    type: 'bytes',
+    start(c) {
+      c.enqueue(new Uint8Array([0x01]));
+      c.enqueue(new Uint8Array([0x02]));
+    },
+    pull() {
+      throw theError;
+    }
+  });
+
+  const [branch1, branch2] = rs.tee();
+  const reader1 = branch1.getReader({ mode: 'byob' });
+  const reader2 = branch2.getReader({ mode: 'byob' });
+
+  {
+    const result = await reader1.read(new Uint8Array(1));
+    assert_equals(result.done, false, 'first read from branch1 should not be done');
+    assert_typed_array_equals(result.value, new Uint8Array([0x01]), 'first read from branch1');
+  }
+
+  {
+    const result = await reader1.read(new Uint8Array(1));
+    assert_equals(result.done, false, 'second read from branch1 should not be done');
+    assert_typed_array_equals(result.value, new Uint8Array([0x02]), 'second read from branch1');
+  }
+
+  await promise_rejects_exactly(t, theError, reader1.read(new Uint8Array(1)));
+  await promise_rejects_exactly(t, theError, reader2.read(new Uint8Array(1)));
+
+  await Promise.all([
+    promise_rejects_exactly(t, theError, reader1.closed),
+    promise_rejects_exactly(t, theError, reader2.closed)
+  ]);
+
+}, 'ReadableStream teeing with byte source: errors in the source should propagate to both branches');
+
+promise_test(async () => {
+
+  const rs = new ReadableStream({
+    type: 'bytes',
+    start(c) {
+      c.enqueue(new Uint8Array([0x01]));
+      c.enqueue(new Uint8Array([0x02]));
+      c.close();
+    }
+  });
+
+  const [branch1, branch2] = rs.tee();
+  branch1.cancel();
+
+  const [chunks1, chunks2] = await Promise.all([readableStreamToArray(branch1), readableStreamToArray(branch2)]);
+  assert_array_equals(chunks1, [], 'branch1 should have no chunks');
+  assert_equals(chunks2.length, 2, 'branch2 should have two chunks');
+  assert_typed_array_equals(chunks2[0], new Uint8Array([0x01]), 'first chunk from branch2');
+  assert_typed_array_equals(chunks2[1], new Uint8Array([0x02]), 'second chunk from branch2');
+
+}, 'ReadableStream teeing with byte source: canceling branch1 should not impact branch2');
+
+promise_test(async () => {
+
+  const rs = new ReadableStream({
+    type: 'bytes',
+    start(c) {
+      c.enqueue(new Uint8Array([0x01]));
+      c.enqueue(new Uint8Array([0x02]));
+      c.close();
+    }
+  });
+
+  const [branch1, branch2] = rs.tee();
+  branch2.cancel();
+
+  const [chunks1, chunks2] = await Promise.all([readableStreamToArray(branch1), readableStreamToArray(branch2)]);
+  assert_equals(chunks1.length, 2, 'branch1 should have two chunks');
+  assert_typed_array_equals(chunks1[0], new Uint8Array([0x01]), 'first chunk from branch1');
+  assert_typed_array_equals(chunks1[1], new Uint8Array([0x02]), 'second chunk from branch1');
+  assert_array_equals(chunks2, [], 'branch2 should have no chunks');
+
+}, 'ReadableStream teeing with byte source: canceling branch2 should not impact branch1');
+
+templatedRSTeeCancel('ReadableStream teeing with byte source', (extras) => {
+  return new ReadableStream({ type: 'bytes', ...extras });
+});
+
+promise_test(async () => {
+
+  let controller;
+  const rs = new ReadableStream({
+    type: 'bytes',
+    start(c) {
+      controller = c;
+    }
+  });
+
+  const [branch1, branch2] = rs.tee();
+  const reader1 = branch1.getReader({ mode: 'byob' });
+  const reader2 = branch2.getReader({ mode: 'byob' });
+
+  const promise = Promise.all([reader1.closed, reader2.closed]);
+
+  controller.close();
+
+  // The branches are created with HWM 0, so we need to read from at least one of them
+  // to observe the stream becoming closed.
+  const read1 = await reader1.read(new Uint8Array(1));
+  assert_equals(read1.done, true, 'first read from branch1 should be done');
+
+  await promise;
+
+}, 'ReadableStream teeing with byte source: closing the original should close the branches');
+
+promise_test(async t => {
+
+  let controller;
+  const rs = new ReadableStream({
+    type: 'bytes',
+    start(c) {
+      controller = c;
+    }
+  });
+
+  const [branch1, branch2] = rs.tee();
+  const reader1 = branch1.getReader({ mode: 'byob' });
+  const reader2 = branch2.getReader({ mode: 'byob' });
+
+  const theError = { name: 'boo!' };
+  const promise = Promise.all([
+    promise_rejects_exactly(t, theError, reader1.closed),
+    promise_rejects_exactly(t, theError, reader2.closed)
+  ]);
+
+  controller.error(theError);
+  await promise;
+
+}, 'ReadableStream teeing with byte source: erroring the original should immediately error the branches');
+
+promise_test(async t => {
+
+  let controller;
+  const rs = new ReadableStream({
+    type: 'bytes',
+    start(c) {
+      controller = c;
+    }
+  });
+
+  const [branch1, branch2] = rs.tee();
+  const reader1 = branch1.getReader();
+  const reader2 = branch2.getReader();
+
+  const theError = { name: 'boo!' };
+  const promise = Promise.all([
+    promise_rejects_exactly(t, theError, reader1.read()),
+    promise_rejects_exactly(t, theError, reader2.read())
+  ]);
+
+  controller.error(theError);
+  await promise;
+
+}, 'ReadableStream teeing with byte source: erroring the original should error pending reads from default reader');
+
+promise_test(async t => {
+
+  let controller;
+  const rs = new ReadableStream({
+    type: 'bytes',
+    start(c) {
+      controller = c;
+    }
+  });
+
+  const [branch1, branch2] = rs.tee();
+  const reader1 = branch1.getReader({ mode: 'byob' });
+  const reader2 = branch2.getReader({ mode: 'byob' });
+
+  const theError = { name: 'boo!' };
+  const promise = Promise.all([
+    promise_rejects_exactly(t, theError, reader1.read(new Uint8Array(1))),
+    promise_rejects_exactly(t, theError, reader2.read(new Uint8Array(1)))
+  ]);
+
+  controller.error(theError);
+  await promise;
+
+}, 'ReadableStream teeing with byte source: erroring the original should error pending reads from BYOB reader');
+
+promise_test(async () => {
+
+  let controller;
+  const rs = new ReadableStream({
+    type: 'bytes',
+    start(c) {
+      controller = c;
+    }
+  });
+
+  const [branch1, branch2] = rs.tee();
+  const reader1 = branch1.getReader({ mode: 'byob' });
+  const reader2 = branch2.getReader({ mode: 'byob' });
+  const cancelPromise = reader2.cancel();
+
+  controller.enqueue(new Uint8Array([0x01]));
+
+  const read1 = await reader1.read(new Uint8Array(1));
+  assert_equals(read1.done, false, 'first read() from branch1 should not be done');
+  assert_typed_array_equals(read1.value, new Uint8Array([0x01]), 'first read() from branch1');
+
+  controller.close();
+
+  const read2 = await reader1.read(new Uint8Array(1));
+  assert_equals(read2.done, true, 'second read() from branch1 should be done');
+
+  await Promise.all([
+    reader1.closed,
+    cancelPromise
+  ]);
+
+}, 'ReadableStream teeing with byte source: canceling branch1 should finish when branch2 reads until end of stream');
+
+promise_test(async t => {
+
+  let controller;
+  const theError = { name: 'boo!' };
+  const rs = new ReadableStream({
+    type: 'bytes',
+    start(c) {
+      controller = c;
+    }
+  });
+
+  const [branch1, branch2] = rs.tee();
+  const reader1 = branch1.getReader({ mode: 'byob' });
+  const reader2 = branch2.getReader({ mode: 'byob' });
+  const cancelPromise = reader2.cancel();
+
+  controller.error(theError);
+
+  await Promise.all([
+    promise_rejects_exactly(t, theError, reader1.read(new Uint8Array(1))),
+    cancelPromise
+  ]);
+
+}, 'ReadableStream teeing with byte source: canceling branch1 should finish when original stream errors');
+
+promise_test(async () => {
+
+  const rs = recordingReadableStream({ type: 'bytes' });
+
+  // Create two branches, each with a HWM of 0. This should result in no chunks being pulled.
+  rs.tee();
+
+  await flushAsyncEvents();
+  assert_array_equals(rs.events, [], 'pull should not be called');
+
+}, 'ReadableStream teeing with byte source: should not pull any chunks if no branches are reading');
+
+promise_test(async () => {
+
+  const rs = recordingReadableStream({
+    type: 'bytes',
+    pull(controller) {
+      controller.enqueue(new Uint8Array([0x01]));
+    }
+  });
+
+  const [reader1, reader2] = rs.tee().map(branch => branch.getReader({ mode: 'byob' }));
+  await Promise.all([
+    reader1.read(new Uint8Array(1)),
+    reader2.read(new Uint8Array(1))
+  ]);
+  assert_array_equals(rs.events, ['pull'], 'pull should be called once');
+
+}, 'ReadableStream teeing with byte source: should only pull enough to fill the emptiest queue');
+
+promise_test(async t => {
+
+  const rs = recordingReadableStream({ type: 'bytes' });
+  const theError = { name: 'boo!' };
+
+  rs.controller.error(theError);
+
+  const [reader1, reader2] = rs.tee().map(branch => branch.getReader({ mode: 'byob' }));
+
+  await flushAsyncEvents();
+  assert_array_equals(rs.events, [], 'pull should not be called');
+
+  await Promise.all([
+    promise_rejects_exactly(t, theError, reader1.closed),
+    promise_rejects_exactly(t, theError, reader2.closed)
+  ]);
+
+}, 'ReadableStream teeing with byte source: should not pull when original is already errored');
+
+for (const branch of [1, 2]) {
+  promise_test(async t => {
+
+    const rs = recordingReadableStream({ type: 'bytes' });
+    const theError = { name: 'boo!' };
+
+    const [reader1, reader2] = rs.tee().map(branch => branch.getReader({ mode: 'byob' }));
+
+    await flushAsyncEvents();
+    assert_array_equals(rs.events, [], 'pull should not be called');
+
+    const reader = (branch === 1) ? reader1 : reader2;
+    const read1 = reader.read(new Uint8Array(1));
+
+    await flushAsyncEvents();
+    assert_array_equals(rs.events, ['pull'], 'pull should be called once');
+
+    rs.controller.error(theError);
+
+    await Promise.all([
+      promise_rejects_exactly(t, theError, read1),
+      promise_rejects_exactly(t, theError, reader1.closed),
+      promise_rejects_exactly(t, theError, reader2.closed)
+    ]);
+
+    await flushAsyncEvents();
+    assert_array_equals(rs.events, ['pull'], 'pull should be called once');
+
+  }, `ReadableStream teeing with byte source: stops pulling when original stream errors while branch ${branch} is reading`);
+}
+
+promise_test(async t => {
+
+  const rs = recordingReadableStream({ type: 'bytes' });
+  const theError = { name: 'boo!' };
+
+  const [reader1, reader2] = rs.tee().map(branch => branch.getReader({ mode: 'byob' }));
+
+  await flushAsyncEvents();
+  assert_array_equals(rs.events, [], 'pull should not be called');
+
+  const read1 = reader1.read(new Uint8Array(1));
+  const read2 = reader2.read(new Uint8Array(1));
+
+  await flushAsyncEvents();
+  assert_array_equals(rs.events, ['pull'], 'pull should be called once');
+
+  rs.controller.error(theError);
+
+  await Promise.all([
+    promise_rejects_exactly(t, theError, read1),
+    promise_rejects_exactly(t, theError, read2),
+    promise_rejects_exactly(t, theError, reader1.closed),
+    promise_rejects_exactly(t, theError, reader2.closed)
+  ]);
+
+  await flushAsyncEvents();
+  assert_array_equals(rs.events, ['pull'], 'pull should be called once');
+
+}, 'ReadableStream teeing with byte source: stops pulling when original stream errors while both branches are reading');
+
+promise_test(async () => {
+
+  const rs = recordingReadableStream({ type: 'bytes' });
+
+  const [reader1, reader2] = rs.tee().map(branch => branch.getReader({ mode: 'byob' }));
+
+  const read1 = reader1.read(new Uint8Array([0x11]));
+  const read2 = reader2.read(new Uint8Array([0x22]));
+
+  const cancel1 = reader1.cancel();
+  await flushAsyncEvents();
+  const cancel2 = reader2.cancel();
+
+  const result1 = await read1;
+  assert_object_equals(result1, { value: undefined, done: true });
+  const result2 = await read2;
+  assert_object_equals(result2, { value: undefined, done: true });
+
+  await Promise.all([cancel1, cancel2]);
+
+}, 'ReadableStream teeing with byte source: canceling both branches in sequence with delay');
+
+promise_test(async t => {
+
+  const theError = { name: 'boo!' };
+  const rs = new ReadableStream({
+    type: 'bytes',
+    cancel() {
+      throw theError;
+    }
+  });
+
+  const [reader1, reader2] = rs.tee().map(branch => branch.getReader({ mode: 'byob' }));
+
+  const read1 = reader1.read(new Uint8Array([0x11]));
+  const read2 = reader2.read(new Uint8Array([0x22]));
+
+  const cancel1 = reader1.cancel();
+  await flushAsyncEvents();
+  const cancel2 = reader2.cancel();
+
+  const result1 = await read1;
+  assert_object_equals(result1, { value: undefined, done: true });
+  const result2 = await read2;
+  assert_object_equals(result2, { value: undefined, done: true });
+
+  await Promise.all([
+    promise_rejects_exactly(t, theError, cancel1),
+    promise_rejects_exactly(t, theError, cancel2)
+  ]);
+
+}, 'ReadableStream teeing with byte source: failing to cancel when canceling both branches in sequence with delay');
+
+promise_test(async () => {
+
+  let cancelResolve;
+  const cancelCalled = new Promise((resolve) => {
+    cancelResolve = resolve;
+  });
+  const rs = recordingReadableStream({
+    type: 'bytes',
+    cancel() {
+      cancelResolve();
+    }
+  });
+
+  const [reader1, reader2] = rs.tee().map(branch => branch.getReader({ mode: 'byob' }));
+
+  const read1 = reader1.read(new Uint8Array([0x11]));
+  await flushAsyncEvents();
+  const read2 = reader2.read(new Uint8Array([0x22]));
+  await flushAsyncEvents();
+
+  // We are reading into branch1's buffer.
+  const byobRequest1 = rs.controller.byobRequest;
+  assert_not_equals(byobRequest1, null);
+  assert_typed_array_equals(byobRequest1.view, new Uint8Array([0x11]), 'byobRequest1.view');
+
+  // Cancelling branch1 should not affect the BYOB request.
+  const cancel1 = reader1.cancel();
+  const result1 = await read1;
+  assert_equals(result1.done, true);
+  assert_equals(result1.value, undefined);
+  await flushAsyncEvents();
+  const byobRequest2 = rs.controller.byobRequest;
+  assert_typed_array_equals(byobRequest2.view, new Uint8Array([0x11]), 'byobRequest2.view');
+
+  // Cancelling branch1 should invalidate the BYOB request.
+  const cancel2 = reader2.cancel();
+  await cancelCalled;
+  const byobRequest3 = rs.controller.byobRequest;
+  assert_equals(byobRequest3, null);
+  const result2 = await read2;
+  assert_equals(result2.done, true);
+  assert_equals(result2.value, undefined);
+
+  await Promise.all([cancel1, cancel2]);
+
+}, 'ReadableStream teeing with byte source: read from branch1 and branch2, cancel branch1, cancel branch2');
+
+promise_test(async () => {
+
+  let cancelResolve;
+  const cancelCalled = new Promise((resolve) => {
+    cancelResolve = resolve;
+  });
+  const rs = recordingReadableStream({
+    type: 'bytes',
+    cancel() {
+      cancelResolve();
+    }
+  });
+
+  const [reader1, reader2] = rs.tee().map(branch => branch.getReader({ mode: 'byob' }));
+
+  const read1 = reader1.read(new Uint8Array([0x11]));
+  await flushAsyncEvents();
+  const read2 = reader2.read(new Uint8Array([0x22]));
+  await flushAsyncEvents();
+
+  // We are reading into branch1's buffer.
+  const byobRequest1 = rs.controller.byobRequest;
+  assert_not_equals(byobRequest1, null);
+  assert_typed_array_equals(byobRequest1.view, new Uint8Array([0x11]), 'byobRequest1.view');
+
+  // Cancelling branch2 should not affect the BYOB request.
+  const cancel2 = reader2.cancel();
+  const result2 = await read2;
+  assert_equals(result2.done, true);
+  assert_equals(result2.value, undefined);
+  await flushAsyncEvents();
+  const byobRequest2 = rs.controller.byobRequest;
+  assert_typed_array_equals(byobRequest2.view, new Uint8Array([0x11]), 'byobRequest2.view');
+
+  // Cancelling branch1 should invalidate the BYOB request.
+  const cancel1 = reader1.cancel();
+  await cancelCalled;
+  const byobRequest3 = rs.controller.byobRequest;
+  assert_equals(byobRequest3, null);
+  const result1 = await read1;
+  assert_equals(result1.done, true);
+  assert_equals(result1.value, undefined);
+
+  await Promise.all([cancel1, cancel2]);
+
+}, 'ReadableStream teeing with byte source: read from branch1 and branch2, cancel branch2, cancel branch1');
+
+promise_test(async () => {
+
+  const rs = recordingReadableStream({ type: 'bytes' });
+
+  const [reader1, reader2] = rs.tee().map(branch => branch.getReader({ mode: 'byob' }));
+
+  const read1 = reader1.read(new Uint8Array([0x11]));
+  await flushAsyncEvents();
+  const read2 = reader2.read(new Uint8Array([0x22]));
+  await flushAsyncEvents();
+
+  // We are reading into branch1's buffer.
+  assert_typed_array_equals(rs.controller.byobRequest.view, new Uint8Array([0x11]), 'first byobRequest.view');
+
+  // Cancelling branch2 should not affect the BYOB request.
+  reader2.cancel();
+  const result2 = await read2;
+  assert_equals(result2.done, true);
+  assert_equals(result2.value, undefined);
+  await flushAsyncEvents();
+  assert_typed_array_equals(rs.controller.byobRequest.view, new Uint8Array([0x11]), 'second byobRequest.view');
+
+  // Respond to the BYOB request.
+  rs.controller.byobRequest.view[0] = 0x33;
+  rs.controller.byobRequest.respond(1);
+
+  // branch1 should receive the read chunk.
+  const result1 = await read1;
+  assert_equals(result1.done, false);
+  assert_typed_array_equals(result1.value, new Uint8Array([0x33]), 'first read() from branch1');
+
+}, 'ReadableStream teeing with byte source: read from branch1 and branch2, cancel branch2, enqueue to branch1');
+
+promise_test(async () => {
+
+  const rs = recordingReadableStream({ type: 'bytes' });
+
+  const [reader1, reader2] = rs.tee().map(branch => branch.getReader({ mode: 'byob' }));
+
+  const read1 = reader1.read(new Uint8Array([0x11]));
+  await flushAsyncEvents();
+  const read2 = reader2.read(new Uint8Array([0x22]));
+  await flushAsyncEvents();
+
+  // We are reading into branch1's buffer.
+  assert_typed_array_equals(rs.controller.byobRequest.view, new Uint8Array([0x11]), 'first byobRequest.view');
+
+  // Cancelling branch1 should not affect the BYOB request.
+  reader1.cancel();
+  const result1 = await read1;
+  assert_equals(result1.done, true);
+  assert_equals(result1.value, undefined);
+  await flushAsyncEvents();
+  assert_typed_array_equals(rs.controller.byobRequest.view, new Uint8Array([0x11]), 'second byobRequest.view');
+
+  // Respond to the BYOB request.
+  rs.controller.byobRequest.view[0] = 0x33;
+  rs.controller.byobRequest.respond(1);
+
+  // branch2 should receive the read chunk.
+  const result2 = await read2;
+  assert_equals(result2.done, false);
+  assert_typed_array_equals(result2.value, new Uint8Array([0x33]), 'first read() from branch2');
+
+}, 'ReadableStream teeing with byte source: read from branch1 and branch2, cancel branch1, respond to branch2');
+
+promise_test(async () => {
+
+  let pullCount = 0;
+  const byobRequestDefined = [];
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull(c) {
+      ++pullCount;
+      byobRequestDefined.push(c.byobRequest !== null);
+      c.enqueue(new Uint8Array([pullCount]));
+    }
+  });
+
+  const [branch1, _] = rs.tee();
+  const reader1 = branch1.getReader({ mode: 'byob' });
+
+  const result1 = await reader1.read(new Uint8Array([0x11]));
+  assert_equals(result1.done, false, 'first read should not be done');
+  assert_typed_array_equals(result1.value, new Uint8Array([0x1]), 'first read');
+  assert_equals(pullCount, 1, 'pull() should be called once');
+  assert_equals(byobRequestDefined[0], true, 'should have created a BYOB request for first read');
+
+  reader1.releaseLock();
+  const reader2 = branch1.getReader();
+
+  const result2 = await reader2.read();
+  assert_equals(result2.done, false, 'second read should not be done');
+  assert_typed_array_equals(result2.value, new Uint8Array([0x2]), 'second read');
+  assert_equals(pullCount, 2, 'pull() should be called twice');
+  assert_equals(byobRequestDefined[1], false, 'should not have created a BYOB request for second read');
+
+}, 'ReadableStream teeing with byte source: pull with BYOB reader, then pull with default reader');
+
+promise_test(async () => {
+
+  let pullCount = 0;
+  const byobRequestDefined = [];
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull(c) {
+      ++pullCount;
+      byobRequestDefined.push(c.byobRequest !== null);
+      c.enqueue(new Uint8Array([pullCount]));
+    }
+  });
+
+  const [branch1, _] = rs.tee();
+  const reader1 = branch1.getReader();
+
+  const result1 = await reader1.read();
+  assert_equals(result1.done, false, 'first read should not be done');
+  assert_typed_array_equals(result1.value, new Uint8Array([0x1]), 'first read');
+  assert_equals(pullCount, 1, 'pull() should be called once');
+  assert_equals(byobRequestDefined[0], false, 'should not have created a BYOB request for first read');
+
+  reader1.releaseLock();
+  const reader2 = branch1.getReader({ mode: 'byob' });
+
+  const result2 = await reader2.read(new Uint8Array([0x22]));
+  assert_equals(result2.done, false, 'second read should not be done');
+  assert_typed_array_equals(result2.value, new Uint8Array([0x2]), 'second read');
+  assert_equals(pullCount, 2, 'pull() should be called twice');
+  assert_equals(byobRequestDefined[1], true, 'should have created a BYOB request for second read');
+
+}, 'ReadableStream teeing with byte source: pull with default reader, then pull with BYOB reader');
+
+promise_test(async () => {
+
+  const rs = recordingReadableStream({
+    type: 'bytes'
+  });
+  const [reader1, reader2] = rs.tee().map(branch => branch.getReader({ mode: 'byob' }));
+
+  // Wait for each branch's start() promise to resolve.
+  await flushAsyncEvents();
+
+  const read2 = reader2.read(new Uint8Array([0x22]));
+  const read1 = reader1.read(new Uint8Array([0x11]));
+  await flushAsyncEvents();
+
+  // branch2 should provide the BYOB request.
+  const byobRequest = rs.controller.byobRequest;
+  assert_typed_array_equals(byobRequest.view, new Uint8Array([0x22]), 'first BYOB request');
+  byobRequest.view[0] = 0x01;
+  byobRequest.respond(1);
+
+  const result1 = await read1;
+  assert_equals(result1.done, false, 'first read should not be done');
+  assert_typed_array_equals(result1.value, new Uint8Array([0x1]), 'first read');
+
+  const result2 = await read2;
+  assert_equals(result2.done, false, 'second read should not be done');
+  assert_typed_array_equals(result2.value, new Uint8Array([0x1]), 'second read');
+
+}, 'ReadableStream teeing with byte source: read from branch2, then read from branch1');
+
+promise_test(async () => {
+
+  const rs = recordingReadableStream({ type: 'bytes' });
+  const [branch1, branch2] = rs.tee();
+  const reader1 = branch1.getReader();
+  const reader2 = branch2.getReader({ mode: 'byob' });
+  await flushAsyncEvents();
+
+  const read1 = reader1.read();
+  const read2 = reader2.read(new Uint8Array([0x22]));
+  await flushAsyncEvents();
+
+  // There should be no BYOB request.
+  assert_equals(rs.controller.byobRequest, null, 'first BYOB request');
+
+  // Close the stream.
+  rs.controller.close();
+
+  const result1 = await read1;
+  assert_equals(result1.done, true, 'read from branch1 should be done');
+  assert_equals(result1.value, undefined, 'read from branch1');
+
+  // branch2 should get its buffer back.
+  const result2 = await read2;
+  assert_equals(result2.done, true, 'read from branch2 should be done');
+  assert_typed_array_equals(result2.value, new Uint8Array([0x22]).subarray(0, 0), 'read from branch2');
+
+}, 'ReadableStream teeing with byte source: read from branch1 with default reader, then close while branch2 has pending BYOB read');
+
+promise_test(async () => {
+
+  const rs = recordingReadableStream({ type: 'bytes' });
+  const [branch1, branch2] = rs.tee();
+  const reader1 = branch1.getReader({ mode: 'byob' });
+  const reader2 = branch2.getReader();
+  await flushAsyncEvents();
+
+  const read2 = reader2.read();
+  const read1 = reader1.read(new Uint8Array([0x11]));
+  await flushAsyncEvents();
+
+  // There should be no BYOB request.
+  assert_equals(rs.controller.byobRequest, null, 'first BYOB request');
+
+  // Close the stream.
+  rs.controller.close();
+
+  const result2 = await read2;
+  assert_equals(result2.done, true, 'read from branch2 should be done');
+  assert_equals(result2.value, undefined, 'read from branch2');
+
+  // branch1 should get its buffer back.
+  const result1 = await read1;
+  assert_equals(result1.done, true, 'read from branch1 should be done');
+  assert_typed_array_equals(result1.value, new Uint8Array([0x11]).subarray(0, 0), 'read from branch1');
+
+}, 'ReadableStream teeing with byte source: read from branch2 with default reader, then close while branch1 has pending BYOB read');
+
+promise_test(async () => {
+
+  const rs = recordingReadableStream({ type: 'bytes' });
+  const [reader1, reader2] = rs.tee().map(branch => branch.getReader({ mode: 'byob' }));
+  await flushAsyncEvents();
+
+  const read1 = reader1.read(new Uint8Array([0x11]));
+  const read2 = reader2.read(new Uint8Array([0x22]));
+  await flushAsyncEvents();
+
+  // branch1 should provide the BYOB request.
+  const byobRequest = rs.controller.byobRequest;
+  assert_typed_array_equals(byobRequest.view, new Uint8Array([0x11]), 'first BYOB request');
+
+  // Close the stream.
+  rs.controller.close();
+  byobRequest.respond(0);
+
+  // Both branches should get their buffers back.
+  const result1 = await read1;
+  assert_equals(result1.done, true, 'first read should be done');
+  assert_typed_array_equals(result1.value, new Uint8Array([0x11]).subarray(0, 0), 'first read');
+
+  const result2 = await read2;
+  assert_equals(result2.done, true, 'second read should be done');
+  assert_typed_array_equals(result2.value, new Uint8Array([0x22]).subarray(0, 0), 'second read');
+
+}, 'ReadableStream teeing with byte source: close when both branches have pending BYOB reads');
+
+promise_test(async () => {
+
+  const rs = recordingReadableStream({ type: 'bytes' });
+
+  const [reader1, reader2] = rs.tee().map(branch => branch.getReader());
+  const branch1Reads = [reader1.read(), reader1.read()];
+  const branch2Reads = [reader2.read(), reader2.read()];
+
+  await flushAsyncEvents();
+  rs.controller.enqueue(new Uint8Array([0x11]));
+  rs.controller.close();
+
+  const result1 = await branch1Reads[0];
+  assert_equals(result1.done, false, 'first read() from branch1 should be not done');
+  assert_typed_array_equals(result1.value, new Uint8Array([0x11]), 'first chunk from branch1 should be correct');
+  const result2 = await branch2Reads[0];
+  assert_equals(result2.done, false, 'first read() from branch2 should be not done');
+  assert_typed_array_equals(result2.value, new Uint8Array([0x11]), 'first chunk from branch2 should be correct');
+
+  assert_object_equals(await branch1Reads[1], { value: undefined, done: true }, 'second read() from branch1 should be done');
+  assert_object_equals(await branch2Reads[1], { value: undefined, done: true }, 'second read() from branch2 should be done');
+
+}, 'ReadableStream teeing with byte source: enqueue() and close() while both branches are pulling');
+
+promise_test(async () => {
+
+  const rs = recordingReadableStream({ type: 'bytes' });
+
+  const [reader1, reader2] = rs.tee().map(branch => branch.getReader({ mode: 'byob' }));
+  const branch1Reads = [reader1.read(new Uint8Array(1)), reader1.read(new Uint8Array(1))];
+  const branch2Reads = [reader2.read(new Uint8Array(1)), reader2.read(new Uint8Array(1))];
+
+  await flushAsyncEvents();
+  rs.controller.byobRequest.view[0] = 0x11;
+  rs.controller.byobRequest.respond(1);
+  rs.controller.close();
+
+  const result1 = await branch1Reads[0];
+  assert_equals(result1.done, false, 'first read() from branch1 should be not done');
+  assert_typed_array_equals(result1.value, new Uint8Array([0x11]), 'first chunk from branch1 should be correct');
+  const result2 = await branch2Reads[0];
+  assert_equals(result2.done, false, 'first read() from branch2 should be not done');
+  assert_typed_array_equals(result2.value, new Uint8Array([0x11]), 'first chunk from branch2 should be correct');
+
+  const result3 = await branch1Reads[1];
+  assert_equals(result3.done, true, 'second read() from branch1 should be done');
+  assert_typed_array_equals(result3.value, new Uint8Array([0]).subarray(0, 0), 'second chunk from branch1 should be correct');
+  const result4 = await branch2Reads[1];
+  assert_equals(result4.done, true, 'second read() from branch2 should be done');
+  assert_typed_array_equals(result4.value, new Uint8Array([0]).subarray(0, 0), 'second chunk from branch2 should be correct');
+
+}, 'ReadableStream teeing with byte source: respond() and close() while both branches are pulling');
+
+promise_test(async t => {
+  let pullCount = 0;
+  const arrayBuffer = new Uint8Array([0x01, 0x02, 0x03]).buffer;
+  const enqueuedChunk = new Uint8Array(arrayBuffer, 2);
+  assert_equals(enqueuedChunk.length, 1);
+  assert_equals(enqueuedChunk.byteOffset, 2);
+  const rs = new ReadableStream({
+    type: 'bytes',
+    pull(c) {
+      ++pullCount;
+      if (pullCount === 1) {
+        c.enqueue(enqueuedChunk);
+      }
+    }
+  });
+
+  const [branch1, branch2] = rs.tee();
+  const reader1 = branch1.getReader();
+  const reader2 = branch2.getReader();
+
+  const [result1, result2] = await Promise.all([reader1.read(), reader2.read()]);
+  assert_equals(result1.done, false, 'reader1 done');
+  assert_equals(result2.done, false, 'reader2 done');
+
+  const view1 = result1.value;
+  const view2 = result2.value;
+  // The first stream has the transferred buffer, but the second stream has the
+  // cloned buffer.
+  const underlying = new Uint8Array([0x01, 0x02, 0x03]).buffer;
+  assert_typed_array_equals(view1, new Uint8Array(underlying, 2), 'reader1 value');
+  assert_typed_array_equals(view2, new Uint8Array([0x03]), 'reader2 value');
+}, 'ReadableStream teeing with byte source: reading an array with a byte offset should clone correctly');