Implement author-constructible ReadableStream using V8 extras

third_party/WebKit/LayoutTests/http/tests/streams/resources/rs-test-templates.js

+'use strict';
+
+// These tests can be run against any readable stream produced by the web platform that meets the given descriptions.
+// For readable stream tests, the factory should return the stream. For reader tests, the factory should return a
+// { stream, reader } object. (You can use this to vary the time at which you acquire a reader.)
+
+self.templatedRSEmpty = function (label, factory) {
+    test(function() {
+    }, 'Running templatedRSEmpty with ' + label);
+
+    test(function() {
+        var rs = factory();
+
+        assert_equals(typeof rs.locked, 'boolean', 'has a boolean locked getter');
+        assert_equals(typeof rs.cancel, 'function', 'has a cancel method');
+        assert_equals(typeof rs.getReader, 'function', 'has a getReader method');
+        assert_equals(typeof rs.tee, 'function', 'has a tee method');
+    }, 'instances have the correct methods and properties');
+};
+
+self.templatedRSClosed = function (label, factory) {
+    test(function() {
+    }, 'Running templatedRSClosed with ' + label);
+
+    var test1 = async_test('cancel() should return a distinct fulfilled promise each time');
+    test1.step(function() {
+        var rs = factory();
+        var promisesCount = 0;
+        var allChecked = false;
+
+        var cancelPromise1 = rs.cancel();
+        var cancelPromise2 = rs.cancel();
+
+        cancelPromise1.then(test1.step_func(function(v) {
+            assert_equals(v, undefined, 'first cancel() call should fulfill with undefined');
+            ++promisesCount;
+        }));
+        cancelPromise2.then(test1.step_func(function(v) {
+            assert_equals(v, undefined, 'second cancel() call should fulfill with undefined');
+            assert_equals(++promisesCount, 2);
+            assert_true(allChecked);
+            test1.done();
+        }));
+        assert_not_equals(cancelPromise1, cancelPromise2, 'cancel() calls should return distinct promises');
+        allChecked = true;
+    });
+
+    test(function() {
+        var rs = factory();
+
+        assert_false(rs.locked, 'locked getter should return false');
+    }, 'locked should be false');
+
+    test(function() {
+        var rs = factory();
+
+        rs.getReader(); // getReader() should not throw.
+    }, 'getReader() should be OK');
+
+    test(function() {
+        var rs = factory();
+
+        var reader = rs.getReader();
+        reader.releaseLock();
+
+        reader = rs.getReader(); // Getting a second reader should not throw.
+        reader.releaseLock();
+
+        rs.getReader(); // Getting a third reader should not throw.
+    }, 'should be able to acquire multiple readers if they are released in succession');
+
+    test(function() {
+        var rs = factory();
+
+        rs.getReader();
+
+        assert_throws(new TypeError(), function() { rs.getReader(); }, 'getting a second reader should throw');
+        assert_throws(new TypeError(), function() { rs.getReader(); }, 'getting a third reader should throw');
+    }, 'should not be able to acquire a second reader if we don\'t release the first one');
+};
+
+self.templatedRSErrored = function (label, factory, error) {
+    test(function() {
+    }, 'Running templatedRSErrored with ' + label);
+
+    var test2 = async_test('getReader() should return a reader that acts errored');
+    test2.step(function() {
+        var rs = factory();
+        var promisesCount = 0;
+
+        var reader = rs.getReader();
+
+        reader.closed.catch(test2.step_func(function(e) {
+            assert_equals(e, error, 'reader.closed should reject with the error');
+            if (++promisesCount === 2)
+                test2.done();
+        }));
+        reader.read().catch(test2.step_func(function(e) {
+            assert_equals(e, error, 'reader.read() should reject with the error');
+            if (++promisesCount === 2)
+                test2.done();
+        }));
+    });
+
+    var test3 = async_test('read() twice should give the error each time');
+    test3.step(function() {
+        var rs = factory();
+        var promiseCount = 0;
+
+        var reader = rs.getReader();
+
+        reader.read().catch(test3.step_func(function(e) {
+            assert_equals(e, error, 'reader.read() should reject with the error');
+            assert_equals(++promiseCount, 1);
+        }));
+        reader.read().catch(test3.step_func(function(e) {
+            assert_equals(e, error, 'reader.read() should reject with the error');
+            assert_equals(++promiseCount, 2);
+        }));
+        reader.closed.catch(test3.step_func(function(e) {
+            assert_equals(e, error, 'reader.closed should reject with the error');
+            assert_equals(++promiseCount, 3);
+            test3.done();
+        }));
+   });
+
+    test(function() {
+        var rs = factory();
+
+        assert_false(rs.locked, 'locked getter should return false');
+    }, 'locked should be false');
+};
+
+self.templatedRSErroredSyncOnly = function (label, factory, error) {
+    test(function() {
+    }, 'Running templatedRSErroredSyncOnly with ' + label);
+
+    var test1 = async_test('should be able to obtain a second reader, with the correct closed promise');
+    test1.step(function() {
+        var rs = factory();
+
+        rs.getReader().releaseLock();
+
+        var reader = rs.getReader(); // Calling getReader() twice does not throw (the stream is not locked).
+
+        reader.closed.then(
+            test1.step_func(function() { assert_unreached('closed promise should not be fulfilled when stream is errored'); }),
+            test1.step_func(function(err) {
+                assert_equals(err, error);
+                test1.done();
+            })
+        );
+    });
+
+    test(function() {
+        var rs = factory();
+
+        rs.getReader();
+
+        assert_throws(new TypeError(), function() { rs.getReader(); }, 'getting a second reader should throw a TypeError');
+        assert_throws(new TypeError(), function() { rs.getReader(); }, 'getting a third reader should throw a TypeError');
+    }, 'should not be able to obtain additional readers if we don\'t release the first lock');
+
+    var test2 = async_test('cancel() should return a distinct rejected promise each time');
+    test2.step(function() {
+        var rs = factory();
+        var promisesCount = 0;
+        var allChecked = false;
+
+        var cancelPromise1 = rs.cancel();
+        var cancelPromise2 = rs.cancel();
+
+        cancelPromise1.catch(test2.step_func(function(e) {
+            assert_equals(e, error, 'first cancel() call should reject with the error');
+            ++promisesCount;
+        }));
+        cancelPromise2.catch(test2.step_func(function(e) {
+            assert_equals(e, error, 'second cancel() call should reject with the error');
+            assert_equals(++promisesCount, 2);
+            assert_true(allChecked);
+            test2.done();
+        }));
+        assert_not_equals(cancelPromise1, cancelPromise2, 'cancel() calls should return distinct promises');
+        allChecked = true;
+    });
+
+    var test3 = async_test('reader cancel() should return a distinct rejected promise each time');
+    test3.step(function() {
+        var rs = factory();
+        var reader = rs.getReader();
+        var promisesCount = 0;
+        var allChecked = false;
+
+        var cancelPromise1 = reader.cancel();
+        var cancelPromise2 = reader.cancel();
+
+        cancelPromise1.catch(test3.step_func(function(e) {
+            assert_equals(e, error, 'first cancel() call should reject with the error');
+            ++promisesCount;
+        }));
+        cancelPromise2.catch(test3.step_func(function(e) {
+            assert_equals(e, error, 'second cancel() call should reject with the error');
+            assert_equals(++promisesCount, 2);
+            assert_true(allChecked);
+            test3.done();
+        }));
+        assert_not_equals(cancelPromise1, cancelPromise2, 'cancel() calls should return distinct promises');
+        allChecked = true;
+    });
+};
+
+self.templatedRSEmptyReader = function (label, factory) {
+    test(function() {
+    }, 'Running templatedRSEmptyReader with ' + label);
+
+    test(function() {
+        var reader = factory().reader;
+
+        assert_true('closed' in reader, 'has a closed property');
+        assert_equals(typeof reader.closed.then, 'function', 'closed property is thenable');
+
+        assert_equals(typeof reader.cancel, 'function', 'has a cancel method');
+        assert_equals(typeof reader.read, 'function', 'has a read method');
+        assert_equals(typeof reader.releaseLock, 'function', 'has a releaseLock method');
+    }, 'instances have the correct methods and properties');
+
+    test(function() {
+        var stream = factory().stream;
+
+        assert_true(stream.locked, 'locked getter should return true');
+    }, 'locked should be true');
+
+    var test1 = async_test('read() should never settle');
+    test1.step(function() {
+        var reader = factory().reader;
+
+        reader.read().then(
+            test1.step_func(function() { assert_unreached('read() should not fulfill'); }),
+            test1.step_func(function() { assert_unreached('read() should not reject'); })
+        );
+
+        setTimeout(test1.step_func(function() { test1.done(); }), 1000);
+    });
+
+    var test2 = async_test('two read()s should both never settle');
+    test2.step(function() {
+        var reader = factory().reader;
+
+        reader.read().then(
+            test2.step_func(function() { assert_unreached('first read() should not fulfill'); }),
+            test2.step_func(function() { assert_unreached('first read() should not reject'); })
+        );
+
+        reader.read().then(
+            test2.step_func(function() { assert_unreached('second read() should not fulfill'); }),
+            test2.step_func(function() { assert_unreached('second read() should not reject'); })
+        );
+
+        setTimeout(test2.step_func(function() { test2.done(); }), 1000);
+    });
+
+    test(function() {
+        var reader = factory().reader;
+
+        assert_not_equals(reader.read(), reader.read(), 'the promises returned should be distinct');
+    }, 'read() should return distinct promises each time');
+
+    test(function() {
+        var stream = factory().stream;
+
+        assert_throws(new TypeError(), function() { stream.getReader(); }, 'stream.getReader() should throw a TypeError');
+    }, 'getReader() again on the stream should fail');
+
+    var test3 = async_test('releasing the lock with pending read requests should throw but the read requests should stay pending');
+    test3.step(function() {
+        var streamAndReader = factory();
+        var stream = streamAndReader.stream;
+        var reader = streamAndReader.reader;
+
+        reader.read().then(
+            test3.step_func(function() { assert_unreached('first read() should not fulfill'); }),
+            test3.step_func(function() { assert_unreached('first read() should not reject'); })
+        );
+
+        reader.read().then(
+            test3.step_func(function() { assert_unreached('second read() should not fulfill'); }),
+            test3.step_func(function() { assert_unreached('second read() should not reject'); })
+        );
+
+        reader.closed.then(
+            test3.step_func(function() { assert_unreached('closed should not fulfill'); }),
+            test3.step_func(function() { assert_unreached('closed should not reject'); })
+        );
+
+        assert_throws(new TypeError(), function() { reader.releaseLock(); }, 'releaseLock should throw a TypeError');
+
+        assert_true(stream.locked, 'the stream should still be locked');
+
+        setTimeout(test3.step_func(function() { test3.done(); }), 1000);
+    });
+
+    var test4 = async_test('releasing the lock should cause further read() calls to reject with a TypeError', { timeout: 50 });
+    test4.step(function() {
+        var promiseCalls = 0;
+        var reader = factory().reader;
+
+        reader.releaseLock();
+
+        reader.read().catch(test4.step_func(function(e) {
+            assert_throws(new TypeError(), function() { throw e; }, 'first read() should reject with a TypeError');
+            assert_equals(++promiseCalls, 1);
+        }));
+        reader.read().catch(test4.step_func(function(e) {
+            assert_throws(new TypeError(), function() { throw e; }, 'second read() should reject with a TypeError');
+            assert_equals(++promiseCalls, 2);
+            test4.done();
+        }));
+    });
+
+    var test5 = async_test('releasing the lock should cause closed to reject', { timeout: 50 });
+    test5.step(function() {
+        var reader = factory().reader;
+
+        var closedBefore = reader.closed;
+        reader.releaseLock();
+        var closedAfter = reader.closed;
+
+        assert_equals(closedBefore, closedAfter, 'the closed promise should not change identity')
+        closedBefore.catch(test5.step_func(function(e) {
+            assert_throws(new TypeError(), function() { throw e; }, 'reader.closed should reject with a TypeError');
+            test5.done();
+        }));
+    });
+
+    test(function() {
+        var streamAndReader = factory();
+        var stream = streamAndReader.stream;
+        var reader = streamAndReader.reader;
+
+        reader.releaseLock();
+        assert_false(stream.locked, 'locked getter should return false');
+    }, 'releasing the lock should cause locked to become false');
+
+    var test6 = async_test('canceling via the reader should cause the reader to act closed');
+    test6.step(function() {
+        var reader = factory().reader;
+
+        reader.cancel();
+        reader.read().then(test6.step_func(function(r) {
+            assert_object_equals(r, { value: undefined, done: true }, 'read()ing from the reader should give a done result');
+            test6.done();
+        }));
+    });
+
+    var test7 = async_test('canceling via the stream should fail');
+    test7.step(function() {
+        var stream = factory().stream;
+
+        stream.cancel().catch(test7.step_func(function(e) {
+            assert_throws(new TypeError(), function() { throw e; }, 'cancel() should reject with a TypeError');
+            test7.done();
+        }));
+    });
+};
+
+self.templatedRSClosedReader = function (label, factory) {
+    test(function() {
+    }, 'Running templatedRSClosedReader with ' + label);
+
+    var  test1 = async_test('read() should fulfill with { value: undefined, done: true }');
+    test1.step(function() {
+        var reader = factory().reader;
+
+        reader.read().then(
+            test1.step_func(function(v) {
+                assert_object_equals(v, { value: undefined, done: true }, 'read() should fulfill correctly');
+                test1.done();
+            }),
+            test1.step_func(function() { assert_unreached('read() should not return a rejected promise'); })
+        );
+    });
+
+    var test2 = async_test('read() multiple times should fulfill with { value: undefined, done: true }');
+    test2.step(function() {
+        var reader = factory().reader;
+        var readCount = 0;
+
+        reader.read().then(
+            test2.step_func(function(v) {
+                assert_object_equals(v, { value: undefined, done: true }, 'read() should fulfill correctly');
+                ++readCount;
+            }),
+            test2.step_func(function() { assert_unreached('read() should not return a rejected promise'); })
+        );
+        reader.read().then(
+            test2.step_func(function(v) {
+                assert_object_equals(v, { value: undefined, done: true }, 'read() should fulfill correctly');
+                assert_equals(++readCount, 2);
+                test2.done();
+            }),
+            test2.step_func(function() { assert_unreached('read() should not return a rejected promise'); })
+        );
+    });
+
+    var test3 = async_test('read() should work when used within another read() fulfill callback');
+    test3.step(function() {
+        var reader = factory().reader;
+
+        reader.read().then(test3.step_func(function() { reader.read().then(test3.step_func(function() { test3.done('read() should fulfill'); })); }));
+    });
+
+    var test4 = async_test('closed should fulfill with undefined');
+    test4.step(function() {
+        var reader = factory().reader;
+
+        reader.closed.then(
+            test4.step_func(function(v) {
+                assert_equals(v, undefined, 'reader closed should fulfill with undefined');
+                test4.done();
+            }),
+            test4.step_func(function() { assert_unreached('reader closed should not reject'); })
+        );
+    });
+
+    var test5 = async_test('releasing the lock should cause closed to reject and change identity');
+    test5.step(function() {
+        var promiseCalls = 0;
+        var reader = factory().reader;
+
+        var closedBefore = reader.closed;
+        reader.releaseLock();
+        var closedAfter = reader.closed;
+
+        assert_not_equals(closedBefore, closedAfter, 'the closed promise should change identity')
+        closedBefore.then(test5.step_func(function(v) {
+            assert_equals(v, undefined, 'reader.closed acquired before release should fulfill');
+            assert_equals(++promiseCalls, 1);
+        }));
+        closedAfter.catch(test5.step_func(function(e) {
+            assert_throws(new TypeError(), function() { throw e; }, 'reader.closed acquired after release should reject with a TypeError');
+            assert_equals(++promiseCalls, 2);
+            test5.done();
+        }));
+    });
+
+    var test6 = async_test('cancel() should return a distinct fulfilled promise each time');
+    test6.step(function() {
+        var reader = factory().reader;
+        var promiseCount = 0;
+        var allChecked = false;
+
+        var cancelPromise1 = reader.cancel();
+        var cancelPromise2 = reader.cancel();
+        var closedReaderPromise = reader.closed;
+
+        cancelPromise1.then(test6.step_func(function(v) {
+            assert_equals(v, undefined, 'first cancel() call should fulfill with undefined');
+            ++promiseCount;
+        }));
+        cancelPromise2.then(test6.step_func(function(v) {
+            assert_equals(v, undefined, 'second cancel() call should fulfill with undefined');
+            assert_equals(++promiseCount, 2);
+            assert_true(allChecked);
+            test6.done();
+        }));
+        assert_not_equals(cancelPromise1, cancelPromise2, 'cancel() calls should return distinct promises');
+        assert_not_equals(cancelPromise1, closedReaderPromise, 'cancel() promise 1 should be distinct from reader.closed');
+        assert_not_equals(cancelPromise2, closedReaderPromise, 'cancel() promise 2 should be distinct from reader.closed');
+        allChecked = true;
+    });
+};
+
+self.templatedRSErroredReader = function (label, factory, error) {
+    test(function() {
+    }, 'Running templatedRSErroredReader with ' + label);
+
+    var test1 = async_test('closed should reject with the error');
+    test1.step(function() {
+        var reader = factory().reader;
+
+        reader.closed.then(
+            test1.step_func(function() { assert_unreached('stream closed should not fulfill'); }),
+            test1.step_func(function(r) {
+                assert_equals(r, error, 'stream closed should reject with the error');
+                test1.done();
+            })
+        );
+    });
+
+    var test2 = async_test('releasing the lock should cause closed to reject and change identity');
+    test2.step(function() {
+        var reader = factory().reader;
+
+        var closedBefore = reader.closed;
+
+        closedBefore.catch(test2.step_func(function(e) {
+            assert_equals(e, error, 'reader.closed acquired before release should reject with the error');
+
+            reader.releaseLock();
+            var closedAfter = reader.closed;
+
+            assert_not_equals(closedBefore, closedAfter, 'the closed promise should change identity');
+
+            return closedAfter.catch(test2.step_func(function(e) {
+                assert_throws(new TypeError(), function() { throw e; }, 'reader.closed acquired after release should reject with a TypeError');
+                test2.done();
+            }));
+        })).catch(test2.step_func(function(e) { assert_unreached(e); }));
+    });
+
+    var test3 = async_test('read() should reject with the error');
+    test3.step(function() {
+        var reader = factory().reader;
+
+        reader.read().then(
+            test3.step_func(function() {
+                assert_unreached('read() should not fulfill');
+            }),
+            test3.step_func(function(r) {
+                assert_equals(r, error, 'read() should reject with the error');
+                test3.done();
+            })
+        );
+    });
+};
+
+self.templatedRSTwoChunksOpenReader = function (label, factory, chunks) {
+    test(function() {
+    }, 'Running templatedRSTwoChunksOpenReader with ' + label);
+
+    var test1 = async_test('calling read() twice without waiting will eventually give both chunks');
+    test1.step(function() {
+        var reader = factory().reader;
+        var promiseCount = 0;
+
+        reader.read().then(test1.step_func(function(r) {
+            assert_object_equals(r, { value: chunks[0], done: false }, 'first result should be correct');
+            ++promiseCount;
+        }));
+        reader.read().then(test1.step_func(function(r) {
+            assert_object_equals(r, { value: chunks[1], done: false }, 'second result should be correct');
+            assert_equals(++promiseCount, 2);
+            test1.done();
+        }));
+    });
+
+    var test2 = async_test('calling read() twice with waiting will eventually give both chunks');
+    test2.step(function() {
+        var reader = factory().reader;
+
+        reader.read().then(test2.step_func(function(r) {
+            assert_object_equals(r, { value: chunks[0], done: false }, 'first result should be correct');
+
+            return reader.read().then(test2.step_func(function(r) {
+                assert_object_equals(r, { value: chunks[1], done: false }, 'second result should be correct');
+                test2.done();
+            }));
+        })).catch(test2.step_func(function(e) { assert_unreached(e); }));
+    });
+
+    test(function() {
+        var reader = factory().reader;
+
+        assert_not_equals(reader.read(), reader.read(), 'the promises returned should be distinct');
+    }, 'read() should return distinct promises each time');
+
+    var test3 = async_test('cancel() after a read() should still give that single read result');
+    test3.step(function() {
+        var reader = factory().reader;
+        var promiseCount = 0;
+
+        reader.closed.then(test3.step_func(function(v) {
+            assert_equals(v, undefined, 'reader closed should fulfill with undefined');
+            ++promiseCount;
+        }));
+
+        reader.read().then(test3.step_func(function(r) {
+            assert_object_equals(r, { value: chunks[0], done: false }, 'promise returned before cancellation should fulfill with a chunk');
+            ++promiseCount;
+        }));
+
+        reader.cancel();
+
+        reader.read().then(test3.step_func(function(r) {
+            assert_object_equals(r, { value: undefined, done: true }, 'promise returned after cancellation should fulfill with an end-of-stream signal');
+            assert_equals(++promiseCount, 3);
+            test3.done();
+        }))
+    });
+};
+
+self.templatedRSTwoChunksClosedReader = function (label, factory, chunks) {
+    test(function() {
+    }, 'Running templatedRSTwoChunksClosedReader with ' + label);
+
+    var test1 = async_test('third read(), without waiting, should give { value: undefined, done: true }');
+    test1.step(function() {
+        var reader = factory().reader;
+        var promiseCount = 0;
+
+        reader.read().then(test1.step_func(function(r) {
+            assert_object_equals(r, { value: chunks[0], done: false }, 'first result should be correct');
+            ++promiseCount;
+        }));
+        reader.read().then(test1.step_func(function(r) {
+            assert_object_equals(r, { value: chunks[1], done: false }, 'second result should be correct');
+            ++promiseCount;
+        }));
+        reader.read().then(test1.step_func(function(r) {
+            assert_object_equals(r, { value: undefined, done: true }, 'third result should be correct');
+            assert_equals(++promiseCount, 3);
+            test1.done();
+        }))
+    });
+
+    var test2 = async_test('third read, with waiting, should give { value: undefined, done: true }');
+    test2.step(function() {
+        var reader = factory().reader;
+
+        reader.read().then(test2.step_func(function(r) {
+            assert_object_equals(r, { value: chunks[0], done: false }, 'first result should be correct');
+
+            return reader.read().then(test2.step_func(function(r) {
+                assert_object_equals(r, { value: chunks[1], done: false }, 'second result should be correct');
+
+                return reader.read().then(test2.step_func(function(r) {
+                    assert_object_equals(r, { value: undefined, done: true }, 'third result should be correct');
+                    test2.done();
+                }));
+            }));
+        })).catch(test2.step_func(function(e) { assert_unreached(e); }));
+    });
+
+    var test3 = async_test('draining the stream via read() should cause the reader closed promise to fulfill, but locked stays true');
+    test3.step(function() {
+        var streamAndReader = factory();
+        var stream = streamAndReader.stream;
+        var reader = streamAndReader.reader;
+
+        assert_true(stream.locked, 'stream should start locked');
+
+        reader.closed.then(
+            test3.step_func(function(v) {
+                assert_equals(v, undefined, 'reader closed should fulfill with undefined');
+                assert_true(stream.locked, 'stream should remain locked');
+                test3.done();
+            }),
+            test3.step_func(function() { assert_unreached('reader closed should not reject'); })
+        );
+
+        reader.read();
+        reader.read();
+    });
+
+    var test4 = async_test('releasing the lock after the stream is closed should cause locked to become false');
+    test4.step(function() {
+        var streamAndReader = factory();
+        var stream = streamAndReader.stream;
+        var reader = streamAndReader.reader;
+
+        reader.closed.then(test4.step_func(function() {
+            assert_true(stream.locked, 'the stream should start locked');
+            reader.releaseLock(); // Releasing the lock after reader closed should not throw.
+            assert_false(stream.locked, 'the stream should end unlocked');
+            test4.done();
+        }));
+
+        reader.read();
+        reader.read();
+    });
+
+    var test5 = async_test('releasing the lock should cause further read() calls to reject with a TypeError', { timeout: 50});
+    test5.step(function() {
+        var promiseCalls = 0;
+        var reader = factory().reader;
+
+        reader.releaseLock();
+
+        reader.read().catch(test5.step_func(function(e) {
+            assert_throws(new TypeError(), function() { throw e; }, 'first read() should reject with a TypeError');
+            assert_equals(++promiseCalls, 1);
+        }));
+        reader.read().catch(test5.step_func(function(e) {
+            assert_throws(new TypeError(), function() { throw e; }, 'second read() should reject with a TypeError');
+            assert_equals(++promiseCalls, 2);
+        }));
+        reader.read().catch(test5.step_func(function(e) {
+            assert_throws(new TypeError(), function() { throw e; }, 'third read() should reject with a TypeError');
+            assert_equals(++promiseCalls, 3);
+            test5.done();
+        }));
+    });
+
+    var test6 = async_test('reader\'s closed property always returns the same promise');
+    test6.step(function() {
+        var streamAndReader = factory();
+        var stream = streamAndReader.stream;
+        var reader = streamAndReader.reader;
+
+        var readerClosed = reader.closed;
+
+        assert_equals(reader.closed, readerClosed, 'accessing reader.closed twice in succession gives the same value');
+
+        reader.read().then(test6.step_func(function() {
+            assert_equals(reader.closed, readerClosed, 'reader.closed is the same after read() fulfills');
+
+            reader.releaseLock();
+
+            assert_equals(reader.closed, readerClosed, 'reader.closed is the same after releasing the lock');
+
+            var newReader = stream.getReader();
+            newReader.read();
+
+            test6.done();
+        }));
+
+        assert_equals(reader.closed, readerClosed, 'reader.closed is the same after calling read()');
+    });
+};