56789);  // Super-precise offsets should round-trip.

                  // Append first part of media segment.
                  test.expectEvent(sourceBuffer, 'updateend', 'Partial media segment append ended.');
                  sourceBuffer.appendBuffer(partialMediaSegment);
              });

              test.waitForExpectedEvents(function()
              {
                  assert_false(sourceBuffer.updating, 'updating attribute is false');
                  assert_equals(sourceBuffer.mode, 'segments