Fix byte behavior

[kenji-miyake]

Public API Changes

None.

Description

Split from #646.

Fixed the behavior around bytes.

How to test

Before(upstream/ros2)

$ # Terminal 1
$ ros2 run rosbridge_server rosbridge_websocket
[ERROR 1632497492.739524112] [rosbridge_websocket]: [Client 0] [id: publish:/byte:3] publish: example_interfaces/Byte message requires a octet for field data, but got a <class 'int'>
[ERROR 1632497493.727461853] [rosbridge_websocket]: [Client 0] [id: publish:/byte:4] publish: example_interfaces/Byte message requires a octet for field data, but got a <class 'int'>

$ # Terminal 2
$ curl -sL https://github.com/tier4/rosbridge_suite/raw/add-test-scripts/test_scripts/byte.py | python
publish: {'data': 1}
publish: {'data': 1}

After(this PR)

$ # Terminal 1
$ ros2 run rosbridge_server rosbridge_websocket

$ # Terminal 2
$ curl -sL https://github.com/tier4/rosbridge_suite/raw/add-test-scripts/test_scripts/byte.py | python
publish: {'data': 1}
subscribe: {'data': 1}
publish: {'data': 1}
subscribe: {'data': 1}

[jtbandes]

Thanks for the fixes!

I think it would be nice to add an integration test to cover these features. Recently I refactored these tests so it's easy to make an end-to-end test using the @websocket_test decorator, where you can send/receive messages across the websocket and set up rclpy publishers/subscribers in the same test code. We could add a test which shows that it's possible to send/receive std_msgs/Byte as JSON.

[kenji-miyake]

Thank you for the information, I'll consider that!