micropython-samples/uasyncio_iostream/tests

Tests for uasyncio iostream read/write changes

These tests perform concurrent input and output and use timers to emulate read/write hardware.
iotest1.py Device can perform unbuffered writes only.
iotest2.py Device performs buffered writes and unbuffered reads.
iotest4.py Run test(False) for unbuffered writes and buffered reads.
iotest5.py Unbuffered read and write.

Obsolete test:
iotest3.py Demonstrated workround for failing concurrent I/O using separate input and output objects.

Other tests:
iotest.py Measure timing of I/O scheduling with a scope.
auart.py Run a loopback test on a physical UART.
auart_hd.py Simulate a pair of devices running a half-duplex protocol over a pair of UARTs.

Note on I/O scheduling

Examination of the code, along with running iotest.py, demonstrates that I/O polling does not take place as frequently as it could. In the presence of coros which issue yield asyncio.sleep(0) polling occurs when all such coros have run.

An option is to modify core.py to schedule I/O after each coro has run - the drawback being a reduced rate at which these round-robin tasks are scheduled.