This is consistent with the other 'micro' modules and allows implementing
additional features in Python via e.g. micropython-lib's sys.
Note this is a breaking change (not backwards compatible) for ports which
do not enable weak links, as "import sys" must now be replaced with
"import usys".
All imports are now tested to see if the test should be skipped,
UserFile.read is removed, and UserFile.readinto is made more efficient.
Signed-off-by: Damien George <damien@micropython.org>
These tests are specific to MicroPython so have a better home in the
micropython/ test subdir, and putting them here allows them to be run by
all targets, not just those that have access to the local filesystem (eg
the unix port).
Signed-off-by: Damien George <damien@micropython.org>