tests: test nitserial itself

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
tests: test a module generated by `nitserial`

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
tests: nitg-e doesn't know the full type of generics, expect the error

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>