Database classes: cover roundtrip fbs+cbor and copy fbs+cbor

[oberstet]

actually, to fully cover the complete interface the database table classes expose, the 2 test functions we currently have per database table are not enough, but we additionally need

• roundtrip cbor
• roundtrip fbs
• copy cbor to fbs
• copy fbs to cbor

like for example here https://github.com/crossbario/cfxdb/blob/master/cfxdb/tests/test_user.py

[oberstet]

note that while all DB classes already have a marshal function (and this function is indeed used in eg the xbrnetwork backend or the market maker), this is not covered by tests, and eg inconsistent types had been a practical headache already

also note, the User.parse class function, which is lacking from most of the other DB classes, but should be there, because it is the "inverse" of marshal

[om26er]

So it seems all our current tests are centered around the fbs variants of things (apart from the tests you linked above) because our database schema classes are from flatbuffers. We'd first need to write schema classes that are cbor-able.

@oberstet do we need to do that now ?

[oberstet]

do we need to do that now ?

all our DB classes need to have "marshal" and "parse", so yes, adding those is part A of this issue. part B is then adding the tests using the new functions (and the existings fbs ones) ..