Improve coverage

[leducp]

related to #201

[github-actions]

File	Coverage	Lines	Branches
All files	86%	87%	85%	✅
lib/include/kickcat/Error.h	87%	92%	83%	✅
lib/include/kickcat/SBufQueue.h	80%	98%	63%	✅
lib/master/include/kickcat/Bus.h	71%	100%	42%	❌
lib/master/src/Bus.cc	83%	85%	81%	✅
lib/master/src/CoE.cc	85%	93%	77%	✅
lib/master/src/Link.cc	98%	100%	97%	✅
lib/master/src/Prints.cc	99%	99%	100%	✅
lib/slave/src/AbstractESC.cc	90%	100%	81%	✅
lib/slave/src/AbstractEmulatedEEPROM.cc	0%	0%	0%	❌
lib/slave/src/ESMStates.cc	94%	99%	89%	✅
lib/slave/src/ESM.cc	92%	93%	90%	✅
lib/slave/src/PDO.cc	86%	92%	80%	✅
lib/slave/src/EEPROM/EEPROM_factory.cc	0%	0%	100%	❌
lib/slave/src/ESC/EmulatedESC.cc	53%	60%	46%	❌
lib/slave/src/slave/Slave.cc	94%	88%	100%	✅
lib/src/Frame.cc	87%	92%	82%	✅
lib/src/Mailbox.cc	69%	76%	62%	❌
lib/src/SIIParser.cc	93%	95%	91%	✅
lib/src/protocol.cc	99%	98%	100%	✅
lib/src/CoE/EsiParser.cc	90%	93%	87%	✅
lib/src/CoE/OD.cc	99%	99%	100%	✅
lib/src/CoE/mailbox/request.cc	82%	86%	77%	✅
lib/src/CoE/mailbox/response.cc	93%	97%	88%	✅

Minimum allowed coverage is 75%

Generated by 🐒 cobertura-action against aa30ed4

[trns1997]

hmmm i do not get the tests, they work but i feel like they don't test much, maybe we should add a counter example (maybe in an other PR) where we show the slave ends up in a problem state, to cover all branches

[leducp]

agree
Put it in draft for the moment