I'm confronted to a huge "spaghetti code" with known lack of documentation, lack of test covering, high complexity, lack of design rules to be follow, etc. I let the code be analysed by a default sonar-scan, and surprisingly for me, the maintability has a really great score with a technical debt of 1,1% ! Reality shows that almost each change introduce new bugs
I'm quite perplex, and wonder if some particularities in the implementation could explain this score... We have for example quite a lot of interfaces (feeling 4-5 Interfaces for 1 implementation), uses reflexion and service locator pattern.
Are there other indicator that I could use that would be eventually more relevant for improving the quality?