cozy-logger: should we refactor cozy-logger?

[Ldoppea]

Current cozy-logger implementation may be troublesome for future maintainers. Here are some questions/remarks I had in my head when reading the code:

• filterOut() method's name is suggesting that it's filtering something, but it just returns a boolean. Then the caller decides to filter it or not regarding the boolean.
• filterOut() implementation is suggesting that all filters should return a boolean, but filterSecrets() can only return void or throw an exception.
  • I'm not sure it is a good thing to throw an exception from a logger (imho loggers should never impact an app's behavior). Are we sure we want this?
• What is the secret log level for? It is not documented, and filters prevent it to be called. Is it used somewhere?
• filters logic is inverted compared to filterOut
  • if filterOut returns true : object should be filtered
  • If a filter (filterLevel) returns true : object should NOT be filtered
• filterLevel() always return false if the given type does not exist in the levels array. This is intended but I think we should make this behavior more visible (even if this creates redundant code)
• setNoRetry() seems not to be used (except from unit tests). Is it dead code?
• To few unit tests are written for this regarding the number of possible combinations

What do you think about this?

I would suggest to refactor this code, but as it is used in a lot of places and as it is stable code (not edited during last 3 years) this choice may be discutable.

[trollepierre]

Moreover I think the log method has 4 required parameters, but we notice 2 to 3 parameters filled for most of its usage. I suggest to make explicit the required parameters, document their use with JSDoc, and add one example in the README

And I don't see the minilog website working but it got mention in our documentation: https://docs.cozy.io/en/cozy-client/logging/ .