Remove explicit Logger class verification

[bartekbsh]

This PR addresses problematic check in setter configuration that disallows using loggers that are not ruby ::Logger descendants. Current behavior not only doesn't allow using certain loggers (e.g. semantic_logger or logging) without dirty hacks, but also silently ignores setting value that does not match this validation.

I tried finding common behavior of more popular logging libraries to introduce idiomatic duck-typing instead of current class comparison, but there doesn't seem to be anything simple enough (apart from validating presence of all methods that dd-trace uses) -- commonly found methods #add and #log are not always present, and they are not always public.

I didn't find any test that would validate that only Logger descendants can be used, so I didn't introduce any changes to existing specs. Please let me know if you think, that's something worth verifying.

[marcotc]

👋 @bartekbsh, thank you very much for you contribution!
I think these changes do make sense: is_a?(::Logger) is too strict for sure.

We have some test around this logic here:

dd-trace-rb/spec/ddtrace/configuration/settings_spec.rb

Lines 282 to 314 in 5bd0dba

	describe '#logger' do
	describe '#instance' do
	subject(:instance) { settings.logger.instance }
	it { is_expected.to be nil }
	end
	describe '#instance=' do
	let(:logger) { Datadog::Logger.new(STDOUT) }
	it 'updates the #instance setting' do
	expect { settings.logger.instance = logger }
	.to change { settings.logger.instance }
	.from(nil)
	.to(logger)
	end
	end
	describe '#level' do
	subject(:level) { settings.logger.level }
	it { is_expected.to be ::Logger::INFO }
	end
	describe 'level=' do
	let(:level) { ::Logger::DEBUG }
	it 'changes the #statsd setting' do
	expect { settings.logger.level = level }
	.to change { settings.logger.level }
	.from(::Logger::INFO)
	.to(level)
	end
	end
	end

Would you mind adding tests that covers the ability to set any arbitrary object as a logger?

[bartekbsh]

Hey @marcotc! I'll add the test later today.

[bartekbsh]

I have decided to use double with logger-like interface in spec.

[marcotc]

Thank you for you contribution @bartekbsh! 🎉

[ericmustin]

👋 @bartekbsh This has been released in 0.41.0 https://github.com/DataDog/dd-trace-rb/releases/tag/v0.41.0, thanks again for the contribution!