[core] remove Monkey module

[delner]

Removing the legacy Monkey module in favor of a new API.

[p-lambert]

🎉 🎉 🎉

Only thing worth noting here is that we're no longer testing for "idempotency", which might be a useful property of our patchers. This, however, should be now part of the unit tests of each integration. (maybe a shared example for the tests written in RSpec?)

Also worth double checking if we have a test case for Configuration#use asserting that:

Datadog.configure do |c|
  c.use :foo
end

Calls patch on :foo.

[delner]

Shared example for RSpecs as we convert contribs over would make sense. (Means now that we have RSpec, we'd only have to code the test case once, too!)

I can look at the Configuration unit tests to see it has that example. I suspect the code itself is fine (since replacing Monkey.patch_module for configure :use allowed tests to pass), but wouldn't hurt to have the little extra coverage if we don't already.

[delner]

@p-lambert It looks like there's already a test for Configuration#use:

  def test_use_method
      contrib = Minitest::Mock.new
      contrib.expect(:patch, true)
      contrib.expect(:sorted_options, [])

      @registry.add(:example, contrib)
      @configuration.use(:example)

      assert_mock(contrib)
    end

See

dd-trace-rb/test/configuration_test.rb

Line 12 in a3ba36f

def test_use_method

Does that address all your blocking feedback?

[palazzem]

if @p-lambert comment is already addressed, I'm good with this change that removes a legacy API that is not used. We're losing the patch_all method (that wasn't working for some integrations), but the explicit approach is way better. We may think to reintroduce it if required in another PR.