pipeline mocking incompatible with ng-pipeline

[colinsurprenant]

For example the input method at

logstash-devutils/lib/logstash/devutils/rspec/logstash_helpers.rb

Lines 68 to 76 in 15c59bf

	pipeline.instance_eval do
	# create closure to capture queue
	@output_func = lambda { |event| queue << event }
	# output_func is now a method, call closure
	def output_func(event)
	@output_func.call(event)
	end
	end

is very implementation specific and does not work in ng-pipeline.

/cc @andrewvc

[colinsurprenant]

We will have to release a new version on the plugin tied to the new version on logstash with ng-pipeline.