Merge branch 'jejacks0n/tooling/improve-gitlab-experiment-deprecation-handling' into 'master'

Improve how we handle deprecation warnings

See merge request gitlab-org/gitlab!79994

config/initializers/gitlab_experiment.rb

 # frozen_string_literal: true
 
-module Gitlab
-  class Experiment
-    class Configuration
-      def self.deprecated(*args, version:, stack: 0)
-        # do nothing here
-      end
-    end
-  end
-end
-
 Gitlab::Experiment.configure do |config|
   # The base experiment class that will be instantiated when using the
   # `experiment` DSL, is our ApplicationExperiment. If a custom experiment
@@ -81,4 +71,31 @@ Gitlab::Experiment.configure do |config|
       )
     ))
   end
+
+  # Deprecation warnings resolution for 0.7.0
+  #
+  # We're working through deprecation warnings one by one in:
+  # https://gitlab.com/gitlab-org/gitlab/-/issues/350944
+  #
+  config.singleton_class.prepend(Module.new do
+    # Disable all deprecations in non dev/test environments.
+    #
+    def deprecated(*args, version:, stack: 0)
+      super if Gitlab.dev_or_test_env?
+    end
+
+    # Maintain a list of resolved deprecations to ensure that no new uses appear.
+    #
+    # Once a resolved deprecation warning has been added here, any future use will
+    # raise an exception.
+    #
+    ActiveSupport::Deprecation.disallowed_warnings += [
+      # 'Gitlab::Experiment 0.8 (instead use `control`)', # don't use `use`
+      # 'Gitlab::Experiment 0.8 (instead use `candidate`)', # don't use `try`
+      # 'Gitlab::Experiment 0.8 (instead use `variant(:variant_name)`)', # don't use `try(:variant_name)`
+      # 'Gitlab::Experiment 0.8 (instead use `assigned(:candidate)`)', # don't use variant(:variant_name) to assign
+      # 'Gitlab::Experiment 0.8 (instead use `assigned`)', # don't use variant.name to get the assigned variant
+      # 'Gitlab::Experiment 0.8, instead register variants using:', # don't use public `*_behavior` methods
+    ]
+  end)
 end

spec/experiments/application_experiment_spec.rb

@@ -391,4 +391,29 @@ RSpec.describe ApplicationExperiment, :experiment do
       end
     end
   end
+
+  context "with deprecation warnings" do
+    before do
+      Gitlab::Experiment::Configuration.instance_variable_set(:@__dep_versions, nil) # clear the internal memoization
+
+      allow(ActiveSupport::Deprecation).to receive(:new).and_call_original
+    end
+
+    it "doesn't warn on non dev/test environments" do
+      allow(Gitlab).to receive(:dev_or_test_env?).and_return(false)
+
+      expect { experiment(:example) { |e| e.use { } } }.not_to raise_error
+      expect(ActiveSupport::Deprecation).not_to have_received(:new).with(anything, 'Gitlab::Experiment')
+    end
+
+    it "warns on dev and test environments" do
+      allow(Gitlab).to receive(:dev_or_test_env?).and_return(true)
+
+      # This will eventually raise an ActiveSupport::Deprecation exception,
+      # it's ok to change it when that happens.
+      expect { experiment(:example) { |e| e.use { } } }.not_to raise_error
+
+      expect(ActiveSupport::Deprecation).to have_received(:new).with(anything, 'Gitlab::Experiment')
+    end
+  end
 end

spec/support/gitlab_experiment.rb

@@ -26,7 +26,3 @@ RSpec.configure do |config|
     stub_snowplow
   end
 end
-
-# Once you've resolved a given deprecation, you can disallow it here, which
-# will raise an exception if it's used anywhere.
-ActiveSupport::Deprecation.disallowed_warnings << "`experiment_group?` is deprecated"