Raise on deprecation when SOLIDUS_RAISE_DEPRECATIONS set

core/lib/spree/testing_support/dummy_app.rb

@@ -41,6 +41,12 @@ def self.setup(gem_root:, lib_name:, auto_migrate: true)
     DummyApp::Application.config.root = root
     DummyApp::Application.initialize! unless DummyApp::Application.initialized?
 
+    # Raise on deprecation warnings.
+    # NOTE: This needs to happen after the application is initialized.
+    if ENV['SOLIDUS_RAISE_DEPRECATIONS'].present?
+      Spree.deprecator.behavior = :raise
+    end
+
     if auto_migrate
       DummyApp::Migrations.auto_migrate
     end
@@ -151,8 +157,3 @@ class Application < ::Rails::Application
     config.taxon_attachment_module = 'Spree::Taxon::PaperclipAttachment'
   end
 end
-
-# Raise on deprecation warnings
-if ENV['SOLIDUS_RAISE_DEPRECATIONS'].present?
-  Spree.deprecator.behavior = :raise
-end

core/spec/lib/spree/deprecator_spec.rb

@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe "Spree.deprecator" do
+  Dummy = Class.new do
+    def deprecated_method
+      "foo"
+    end
+    deprecate :deprecated_method, deprecator: Spree.deprecator
+  end
+
+  context "by default" do
+    it "returns a valid deprecator" do
+      expect(Spree.deprecator).to have_attributes(
+        deprecation_horizon: "5.0",
+        gem_name: "Solidus"
+      )
+    end
+
+    it "does not raise an error unless overridden by environment" do
+      if ENV["SOLIDUS_RAISE_DEPRECATIONS"]
+        expect { Dummy.new.deprecated_method }.to raise_error(ActiveSupport::DeprecationException)
+      else
+        expect { Dummy.new.deprecated_method }.not_to raise_error
+      end
+    end
+  end
+
+  context "when the behavior has been changed to :raise" do
+    around do |example|
+      behavior_name = ActiveSupport::Deprecation::DEFAULT_BEHAVIORS.detect { |_behavior_name, behavior_proc|
+        behavior_proc == Spree.deprecator.behavior.first
+      }.first
+
+      Spree.deprecator.behavior = :raise
+
+      example.run
+
+      Spree.deprecator.behavior = behavior_name
+    end
+
+    it "raises an error when a deprecated method is called" do
+      expect { Dummy.new.deprecated_method }
+        .to raise_error(ActiveSupport::DeprecationException)
+    end
+  end
+end