Rails configuration injection for specs

application.rb

# config/application.rb

module MyApp
  class Application < Rails::Application
    config.my_setting = "prod value"
  end
end

my_setting.rb

# spec/support/my_setting.rb

RSpec.configure do |config|
  config.around(:each) do |example|
    orig_my_setting = Rails.configuration.my_setting
    
    if example.metadata[:my_setting]
      Rails.configuration.my_setting = example.metadata[:my_setting]
    end
    
    example.run
    
    Rails.configuration.my_setting = orig_my_setting
  end
end

some_spec.rb

# spec/something/some_spec.rb

RSpec.describe "Example" do
  it "uses standard setting" do
    expect(Rails.configuration.my_setting).to eq("prod value")
  end
  
  it "overwrites the config", my_setting: "test value" do
    expect(Rails.configuration.my_setting).to eq("test value")
  end
end