DEV: Custom generator for rename site setting migration (#24841)

Ability to automatically generate migration when site setting name is changed.
Example usage: `rails generate site_setting_rename_migration site_description contact_email`

lib/generators/site_setting_rename_migration/USAGE

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+Description:
+    Generates migration to rename a site setting name from an old name to a new site setting name. This assumes that the new setting is the same data format as the old one.
+
+Example:
+    bin/rails generate site_setting_rename_migration old_setting_name new_setting_name
+
+    This will create:
+        db/migrate/20231212111111_rename_old_setting_name_setting.rb

lib/generators/site_setting_rename_migration/site_setting_rename_migration_generator.rb

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+# frozen_string_literal: true
+
+class SiteSettingRenameMigrationGenerator < Rails::Generators::Base
+  argument :old_name, type: :string, banner: "old setting name", required: true
+  argument :new_name, type: :string, banner: "new setting name", required: true
+
+  def create_migration_file
+    timestamp = Time.zone.now.to_s.tr("^0-9", "")[0..13]
+    file_path = "db/migrate/#{timestamp}_rename_#{old_name}_setting.rb"
+    class_name = "Rename#{old_name.classify}Setting"
+
+    validate_setting_name!(old_name)
+    validate_setting_name!(new_name)
+
+    create_file file_path, <<~MIGRATION_FILE
+      # frozen_string_literal: true
+
+      class #{class_name} < ActiveRecord::Migration[7.0]
+        def up
+          execute "UPDATE site_settings SET name = '#{new_name}' WHERE name = '#{old_name}'"
+        end
+
+        def down
+          execute "UPDATE site_settings SET name = '#{old_name}' WHERE name = '#{new_name}'"
+        end
+      end
+    MIGRATION_FILE
+  end
+
+  private
+
+  def validate_setting_name!(name)
+    begin
+      SiteSetting.send(name)
+    rescue NoMethodError
+      say "Site setting with #{name} does not exist"
+      raise ArgumentError
+    end
+  end
+end

spec/generator/site_setting_rename_migrations_generator_spec.rb

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+# frozen_string_literal: true
+
+require "rails_helper"
+require "rails/generators"
+require "generators/site_setting_rename_migration/site_setting_rename_migration_generator"
+
+RSpec.describe SiteSettingRenameMigrationGenerator, type: :generator do
+  it "generates the correct migration" do
+    freeze_time DateTime.parse("2010-01-01 12:00")
+    described_class.start(%w[site_description contact_email], destination_root: "#{Rails.root}/tmp")
+    file_path = "#{Rails.root}/tmp/db/migrate/20100101120000_rename_site_description_setting.rb"
+
+    expected_content = <<~EXPECTED_CONTENT
+      # frozen_string_literal: true
+
+      class RenameSiteDescriptionSetting < ActiveRecord::Migration[7.0]
+        def up
+          execute "UPDATE site_settings SET name = 'contact_email' WHERE name = 'site_description'"
+        end
+
+        def down
+          execute "UPDATE site_settings SET name = 'site_description' WHERE name = 'contact_email'"
+        end
+      end
+    EXPECTED_CONTENT
+
+    expect(File.read(file_path)).to eq(expected_content)
+    File.delete(file_path)
+  end
+
+  it "raises an error when old name is incorrect" do
+    expect { described_class.start(%w[wrong_name contact_email]) }.to raise_error(ArgumentError)
+  end
+
+  it "raises an error when new name is incorrect" do
+    expect { described_class.start(%w[site_description wrong_name]) }.to raise_error(ArgumentError)
+  end
+end