refactor: Extract JS dependency management into shared module

Addresses code review feedback from PR #1788:

1. Created shared JsDependencyManager module to eliminate code duplication
   between base_generator.rb and install_generator.rb

2. Added comprehensive test coverage for:
   - Message deduplication (ensuring messages appear exactly once)
   - NPM install command deduplication
   - Proper module inclusion and method organization

3. Improved method organization in install_generator.rb

This refactoring follows DRY principles and makes the codebase more
maintainable by consolidating shared dependency management logic.

Co-authored-by: Justin Gordon <justin808@users.noreply.github.com>

Author: github-actions[bot]

lib/generators/react_on_rails/base_generator.rb

@@ -4,10 +4,12 @@
 require "fileutils"
 require_relative "generator_messages"
 require_relative "generator_helper"
+require_relative "js_dependency_manager"
 module ReactOnRails
   module Generators
     class BaseGenerator < Rails::Generators::Base
       include GeneratorHelper
+      include JsDependencyManager
 
       Rails::Generators.hide_namespace(namespace)
       source_root(File.expand_path("templates", __dir__))
@@ -95,6 +97,10 @@ def add_base_gems_to_gemfile
         run "bundle"
       end
 
+      def add_js_dependencies
+        setup_js_dependencies
+      end
+
       def update_gitignore_for_auto_registration
         gitignore_path = File.join(destination_root, ".gitignore")
         return unless File.exist?(gitignore_path)
@@ -134,123 +140,6 @@ def append_to_spec_rails_helper
 
       private
 
-      def setup_js_dependencies
-        add_js_dependencies
-        install_js_dependencies
-      end
-
-      def add_js_dependencies
-        add_react_on_rails_package
-        add_react_dependencies
-        add_css_dependencies
-        add_dev_dependencies
-      end
-
-      def add_react_on_rails_package
-        major_minor_patch_only = /\A\d+\.\d+\.\d+\z/
-
-        # Try to use package_json gem first, fall back to direct npm commands
-        react_on_rails_pkg = if ReactOnRails::VERSION.match?(major_minor_patch_only)
-                               ["react-on-rails@#{ReactOnRails::VERSION}"]
-                             else
-                               puts "Adding the latest react-on-rails NPM module. " \
-                                    "Double check this is correct in package.json"
-                               ["react-on-rails"]
-                             end
-
-        puts "Installing React on Rails package..."
-        return if add_npm_dependencies(react_on_rails_pkg)
-
-        puts "Using direct npm commands as fallback"
-        success = system("npm", "install", *react_on_rails_pkg)
-        handle_npm_failure("react-on-rails package", react_on_rails_pkg) unless success
-      end
-
-      def add_react_dependencies
-        puts "Installing React dependencies..."
-        react_deps = %w[
-          react
-          react-dom
-          @babel/preset-react
-          prop-types
-          babel-plugin-transform-react-remove-prop-types
-          babel-plugin-macros
-        ]
-        return if add_npm_dependencies(react_deps)
-
-        success = system("npm", "install", *react_deps)
-        handle_npm_failure("React dependencies", react_deps) unless success
-      end
-
-      def add_css_dependencies
-        puts "Installing CSS handling dependencies..."
-        css_deps = %w[
-          css-loader
-          css-minimizer-webpack-plugin
-          mini-css-extract-plugin
-          style-loader
-        ]
-        return if add_npm_dependencies(css_deps)
-
-        success = system("npm", "install", *css_deps)
-        handle_npm_failure("CSS dependencies", css_deps) unless success
-      end
-
-      def add_dev_dependencies
-        puts "Installing development dependencies..."
-        dev_deps = %w[
-          @pmmmwh/react-refresh-webpack-plugin
-          react-refresh
-        ]
-        return if add_npm_dependencies(dev_deps, dev: true)
-
-        success = system("npm", "install", "--save-dev", *dev_deps)
-        handle_npm_failure("development dependencies", dev_deps, dev: true) unless success
-      end
-
-      def install_js_dependencies
-        # Detect which package manager to use
-        success = if File.exist?(File.join(destination_root, "yarn.lock"))
-                    system("yarn", "install")
-                  elsif File.exist?(File.join(destination_root, "pnpm-lock.yaml"))
-                    system("pnpm", "install")
-                  elsif File.exist?(File.join(destination_root, "package-lock.json")) ||
-                        File.exist?(File.join(destination_root, "package.json"))
-                    # Use npm for package-lock.json or as default fallback
-                    system("npm", "install")
-                  else
-                    true # No package manager detected, skip
-                  end
-
-        unless success
-          GeneratorMessages.add_warning(<<~MSG.strip)
-            ⚠️  JavaScript dependencies installation failed.
-
-            This could be due to network issues or missing package manager.
-            You can install dependencies manually later by running:
-            • npm install (if using npm)
-            • yarn install (if using yarn)
-            • pnpm install (if using pnpm)
-          MSG
-        end
-
-        success
-      end
-
-      def handle_npm_failure(dependency_type, packages, dev: false)
-        install_command = dev ? "npm install --save-dev" : "npm install"
-        GeneratorMessages.add_warning(<<~MSG.strip)
-          ⚠️  Failed to install #{dependency_type}.
-
-          The following packages could not be installed automatically:
-          #{packages.map { |pkg| "  • #{pkg}" }.join("\n")}
-
-          This could be due to network issues or missing package manager.
-          You can install them manually later by running:
-            #{install_command} #{packages.join(' ')}
-        MSG
-      end
-
       def copy_webpack_main_config(base_path, config)
         webpack_config_path = "config/webpack/webpack.config.js"
 

lib/generators/react_on_rails/install_generator.rb

@@ -4,12 +4,14 @@
 require "json"
 require_relative "generator_helper"
 require_relative "generator_messages"
+require_relative "js_dependency_manager"
 
 module ReactOnRails
   module Generators
     # rubocop:disable Metrics/ClassLength
     class InstallGenerator < Rails::Generators::Base
       include GeneratorHelper
+      include JsDependencyManager
 
       # fetch USAGE file for details generator description
       source_root(File.expand_path(__dir__))
@@ -83,10 +85,7 @@ def invoke_generators
       end
 
       def setup_react_dependencies
-        @added_dependencies_to_package_json ||= false
-        @ran_direct_installs ||= false
-        add_js_dependencies
-        install_js_dependencies if @added_dependencies_to_package_json && !@ran_direct_installs
+        setup_js_dependencies
       end
 
       # NOTE: other requirements for existing files such as .gitignore or application.
@@ -346,11 +345,17 @@ def install_typescript_dependencies
         ]
 
         # Try using GeneratorHelper first (package manager agnostic)
-        return if add_npm_dependencies(typescript_packages, dev: true)
+        if add_npm_dependencies(typescript_packages, dev: true)
+          @added_dependencies_to_package_json = true
+          return
+        end
 
         # Fallback to npm if GeneratorHelper fails
         success = system("npm", "install", "--save-dev", *typescript_packages)
-        return if success
+        if success
+          @ran_direct_installs = true
+          return
+        end
 
         warning = <<~MSG.strip
           ⚠️  Failed to install TypeScript dependencies automatically.
@@ -420,134 +425,6 @@ def create_typescript_config
         puts Rainbow("✅ Created tsconfig.json").green
       end
 
-      def add_js_dependencies
-        add_react_on_rails_package
-        add_react_dependencies
-        add_css_dependencies
-        add_dev_dependencies
-      end
-
-      def add_react_on_rails_package
-        major_minor_patch_only = /\A\d+\.\d+\.\d+\z/
-
-        # Try to use package_json gem first, fall back to direct npm commands
-        react_on_rails_pkg = if ReactOnRails::VERSION.match?(major_minor_patch_only)
-                               ["react-on-rails@#{ReactOnRails::VERSION}"]
-                             else
-                               puts "Adding the latest react-on-rails NPM module. " \
-                                    "Double check this is correct in package.json"
-                               ["react-on-rails"]
-                             end
-
-        puts "Installing React on Rails package..."
-        if add_npm_dependencies(react_on_rails_pkg)
-          @added_dependencies_to_package_json = true
-          return
-        end
-
-        puts "Using direct npm commands as fallback"
-        success = system("npm", "install", *react_on_rails_pkg)
-        @ran_direct_installs = true if success
-        handle_npm_failure("react-on-rails package", react_on_rails_pkg) unless success
-      end
-
-      def add_react_dependencies
-        puts "Installing React dependencies..."
-        react_deps = %w[
-          react
-          react-dom
-          @babel/preset-react
-          prop-types
-          babel-plugin-transform-react-remove-prop-types
-          babel-plugin-macros
-        ]
-        if add_npm_dependencies(react_deps)
-          @added_dependencies_to_package_json = true
-          return
-        end
-
-        success = system("npm", "install", *react_deps)
-        @ran_direct_installs = true if success
-        handle_npm_failure("React dependencies", react_deps) unless success
-      end
-
-      def add_css_dependencies
-        puts "Installing CSS handling dependencies..."
-        css_deps = %w[
-          css-loader
-          css-minimizer-webpack-plugin
-          mini-css-extract-plugin
-          style-loader
-        ]
-        if add_npm_dependencies(css_deps)
-          @added_dependencies_to_package_json = true
-          return
-        end
-
-        success = system("npm", "install", *css_deps)
-        @ran_direct_installs = true if success
-        handle_npm_failure("CSS dependencies", css_deps) unless success
-      end
-
-      def add_dev_dependencies
-        puts "Installing development dependencies..."
-        dev_deps = %w[
-          @pmmmwh/react-refresh-webpack-plugin
-          react-refresh
-        ]
-        if add_npm_dependencies(dev_deps, dev: true)
-          @added_dependencies_to_package_json = true
-          return
-        end
-
-        success = system("npm", "install", "--save-dev", *dev_deps)
-        @ran_direct_installs = true if success
-        handle_npm_failure("development dependencies", dev_deps, dev: true) unless success
-      end
-
-      def install_js_dependencies
-        # Detect which package manager to use
-        success = if File.exist?(File.join(destination_root, "yarn.lock"))
-                    system("yarn", "install")
-                  elsif File.exist?(File.join(destination_root, "pnpm-lock.yaml"))
-                    system("pnpm", "install")
-                  elsif File.exist?(File.join(destination_root, "package-lock.json")) ||
-                        File.exist?(File.join(destination_root, "package.json"))
-                    # Use npm for package-lock.json or as default fallback
-                    system("npm", "install")
-                  else
-                    true # No package manager detected, skip
-                  end
-
-        unless success
-          GeneratorMessages.add_warning(<<~MSG.strip)
-            ⚠️  JavaScript dependencies installation failed.
-
-            This could be due to network issues or missing package manager.
-            You can install dependencies manually later by running:
-            • npm install (if using npm)
-            • yarn install (if using yarn)
-            • pnpm install (if using pnpm)
-          MSG
-        end
-
-        success
-      end
-
-      def handle_npm_failure(dependency_type, packages, dev: false)
-        install_command = dev ? "npm install --save-dev" : "npm install"
-        GeneratorMessages.add_warning(<<~MSG.strip)
-          ⚠️  Failed to install #{dependency_type}.
-
-          The following packages could not be installed automatically:
-          #{packages.map { |pkg| "  • #{pkg}" }.join("\n")}
-
-          This could be due to network issues or missing package manager.
-          You can install them manually later by running:
-            #{install_command} #{packages.join(' ')}
-        MSG
-      end
-
       # Removed: Shakapacker auto-installation logic (now explicit dependency)
 
       # Removed: Shakapacker 8+ is now required as explicit dependency