Tighten bundler config detection in system checker

Author: justin808

react_on_rails/lib/react_on_rails/system_checker.rb

@@ -11,6 +11,8 @@ module ReactOnRails
   class SystemChecker
     attr_reader :messages
 
+    SUPPORTED_ASSETS_BUNDLERS = %w[webpack rspack].freeze
+
     def initialize
       @messages = []
     end
@@ -134,7 +136,8 @@ def check_shakapacker_configuration
           • bin/shakapacker
           • bin/shakapacker-dev-server
           • config/shakapacker.yml
-          • config/{webpack,rspack}/{webpack,rspack}.config.{js,ts}
+          • config/webpack/webpack.config.{js,ts}
+          • config/rspack/rspack.config.{js,ts}
 
           Run: bundle exec rails shakapacker:install
         MSG
@@ -325,9 +328,9 @@ def detect_bundler_config_path
       end
 
       add_warning(
-        "⚠️  Found both webpack and rspack configs. Could not determine active bundler; defaulting to rspack."
+        "⚠️  Found both webpack and rspack configs. Could not determine active bundler; defaulting to webpack."
       )
-      paths_by_bundler["rspack"].first || paths_by_bundler["webpack"].first
+      paths_by_bundler["webpack"].first || paths_by_bundler["rspack"].first
     end
 
     def suggest_webpack_inspection(config_path)
@@ -519,16 +522,27 @@ def existing_bundler_config_paths(bundler)
     end
 
     def configured_assets_bundler
-      shakapacker_config_path = "config/shakapacker.yml"
-      return nil unless File.exist?(shakapacker_config_path)
+      config = parsed_shakapacker_config
+      return nil unless config
 
-      config_content = File.read(shakapacker_config_path)
-      match = config_content.match(/^\s*assets_bundler:\s*["']?(webpack|rspack)["']?\s*$/)
-      match&.captures&.first
-    rescue StandardError
+      rails_env = ENV["RAILS_ENV"] || ENV["RACK_ENV"] || "development"
+      bundler_from_shakapacker_section(config, rails_env) || bundler_from_shakapacker_section(config, "default")
+    rescue StandardError, ScriptError
       nil
     end
 
+    def bundler_from_shakapacker_section(config, section_name)
+      section = config[section_name] || config[section_name.to_sym]
+      return nil unless section.is_a?(Hash)
+
+      normalize_assets_bundler(section["assets_bundler"] || section[:assets_bundler])
+    end
+
+    def normalize_assets_bundler(value)
+      normalized = value.to_s.strip.downcase
+      SUPPORTED_ASSETS_BUNDLERS.include?(normalized) ? normalized : nil
+    end
+
     def required_react_dependencies
       deps = {
         "react" => "React library",

react_on_rails/spec/lib/react_on_rails/system_checker_spec.rb

@@ -154,6 +154,8 @@
         expect(result).to be false
         expect(checker.errors?).to be true
         expect(checker.messages.last[:content]).to include("Shakapacker is not properly configured")
+        expect(checker.messages.last[:content]).to include("config/webpack/webpack.config.{js,ts}")
+        expect(checker.messages.last[:content]).to include("config/rspack/rspack.config.{js,ts}")
       end
     end
 
@@ -716,13 +718,46 @@
         end).to be true
       end
 
-      it "warns and defaults to rspack when both bundlers exist and config is ambiguous" do
+      it "warns and defaults to webpack when both bundlers exist and config is ambiguous" do
         allow(File).to receive(:exist?).with("config/rspack/rspack.config.ts").and_return(true)
         allow(File).to receive(:exist?).with("config/webpack/webpack.config.ts").and_return(true)
         allow(File).to receive(:exist?).with("config/shakapacker.yml").and_return(false)
 
-        expect(checker.send(:detect_bundler_config_path)).to eq("config/rspack/rspack.config.ts")
-        expect(checker.messages.any? { |msg| msg[:content].include?("defaulting to rspack") }).to be true
+        expect(checker.send(:detect_bundler_config_path)).to eq("config/webpack/webpack.config.ts")
+        expect(checker.messages.any? { |msg| msg[:content].include?("defaulting to webpack") }).to be true
+      end
+    end
+
+    describe "#configured_assets_bundler" do
+      before do
+        allow(File).to receive(:exist?).with("config/shakapacker.yml").and_return(true)
+      end
+
+      it "parses ERB-backed assets_bundler values from shakapacker.yml" do
+        allow(File).to receive(:read).with("config/shakapacker.yml").and_return(<<~YAML)
+          default: &default
+            assets_bundler: <%= "webpack" %> # inline comment
+          development:
+            <<: *default
+        YAML
+
+        expect(checker.send(:configured_assets_bundler)).to eq("webpack")
+      end
+
+      it "prefers the current Rails environment over the default config" do
+        allow(File).to receive(:read).with("config/shakapacker.yml").and_return(<<~YAML)
+          default:
+            assets_bundler: webpack
+          test:
+            assets_bundler: rspack
+        YAML
+
+        original_rails_env = ENV.fetch("RAILS_ENV", nil)
+        ENV["RAILS_ENV"] = "test"
+
+        expect(checker.send(:configured_assets_bundler)).to eq("rspack")
+      ensure
+        ENV["RAILS_ENV"] = original_rails_env
       end
     end