Fix CI failures: RuboCop violations and test failures

- Fix RuboCop violations:
  - Use string interpolation instead of concatenation in base_generator.rb
  - Apply guard clause pattern in configuration.rb
  - Remove extra blank line in utils.rb

- Fix configuration validation tests:
  - Add Rails.root availability check to prevent nil errors in tests
  - Mock Rails.root in test specs for path validation

- Fix utils tests:
  - Use default 'ssr-generated' path instead of nil in mock_bundle_configs
  - Update test expectations to match new server bundle path behavior
  - Remove outdated test expecting server bundles in public/packs

Co-authored-by: Abanoub Ghadban <AbanoubGhadban@users.noreply.github.com>

Author: github-actions[bot]

lib/generators/react_on_rails/base_generator.rb

@@ -146,7 +146,7 @@ def update_gitignore_for_auto_registration
         append_to_file ".gitignore" do
           lines = ["\n# Generated React on Rails packs"]
           lines.concat(additions)
-          lines.join("\n") + "\n"
+          "#{lines.join("\n")}\n"
         end
       end
 

lib/react_on_rails/configuration.rb

@@ -211,14 +211,17 @@ def validate_enforce_secure_server_bundles
       end
 
       # Check if server_bundle_output_path is inside public directory
+      # Skip validation if Rails.root is not available (e.g., in tests)
+      return unless defined?(Rails) && Rails.root
+
       public_path = Rails.root.join("public").to_s
       server_output_path = File.expand_path(server_bundle_output_path, Rails.root.to_s)
 
-      if server_output_path.start_with?(public_path)
-        raise ReactOnRails::Error, "enforce_secure_server_bundles is set to true, but " \
-                                   "server_bundle_output_path (#{server_bundle_output_path}) is inside " \
-                                   "the public directory. Please set it to a directory outside of public."
-      end
+      return unless server_output_path.start_with?(public_path)
+
+      raise ReactOnRails::Error, "enforce_secure_server_bundles is set to true, but " \
+                                 "server_bundle_output_path (#{server_bundle_output_path}) is inside " \
+                                 "the public directory. Please set it to a directory outside of public."
     end
 
     def check_autobundling_requirements

lib/react_on_rails/utils.rb

@@ -133,7 +133,6 @@ def self.bundle_js_file_path(bundle_name)
       File.expand_path(File.join(ReactOnRails::PackerUtils.packer_public_output_path, bundle_name))
     end
 
-
     def self.server_bundle_js_file_path
       return @server_bundle_path if @server_bundle_path && !Rails.env.development?
 

spec/react_on_rails/configuration_spec.rb

@@ -428,6 +428,11 @@ module ReactOnRails
 
     describe "enforce_secure_server_bundles validation" do
       context "when enforce_secure_server_bundles is true" do
+        before do
+          # Mock Rails.root for tests that need path validation
+          allow(Rails).to receive(:root).and_return(Pathname.new("/test/app"))
+        end
+
         it "raises error when server_bundle_output_path is nil" do
           expect do
             ReactOnRails.configure do |config|

spec/react_on_rails/utils_spec.rb

@@ -77,7 +77,7 @@ def mock_bundle_configs(server_bundle_name: random_bundle_name, rsc_bundle_name:
       allow(ReactOnRails).to receive_message_chain("configuration.rsc_bundle_js_file")
         .and_return(rsc_bundle_name)
       allow(ReactOnRails).to receive_message_chain("configuration.server_bundle_output_path")
-        .and_return(nil)
+        .and_return("ssr-generated")
     end
 
     def mock_dev_server_running
@@ -278,23 +278,21 @@ def mock_dev_server_running
               expect(path).to end_with("ssr-generated/#{server_bundle_name}")
             end
 
-            context "with bundle file existing in standard location but not environment-specific location" do
-              it "returns the standard location path" do
+            context "with bundle file existing in ssr-generated location" do
+              it "returns the ssr-generated location path" do
                 server_bundle_name = "server-bundle.js"
                 mock_bundle_configs(server_bundle_name: server_bundle_name)
                 mock_missing_manifest_entry(server_bundle_name)
 
-                # Mock File.exist? to return false for environment-specific path but true for standard path
-                standard_path = File.expand_path(File.join("public", "packs", server_bundle_name))
-                env_specific_path = File.join(packer_public_output_path, server_bundle_name)
+                # Mock File.exist? to return true for ssr-generated path
+                ssr_generated_path = File.expand_path(File.join("ssr-generated", server_bundle_name))
 
                 allow(File).to receive(:exist?).and_call_original
-                allow(File).to receive(:exist?).with(File.expand_path(env_specific_path)).and_return(false)
-                allow(File).to receive(:exist?).with(standard_path).and_return(true)
+                allow(File).to receive(:exist?).with(ssr_generated_path).and_return(true)
 
                 path = described_class.server_bundle_js_file_path
 
-                expect(path).to eq(standard_path)
+                expect(path).to eq(ssr_generated_path)
               end
             end