Use Shakapacker gem API for server bundle path detection

- Replace manual YAML parsing with proper Shakapacker.config API calls
- Use Shakapacker.config.source_path and Shakapacker.config.source_entry_path
- Gracefully fallback to defaults when Shakapacker gem is not available
- Ensures accurate path detection that respects all Shakapacker configuration

This fixes the issue where doctor was checking app/javascript/packs/server-bundle.js
instead of the correct client/app/packs/server-bundle.js path from shakapacker.yml.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: justin808

lib/react_on_rails/doctor.rb

@@ -247,34 +247,21 @@ def print_recommendations
     end
 
     def determine_server_bundle_path
-      # Try to read Shakapacker configuration
-      shakapacker_config = read_shakapacker_config
-      if shakapacker_config
-        source_path = shakapacker_config["source_path"] || "app/javascript"
-        source_entry_path = shakapacker_config["source_entry_path"] || "packs"
+      # Try to use Shakapacker gem API to get configuration
+      begin
+        require "shakapacker"
+        source_path = Shakapacker.config.source_path
+        source_entry_path = Shakapacker.config.source_entry_path
         server_bundle_filename = get_server_bundle_filename
 
         File.join(source_path, source_entry_path, server_bundle_filename)
-      else
-        # Fallback to default paths
+      rescue LoadError, NameError, StandardError
+        # Fallback to default paths if Shakapacker is not available or configured
         server_bundle_filename = get_server_bundle_filename
         "app/javascript/packs/#{server_bundle_filename}"
       end
     end
 
-    def read_shakapacker_config
-      config_path = "config/shakapacker.yml"
-      return nil unless File.exist?(config_path)
-
-      begin
-        require "yaml"
-        config = YAML.load_file(config_path)
-        config["default"] || config
-      rescue StandardError
-        nil
-      end
-    end
-
     def get_server_bundle_filename
       # Try to read from React on Rails initializer
       initializer_path = "config/initializers/react_on_rails.rb"

spec/lib/react_on_rails/doctor_spec.rb

@@ -29,7 +29,6 @@
 
       # Mock the new server bundle path methods
       allow(doctor).to receive(:determine_server_bundle_path).and_return("app/javascript/packs/server-bundle.js")
-      allow(doctor).to receive(:read_shakapacker_config).and_return(nil)
       allow(doctor).to receive(:get_server_bundle_filename).and_return("server-bundle.js")
 
       # Mock the checker to avoid actual system calls
@@ -83,28 +82,25 @@
     let(:doctor) { described_class.new }
 
     describe "#determine_server_bundle_path" do
-      context "when shakapacker.yml exists" do
-        let(:shakapacker_config) do
-          {
-            "source_path" => "client/app",
-            "source_entry_path" => "packs"
-          }
-        end
+      context "when Shakapacker gem is available" do
+        let(:shakapacker_config) { double(source_path: "client/app", source_entry_path: "packs") }
 
         before do
-          allow(doctor).to receive(:read_shakapacker_config).and_return(shakapacker_config)
+          shakapacker_module = double("Shakapacker", config: shakapacker_config)
+          stub_const("Shakapacker", shakapacker_module)
+          allow(doctor).to receive(:require).with("shakapacker").and_return(true)
           allow(doctor).to receive(:get_server_bundle_filename).and_return("server-bundle.js")
         end
 
-        it "uses shakapacker configuration" do
+        it "uses Shakapacker API configuration" do
           path = doctor.send(:determine_server_bundle_path)
           expect(path).to eq("client/app/packs/server-bundle.js")
         end
       end
 
-      context "when shakapacker.yml does not exist" do
+      context "when Shakapacker gem is not available" do
         before do
-          allow(doctor).to receive(:read_shakapacker_config).and_return(nil)
+          allow(doctor).to receive(:require).with("shakapacker").and_raise(LoadError)
           allow(doctor).to receive(:get_server_bundle_filename).and_return("server-bundle.js")
         end