Support multiple css paths

* Ensure only one css_path configuration is used
* Raise error if length of css_paths does not match routes
* Add comment in config file about css_paths

Author: randallreedjr

lib/config/critical_path_css.yml

@@ -3,6 +3,9 @@ defaults: &defaults
   manifest_name: application
   # Else provide the relative path of your CSS file from the /public directory
   # css_path: /path/to/css/from/public/main.css
+  # Or provide a separate path for each route
+  # css_paths:
+  #   - /path/to/css/from/public/main.css
   routes:
     - /
 

lib/critical_path_css/configuration.rb

@@ -13,6 +13,10 @@ def css_path
       @config['css_path']
     end
 
+    def css_paths
+      @config['css_paths']
+    end
+
     def manifest_name
       @config['manifest_name']
     end

lib/critical_path_css/css_fetcher.rb

@@ -10,7 +10,10 @@ def initialize(config)
     end
 
     def fetch
-      @config.routes.map { |route| [route, css_for_route(route)] }.to_h
+      @config.routes.map.with_index { |route, index|
+        css_path = @config.css_paths[index].present? ? @config.css_paths[index] : @config.css_path
+        [route, css_for_route(route, css_path)]
+      }.to_h
     end
 
     def fetch_route(route)
@@ -19,10 +22,10 @@ def fetch_route(route)
 
     protected
 
-    def css_for_route(route)
+    def css_for_route(route, css_path)
       options = {
         'url' => @config.base_url + route,
-        'css' => @config.css_path,
+        'css' => css_path,
         ## optional params
         # viewport dimensions
         'width' => 1300,

lib/critical_path_css/rails/config_loader.rb

@@ -5,12 +5,19 @@ class ConfigLoader
 
       def load
         config = YAML.safe_load(ERB.new(File.read(configuration_file_path)).result, [], [], true)[::Rails.env]
-        config['css_path'] = "#{::Rails.root}/public" + (
+        validate_css_path config
+        if config['css_path']
+          config['css_path'] = "#{::Rails.root}/public" + (
             config['css_path'] ||
               ActionController::Base.helpers.stylesheet_path(
                 config['manifest_name'], host: ''
               )
-        )
+          )
+          config['css_paths'] = []
+        else
+          config['css_path'] = ''
+          config['css_paths'] = config['css_paths'].collect { |path| "#{::Rails.root}/public#{path}" }
+        end
         config
       end
 
@@ -19,6 +26,14 @@ def load
       def configuration_file_path
         @configuration_file_path ||= ::Rails.root.join('config', CONFIGURATION_FILENAME)
       end
+
+      def validate_css_path(config)
+        if config['css_path'] && config['css_paths']
+          raise LoadError, 'Cannot specify both css_path and css_paths'
+        elsif config['css_paths'] && config['css_paths'].length != config['routes'].length
+          raise LoadError, 'Must specify css_paths for each route'
+        end
+      end
     end
   end
 end

lib/critical_path_css/rails/version.rb

@@ -1,5 +1,5 @@
 module CriticalPathCSS
   module Rails
-    VERSION = '2.6.0'.freeze
+    VERSION = '2.7.0'.freeze
   end
 end

spec/lib/critical_path_css/css_fetcher_spec.rb

@@ -0,0 +1,63 @@
+require 'spec_helper'
+
+RSpec.describe 'CssFetcher' do
+  describe '#fetch' do
+    let(:subject) { CriticalPathCss::CssFetcher.new(config) }
+    let(:response) {
+      ['foo','', OpenStruct.new(exitstatus: 0)]
+    }
+    let(:routes) { ['/', '/new_route'] }
+    let(:config) do
+      OpenStruct.new(
+        base_url: 'http://0.0.0.0:9292',
+        css_path: css_path,
+        css_paths: css_paths,
+        penthouse_options: {},
+        routes: routes
+      )
+    end
+
+    context 'when a single css_path is configured' do
+      let(:css_path) { '/test.css' }
+      let(:css_paths) { [] }
+
+      it 'generates css for each route from the same file' do
+        expect(Open3).to receive(:capture3) do |arg1, arg2, arg3|
+          options = JSON.parse(arg3)
+          expect(options['css']).to eq '/test.css'
+        end.twice.and_return(response)
+        subject.fetch
+      end
+    end
+
+    context 'when multiple css_paths are configured' do
+      let(:css_path) { '' }
+      let(:css_paths) { ['/test.css', '/test2.css'] }
+
+      it 'generates css for each route from the respective file' do
+        expect(Open3).to receive(:capture3) do |arg1, arg2, arg3|
+          options = JSON.parse(arg3)
+          expect(options['css']).to eq '/test.css' if options['url'] == 'http://0.0.0.0:9292/'
+          expect(options['css']).to eq '/test2.css' if options['url'] == 'http://0.0.0.0:9292/new_route'
+        end.twice.and_return(response)
+        subject.fetch
+      end
+    end
+
+    context 'when same css file applies to multiple routes' do
+      let(:css_path) { '' }
+      let(:css_paths) { ['/test.css', '/test2.css', '/test.css'] }
+      let(:routes) { ['/', '/new_route', '/newer_route'] }
+
+      it 'generates css for each route from the respective file' do
+        expect(Open3).to receive(:capture3) do |arg1, arg2, arg3|
+          options = JSON.parse(arg3)
+          expect(options['css']).to eq '/test.css' if options['url'] == 'http://0.0.0.0:9292/'
+          expect(options['css']).to eq '/test2.css' if options['url'] == 'http://0.0.0.0:9292/new_route'
+          expect(options['css']).to eq '/test.css' if options['url'] == 'http://0.0.0.0:9292/newer_route'
+        end.thrice.and_return(response)
+        subject.fetch
+      end
+    end
+  end
+end

spec/lib/critical_path_css/rails/config_loader_spec.rb

@@ -0,0 +1,125 @@
+require 'spec_helper'
+
+RSpec.describe 'ConfigLoader' do
+  let(:subject) { CriticalPathCss::Rails::ConfigLoader.new }
+  describe '#load' do
+    before do
+      allow(File).to receive(:read).and_return(config_file)
+    end
+
+    context 'when single css_path is specified' do
+      let(:config_file) {
+        <<~CONFIG
+          defaults: &defaults
+            base_url: http://0.0.0.0:9292
+            css_path: /test.css
+            routes:
+              - /
+
+          development:
+            <<: *defaults
+
+          test:
+            <<: *defaults
+        CONFIG
+      }
+
+      it 'sets css_path with the path' do
+        config = subject.load
+
+        expect(config['css_path']).to eq '/app/spec/internal/public/test.css'
+      end
+
+      it 'leaves css_paths empty' do
+        config = subject.load
+
+        expect(config['css_paths']).to eq []
+      end
+    end
+
+    context 'when multiple css_paths are specified' do
+      let(:config_file) {
+        <<~CONFIG
+          defaults: &defaults
+            base_url: http://0.0.0.0:9292
+            css_paths:
+              - /test.css
+              - /test2.css
+            routes:
+              - /
+              - /new_route
+
+          development:
+            <<: *defaults
+
+          test:
+            <<: *defaults
+        CONFIG
+      }
+
+      it 'sets css_path to empty string' do
+        config = subject.load
+
+        expect(config['css_path']).to eq ''
+      end
+
+      it 'leaves css_paths to an array of paths' do
+        config = subject.load
+
+        expect(config['css_paths']).to eq ['/app/spec/internal/public/test.css','/app/spec/internal/public/test2.css']
+      end
+    end
+
+    context 'when single css_path and multiple css_paths are both specified' do
+      let(:config_file) {
+        <<~CONFIG
+          defaults: &defaults
+            base_url: http://0.0.0.0:9292
+            css_path: /test.css
+            css_paths:
+              - /test.css
+              - /test2.css
+            routes:
+              - /
+              - /new_route
+
+          development:
+            <<: *defaults
+
+          test:
+            <<: *defaults
+        CONFIG
+      }
+
+      it 'raises an error' do
+        expect { subject.load }.to raise_error LoadError, 'Cannot specify both css_path and css_paths'
+      end
+    end
+
+    context 'when css_paths and routes are not the same length' do
+      let(:config_file) {
+        <<~CONFIG
+          defaults: &defaults
+            base_url: http://0.0.0.0:9292
+            css_paths:
+              - /test.css
+              - /test2.css
+            routes:
+              - /
+              - /new_route
+              - /newer_route
+
+          development:
+            <<: *defaults
+
+          test:
+            <<: *defaults
+        CONFIG
+      }
+
+      it 'raises an error' do
+        expect { subject.load }.to raise_error LoadError, 'Must specify css_paths for each route'
+      end
+    end
+  end
+end