Merge pull request #5 from RoleModel/add-app-json-generator

Include chrome buildpack in app_json

lib/generators/chromium/pdf/install/install_generator.rb

@@ -14,6 +14,43 @@ def create_pdf_job_templates
           copy_file 'app/jobs/generate_pdf_job.rb'
           copy_file 'config/initializers/good_job.rb'
         end
+
+        def include_chrome_buildpack_in_app_json
+          say(<<~SAY, :yellow)
+            N.B. app.json changes are only applied to new heroku apps.
+            In the case where your app already exists make sure to manually add the buildpack by running the command:
+            `heroku buildpacks:add heroku-community/chrome-for-testing`
+          SAY
+          add_buildpack_to_app_json
+        end
+
+        private
+
+        def add_buildpack_to_app_json
+          in_root do
+            update_json_file('app.json') do |data|
+              data['buildpacks'] << { 'url' => 'heroku-community/chrome-for-testing' }
+            end
+          end
+        end
+
+        def update_json_file(file_name)
+          data = if File.exist?(file_name)
+                   ActiveSupport::JSON.decode(File.read(file_name))
+                 else
+                   {}
+                 end
+          data['buildpacks'] ||= []
+
+          yield data
+
+          File.write(file_name, pretty_json(data))
+        end
+
+        def pretty_json(data)
+          require 'json'
+          JSON.pretty_generate(data)
+        end
       end
     end
   end

test/generators/install_generator_test.rb

@@ -7,7 +7,9 @@
 class InstallGeneratorTest < Rails::Generators::TestCase
   tests ::Chromium::Pdf::Generators::InstallGenerator
   destination File.expand_path('../../tmp', __dir__)
-  setup :prepare_destination
+  setup do
+    prepare_destination
+  end
 
   test 'pdf job template is created' do
     run_generator
@@ -18,4 +20,16 @@ class InstallGeneratorTest < Rails::Generators::TestCase
     run_generator
     assert_file 'config/initializers/good_job.rb'
   end
+
+  test 'app.json is created' do
+    @app_json_path = "#{destination_root}/app.json"
+
+    File.write(@app_json_path, ActiveSupport::JSON.encode({}))
+    run_generator
+    assert_includes(File.read(@app_json_path), 'heroku-community/chrome-for-testing')
+
+    File.write(@app_json_path, ActiveSupport::JSON.encode({ buildpacks: [] }))
+    run_generator
+    assert_includes(File.read(@app_json_path), 'heroku-community/chrome-for-testing')
+  end
 end