Fix Theme Check to be resilient when it's running offline without bundled resources (#734)

Author: karreiro

lib/theme_check/shopify_liquid/source_index.rb

@@ -56,6 +56,9 @@ def deprecated_filters
 
         def load_file(file_name)
           read_json(local_path!(file_name))
+        rescue StandardError
+          # If files get manually deleted, fallback with an empty list.
+          []
         end
 
         def local_path!(file_name)

lib/theme_check/shopify_liquid/source_manager.rb

@@ -9,6 +9,8 @@ module ShopifyLiquid
     class SourceManager
       REQUIRED_FILE_NAMES = [:filters, :objects, :tags, :latest].freeze
 
+      class DownloadResourceError < StandardError; end
+
       class << self
         def download_or_refresh_files(destination = default_destination)
           if has_required_files?(destination)
@@ -24,6 +26,9 @@ def download(destination = default_destination)
           REQUIRED_FILE_NAMES.each do |file_name|
             download_file(local_path(file_name, destination), remote_path(file_name))
           end
+        rescue DownloadResourceError
+          # If a request error occurs, ignore it. This ensures that Theme Check
+          # can rely on the sources included during the bundling phase.
         end
 
         def refresh(destination = default_destination)
@@ -73,8 +78,8 @@ def remote_path(file_name)
         end
 
         def download_file(local_path, remote_uri)
+          content = open_uri(remote_uri)
           File.open(local_path, "wb") do |file|
-            content = open_uri(remote_uri)
             file.write(content)
           end
         end
@@ -104,6 +109,8 @@ def open_uri(uri_str)
           end
 
           res.body
+        rescue StandardError
+          raise DownloadResourceError
         end
       end
     end

test/shopify_liquid/source_manager_test.rb

@@ -42,7 +42,18 @@ def test_download_creates_directory
 
         download_or_refresh_files
 
-        assert_test_documentation_up_to_date(tmp_dir)
+      ensure
+        FileUtils.remove_entry(@tmp_dir)
+      end
+
+      def test_download_when_a_request_error_happens
+        tmp_dir = Pathname.new("#{@tmp_dir}/new")
+
+        @source_manager_class.stubs(:open_uri).raises(SourceManager::DownloadResourceError)
+        @source_manager_class.stubs(:default_destination).returns(tmp_dir)
+
+        # Nothing is raised
+        download_or_refresh_files
       ensure
         FileUtils.remove_entry(@tmp_dir)
       end