proposed cleaner solution

lib/packwerk.rb

@@ -32,6 +32,7 @@ module Packwerk
   autoload :Reference
   autoload :ReferenceOffense
   autoload :Validator
+  autoload :ReferencesFromFile
 
   module OutputStyles
     extend ActiveSupport::Autoload

lib/packwerk/references_from_file.rb

@@ -1,35 +1,45 @@
-# typed: false
+# typed: strict
 # frozen_string_literal: true
 
 module Packwerk
-    # Extracts all static constant references between Ruby files.
-    # Reuses the packwerk configuration.
-    # Hackishly hooks into packwerk internals.
-    class ReferencesFromFile
-      def initialize(config = Configuration.from_path)
-        @config = config
-        # RunContext is a `private_constant` of `Packwerk`
-        @run_context = RunContext.from_configuration(@config)
-      end
-
-      def list_all(relative_file_paths: [])
-        # FilesForProcessing is a `private_constant` of `Packwerk`
-        files = FilesForProcessing.fetch(relative_file_paths:, configuration: @config).files
-
-        files.map { |file| list(file) }.flatten(1)
+  # Extracts all static constant references between Ruby files.
+  class ReferencesFromFile
+    extend T::Sig
+
+    class FileParserError < RuntimeError
+      extend T::Sig
+
+      sig { params(file: String, offenses: T::Array[Packwerk::Offense]).void }
+      def initialize(file:, offenses:)
+        super("Errors while parsing #{file}: #{offenses.map(&:to_s).join("\n")}")
       end
-
-      def list(relative_file)
-        file_processor = @run_context.send(:file_processor)
-        context_provider = @run_context.send(:context_provider)
-
-        unresolved_references = file_processor.call(relative_file).unresolved_references
-
-        # ReferenceExtractor is a `private_constant` of `Packwerk`
-        ReferenceExtractor.get_fully_qualified_references_from(
-          unresolved_references,
-          context_provider
-        )
+    end
+
+    sig { params(config: Packwerk::Configuration).void }
+    def initialize(config = Configuration.from_path)
+      @config = config
+      @run_context = T.let(RunContext.from_configuration(@config), RunContext)
+    end
+
+    sig { params(relative_file_paths: T::Array[String]).returns(T::Array[Packwerk::Reference]) }
+    def list_all(relative_file_paths: [])
+      files(relative_file_paths: relative_file_paths).map { |file| list(file) }.flatten(1)
+    end
+
+    sig { params(relative_file: String).returns(T::Array[Packwerk::Reference]) }
+    def list(relative_file)
+      references_result = @run_context.references_from_file(relative_file:)
+
+      if references_result.file_offenses.present?
+        raise FileParserError.new(file: relative_file, offenses: references_result.file_offenses)
       end
+
+      references_result.references
+    end
+
+    sig { params(relative_file_paths: T::Array[String]).returns(T::Set[String]) }
+    def files(relative_file_paths: [])
+      FilesForProcessing.fetch(relative_file_paths: relative_file_paths, configuration: @config).files
     end
-  end
+  end
+end

lib/packwerk/run_context.rb

@@ -75,15 +75,29 @@ def initialize(
 
     sig { params(relative_file: String).returns(T::Array[Packwerk::Offense]) }
     def process_file(relative_file:)
+      reference_checker = ReferenceChecking::ReferenceChecker.new(@checkers)
+
+      references_result = references_from_file(relative_file: relative_file)
+
+      references_result.file_offenses +
+        references_result.references.flat_map { |reference| reference_checker.call(reference) }
+    end
+
+    class FileReferencesResult < T::Struct
+      const :references, T::Array[Packwerk::Reference]
+      const :file_offenses, T::Array[Packwerk::Offense]
+    end
+
+    sig { params(relative_file: String).returns(FileReferencesResult) }
+    def references_from_file(relative_file:)
       processed_file = file_processor.call(relative_file)
 
       references = ReferenceExtractor.get_fully_qualified_references_from(
         processed_file.unresolved_references,
         context_provider
       )
-      reference_checker = ReferenceChecking::ReferenceChecker.new(@checkers)
 
-      processed_file.offenses + references.flat_map { |reference| reference_checker.call(reference) }
+      FileReferencesResult.new(references: references, file_offenses: processed_file.offenses)
     end
 
     sig { returns(PackageSet) }