Allow fetching all references for a file, or all files, using public API

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

@@ -0,0 +1,45 @@
+# typed: strict
+# frozen_string_literal: true
+
+module Packwerk
+  # 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
+    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).flat_map { |file| list(file) }
+    end
+
+    sig { params(relative_file: String).returns(T::Array[Packwerk::Reference]) }
+    def list(relative_file)
+      references_result = @run_context.references_from_file(relative_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

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) }

test/unit/packwerk/references_from_file_test.rb

@@ -0,0 +1,59 @@
+# typed: true
+# frozen_string_literal: true
+
+require "test_helper"
+
+module Packwerk
+  class ReferencesFromFileTest < Minitest::Test
+    setup do
+      config = Configuration.new
+      config.stubs(:load_paths).returns({})
+      @run_context = RunContext.from_configuration(config)
+      RunContext.stubs(:from_configuration).with(config).returns(@run_context)
+      @referencer = ReferencesFromFile.new(config)
+    end
+
+    test "raises on parser error" do
+      offense = Offense.new(file: "something.rb", message: "yo")
+      @run_context.stubs(:references_from_file).returns(
+        RunContext::FileReferencesResult.new(file_offenses: [offense], references: [])
+      )
+
+      assert_raises ReferencesFromFile::FileParserError do
+        @referencer.list("lib/something.rb")
+      end
+    end
+
+    test "fetches violations for all files from run context" do
+      references = {
+        "lib/something.rb" => [
+          make_fake_reference,
+        ],
+        "components/ice_cream_sales/app/models/scoop.rb" => [
+          make_fake_reference,
+        ],
+      }
+      @referencer.stubs(:files).returns(references.keys)
+
+      references.each do |file, references|
+        @run_context.stubs(:references_from_file).with(relative_file: file).returns(
+          RunContext::FileReferencesResult.new(file_offenses: [], references: references)
+        )
+      end
+
+      assert_equal Set.new(references.values.flatten), Set.new(@referencer.list_all)
+    end
+
+    private
+
+    def make_fake_reference
+      package_name = Array("ilikeletters".chars.sample(5)).join
+      Reference.new(
+        package: Package.new(name: package_name),
+        relative_path: package_name,
+        constant: ConstantContext.new,
+        source_location: nil
+      )
+    end
+  end
+end