Implement configurable formatter

lib/packwerk/cli.rb

@@ -33,7 +33,7 @@ def initialize(
       @configuration = T.let(configuration || Configuration.from_path, Configuration)
       @progress_formatter = T.let(Formatters::ProgressFormatter.new(@out, style: style), Formatters::ProgressFormatter)
       @offenses_formatter = T.let(
-        offenses_formatter || Formatters::OffensesFormatter.new(style: @style),
+        offenses_formatter || Configuration.offenses_formatter || Formatters::OffensesFormatter.new(style: @style),
         OffensesFormatter
       )
     end

lib/packwerk/configuration.rb

@@ -7,6 +7,8 @@
 module Packwerk
   class Configuration
     class << self
+      extend T::Sig
+
       def from_path(path = Dir.pwd)
         raise ArgumentError, "#{File.expand_path(path)} does not exist" unless File.exist?(path)
 
@@ -19,6 +21,9 @@ def from_path(path = Dir.pwd)
         end
       end
 
+      sig { returns(T.nilable(OffensesFormatter)) }
+      attr_accessor :offenses_formatter
+
       private
 
       def from_packwerk_config(path)

test/fixtures/extended/config/my_local_extension.rb

@@ -1,2 +1,16 @@
 module MyLocalExtension
 end
+
+class MyOffensesFormatter
+  include Packwerk::OffensesFormatter
+
+  def show_offenses(offenses)
+    ["hi i am a custom offense formatter", *offenses].join("\n")
+  end
+
+  def show_stale_violations(_offense_collection, _fileset)
+    "stale violations report"
+  end
+end
+
+Packwerk::Configuration.offenses_formatter = MyOffensesFormatter.new

test/support/application_fixture_helper.rb

@@ -13,6 +13,11 @@ def setup_application_fixture
     @old_working_dir = Dir.pwd
   end
 
+  def remove_extensions
+    Object.send(:remove_const, :MyLocalExtension) if defined?(MyLocalExtension)
+    Packwerk::Configuration.offenses_formatter = nil
+  end
+
   def teardown_application_fixture
     Dir.chdir(@old_working_dir)
     FileUtils.remove_entry(@app_dir, true) if using_template?

test/unit/cli_test.rb

@@ -17,6 +17,7 @@ class CliTest < Minitest::Test
 
     teardown do
       teardown_application_fixture
+      remove_extensions
     end
 
     test "#execute_command with the subcommand check starts processing files" do
@@ -168,5 +169,37 @@ def show_stale_violations(_offense_collection, _fileset)
 
       refute success
     end
+
+    test "#execute_command using a custom offenses class loaded in via packwerk.yml" do
+      use_template(:extended)
+
+      file_path = "path/of/exile.rb"
+      violation_message = "This is a violation of code health."
+      offense = Offense.new(file: file_path, message: violation_message)
+
+      RunContext.any_instance.stubs(:process_file)
+        .returns([offense])
+
+      cli = nil
+      string_io = StringIO.new
+      mock_require_method = ->(required_thing) do
+        next unless required_thing.include?("my_local_extension")
+
+        require required_thing
+      end
+      ExtensionLoader.stub(:require, mock_require_method) do
+        cli = ::Packwerk::Cli.new(out: string_io)
+      end
+
+      ::Packwerk::FilesForProcessing.stubs(fetch: Set.new([file_path]))
+
+      success = cli.execute_command(["check", file_path])
+
+      assert_includes string_io.string, "hi i am a custom offense formatter"
+      assert_includes string_io.string, "stale violations report"
+      assert_includes string_io.string, violation_message
+
+      refute success
+    end
   end
 end

test/unit/configuration_test.rb

@@ -13,7 +13,7 @@ class ConfigurationTest < Minitest::Test
 
     teardown do
       teardown_application_fixture
-      Object.send(:remove_const, :MyLocalExtension) if defined?(MyLocalExtension)
+      remove_extensions
     end
 
     test ".from_path raises ArgumentError if path does not exist" do