Suggestion feature

.github/workflows/test_rdjson_formatter.yml

@@ -0,0 +1,17 @@
+name: Test rdjson_formatter
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-ruby@v1
+        with:
+          ruby-version: '3.0.2'
+      - run: gem install rubocop
+      - name: Test rdjson_formatter
+        run: ./test/rdjson_formatter/test.sh

.rubocop.yml

@@ -0,0 +1,4 @@
+AllCops:
+  Exclude:
+    - 'test/rdjson_formatter/**/*'
+    - 'vendor/**/*'

rdjson_formatter/rdjson_formatter.rb

@@ -0,0 +1,121 @@
+# frozen_string_literal: true
+
+# https://docs.rubocop.org/rubocop/formatters.html
+# rubocop:disable Metrics/AbcSize, Metrics/MethodLength
+class RdjsonFormatter < RuboCop::Formatter::BaseFormatter
+  def started(_target_files)
+    @rdjson = {
+      source: {
+        name: 'rubocop',
+        url: 'https://rubocop.org/'
+      },
+      diagnostics: []
+    }
+    super
+  end
+
+  def file_finished(file, offenses)
+    offenses.each do |offense|
+      @rdjson[:diagnostics] << build_diagnostic(file, offense)
+    end
+  end
+
+  def finished(_inspected_files)
+    puts @rdjson.to_json
+  end
+
+  private
+
+  # @param [String] file
+  # @param [RuboCop::Cop::Offense] offense
+  # @return [Hash]
+  def build_diagnostic(file, offense)
+    code, message = offense.message.split(':', 2).map(&:strip)
+
+    diagnostic = {
+      message: message,
+      location: {
+        path: convert_path(file),
+        range: {
+          start: {
+            line: offense.location.begin.line,
+            column: offense.location.begin.column + 1
+          },
+          end: {
+            line: offense.location.end.line,
+            column: offense.location.end.column + 1
+          }
+        }
+      },
+      severity: convert_severity(offense.severity),
+      code: {
+        value: code
+      },
+      original_output: offense.to_s
+    }
+
+    diagnostic[:suggestions] = build_suggestions(offense) if offense.corrector
+
+    diagnostic
+  end
+
+  # @param [RuboCop::Cop::Offense] offense
+  # @return [Array{Hash}]
+  def build_suggestions(offense)
+    range, text = offense.corrector.as_replacements[0]
+
+    [
+      {
+        range: {
+          start: {
+            line: range.begin.line,
+            column: range.begin.column + 1 # rubocop is 0-origin, reviewdog is 1-origin
+          },
+          end: {
+            line: range.end.line,
+            column: range.end.column + 1
+          }
+        },
+        text: text
+      }
+    ]
+  end
+
+  # https://github.com/reviewdog/reviewdog/blob/1d8f6d6897dcfa67c33a2ccdc2ea23a8cca96c8c/proto/rdf/reviewdog.proto
+  # https://docs.rubocop.org/rubocop/configuration.html#severity
+  #
+  # @param [Symbol] severity
+  # @return [String]
+  def convert_severity(severity)
+    case severity
+    when :info
+      'INFO'
+    when :warning
+      'WARNING'
+    when :error
+      'ERROR'
+    else
+      'UNKNOWN_SEVERITY'
+    end
+  end
+
+  # extract reasonable relative path from (ideally) the project root.
+  # if `path` is `"/path/to/project/lib/my_file.rb"`,
+  # it generates `"lib/my_file.rb"` as
+  #
+  # ref: rubocop approach
+  # https://github.com/rubocop/rubocop/blob/1e55b1aa5e4c5eaeccad5d61f08b7930ed6bc341/lib/rubocop/path_util.rb#L25
+  #
+  # @param [String] path
+  # @return [String]
+  def convert_path(path)
+    base_path = Dir.pwd
+
+    begin
+      Pathname.new(File.expand_path(path)).relative_path_from(base_path).to_s
+    rescue ArgumentError
+      path
+    end
+  end
+end
+# rubocop:enable Metrics/AbcSize, Metrics/MethodLength

script.sh

@@ -92,8 +92,8 @@ fi
 
 echo '::group:: Running rubocop with reviewdog 🐶 ...'
 # shellcheck disable=SC2086
-${BUNDLE_EXEC}rubocop ${INPUT_RUBOCOP_FLAGS} \
-  | reviewdog -f=rubocop \
+${BUNDLE_EXEC}rubocop ${INPUT_RUBOCOP_FLAGS} --require ${GITHUB_ACTION_PATH}/rdjson_formatter/rdjson_formatter.rb --format RdjsonFormatter \
+  | reviewdog -f=rdjson \
       -name="${INPUT_TOOL_NAME}" \
       -reporter="${INPUT_REPORTER}" \
       -filter-mode="${INPUT_FILTER_MODE}" \

test/rdjson_formatter/test.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+# Expected to run from the root repository.
+set -eux
+CWD=$(pwd)
+rubocop ./test/rdjson_formatter/testdata/*.rb --require ./rdjson_formatter/rdjson_formatter.rb --format RdjsonFormatter --cache false \
+  | jq . \
+  | sed -e "s!${CWD}/!!g" \
+  > ./test/rdjson_formatter/testdata/result.out
+diff -u ./test/rdjson_formatter/testdata/result.*

test/rdjson_formatter/testdata/.gitignore

@@ -0,0 +1 @@
+*.out

test/rdjson_formatter/testdata/correctable_offenses.rb

@@ -0,0 +1,4 @@
+def add(xyz,abc)
+  a    = xyz+   abc;
+  return  a
+end

test/rdjson_formatter/testdata/not_correctable_offenses.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+class MyClass < Object
+  def no_calc(a, b)
+    c = a + b
+    a
+  end
+end