Add GitHub Actions reporter to support custom offense formatting

lib/erb_lint/reporters/github_actions_reporter.rb

@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+module ERBLint
+  module Reporters
+    class GithubActionsReporter < ERBLint::Reporter
+      ESCAPE_MAP = { "%" => "%25", "\n" => "%0A", "\r" => "%0D" }.freeze
+
+      def preview; end
+
+      def show
+        puts formatted_data
+      end
+
+      private
+
+      def formatted_data
+        formatted_files.join("\n")
+      end
+
+      def formatted_files
+        processed_files.flat_map do |filename, offenses|
+          offenses.map do |offense|
+            format_offense(filename, offense)
+          end
+        end
+      end
+
+      def format_offense(filename, offense)
+        message = github_escape("#{offense.simple_name}: #{offense.message}")
+        severity = github_severity(offense)
+
+        "::#{severity} file=#{filename},line=#{offense.line_number},col=#{offense.column}::#{message}"
+      end
+
+      def github_escape(string)
+        string.gsub(Regexp.union(ESCAPE_MAP.keys), ESCAPE_MAP)
+      end
+
+      def github_severity(offense)
+        [nil, :error, :fatal].include?(offense.severity) ? "warning" : "error"
+      end
+    end
+  end
+end

spec/erb_lint/cli_spec.rb

@@ -92,7 +92,7 @@ def run(processed_source)
       it "shows format instructions" do
         expect { subject }.to(
           output(Regexp.new("Report offenses in the given format: " \
-            "\\(compact, gitlab, json, junit, multiline\\) " \
+            "\\(compact, github_actions, gitlab, json, junit, multiline\\) " \
             "\\(default: multiline\\)")).to_stdout,
         )
       end
@@ -527,6 +527,7 @@ def run(processed_source)
               expect { subject }.to(output(Regexp.new(Regexp.escape(<<~EOF.strip))).to_stderr)
                 nonexistentformat: is not a valid format. Available formats:
                   - compact
+                  - github_actions
                   - gitlab
                   - json
                   - junit

spec/erb_lint/reporters/github_actions_reporter_spec.rb

@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+describe ERBLint::Reporters::GithubActionsReporter do
+  describe ".show" do
+    subject { described_class.new(stats, false).show }
+
+    let(:stats) do
+      ERBLint::Stats.new(
+        found: 2,
+        processed_files: {
+          "app/views/subscriptions/_loader.html.erb" => offenses,
+        },
+        corrected: 1,
+      )
+    end
+
+    let(:offenses) do
+      [
+        instance_double(
+          ERBLint::Offense,
+          message: "Extra space detected where there should be no space.",
+          line_number: 1,
+          column: 7,
+          simple_name: "SpaceInHtmlTag",
+          severity: :warning,
+          last_line: 1,
+          last_column: 9,
+          length: 2,
+        ),
+        instance_double(
+          ERBLint::Offense,
+          message: "Remove newline before `%>` to match start of tag.",
+          line_number: 52,
+          column: 10,
+          simple_name: "ClosingErbTagIndent",
+          severity: :error,
+          last_line: 54,
+          last_column: 10,
+          length: 10,
+        ),
+      ]
+    end
+
+    let(:expected_lines) do
+      [
+        "::error file=app/views/subscriptions/_loader.html.erb,line=1,col=7" \
+          "::SpaceInHtmlTag: Extra space detected where there should be no space.",
+        "::warning file=app/views/subscriptions/_loader.html.erb,line=52,col=10" \
+          "::ClosingErbTagIndent: Remove newline before `%25>` to match start of tag.",
+      ].join("\n")
+    end
+
+    it "displays formatted offenses output" do
+      expect { subject }.to(output(expected_lines + "\n").to_stdout)
+    end
+  end
+end