Add GitLab reporter (#343)

README.md

@@ -643,6 +643,42 @@ erblint --format junit
 </testsuite>
 ```
 
+### GitLab
+
+Used by [GitLab Code
+Quality](https://docs.gitlab.com/ee/ci/testing/code_quality.html#implement-a-custom-tool).
+
+```json
+[
+   {
+      "description":"Extra space detected where there should be no space.",
+      "check_name":"SpaceInHtmlTag",
+      "fingerprint":"5a259c7cafa2c9ca229dfd7d21536698",
+      "severity":"info",
+      "location":{
+         "path":"app/views/subscriptions/_loader.html.erb",
+         "lines":{
+            "begin":1,
+            "end":1
+         }
+      }
+   },
+   {
+      "description":"Remove newline before `%\u003e` to match start of tag.",
+      "check_name":"ClosingErbTagIndent",
+      "fingerprint":"60b4ed2120c7abeebebb43fba4a19559",
+      "severity":"warning",
+      "location":{
+         "path":"app/views/subscriptions/_loader.html.erb",
+         "lines":{
+            "begin":52,
+            "end":54
+         }
+      }
+   }
+]
+```
+
 ## Caching
 
 The cache is currently opt-in - to turn it on, use the `--cache` option:

lib/erb_lint/reporters/gitlab_reporter.rb

@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+
+require "json"
+
+module ERBLint
+  module Reporters
+    class GitlabReporter < Reporter
+      def preview; end
+
+      def show
+        puts formatted_data
+      end
+
+      private
+
+      def formatted_data
+        formatted_files.to_json
+      end
+
+      def formatted_files
+        processed_files.flat_map do |filename, offenses|
+          formatted_offenses(filename, offenses)
+        end
+      end
+
+      def formatted_offenses(filename, offenses)
+        offenses.map do |offense|
+          format_offense(filename, offense)
+        end
+      end
+
+      def format_offense(filename, offense)
+        {
+          description: offense.message,
+          check_name: offense.simple_name,
+          fingerprint: generate_fingerprint(filename, offense),
+          severity: offense.severity,
+          location: {
+            path: filename,
+            lines: {
+              begin: offense.line_number,
+              end: offense.last_line,
+            },
+          },
+        }
+      end
+
+      def generate_fingerprint(filename, offense)
+        Digest::MD5.hexdigest(
+          "#{offense.simple_name}@#{filename}:#{offense.line_number}:#{offense.last_line}"
+        )
+      end
+    end
+  end
+end

spec/erb_lint/cli_spec.rb

@@ -91,7 +91,7 @@ def run(processed_source)
       it "shows format instructions" do
         expect { subject }.to(
           output(Regexp.new("Report offenses in the given format: " \
-            "\\(compact, json, junit, multiline\\) " \
+            "\\(compact, gitlab, json, junit, multiline\\) " \
             "\\(default: multiline\\)")).to_stdout
         )
       end
@@ -504,6 +504,7 @@ 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
+                  - gitlab
                   - json
                   - junit
                   - multiline

spec/erb_lint/reporters/gitlab_reporter_spec.rb

@@ -0,0 +1,81 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+describe ERBLint::Reporters::GitlabReporter 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: "info",
+          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: "warning",
+          last_line: 54,
+          last_column: 10,
+          length: 10,
+        ),
+      ]
+    end
+
+    let(:expected_hash) do
+      [
+        {
+          description: "Extra space detected where there should be no space.",
+          check_name: "SpaceInHtmlTag",
+          fingerprint: "5a259c7cafa2c9ca229dfd7d21536698",
+          severity: "info",
+          location: {
+            path: "app/views/subscriptions/_loader.html.erb",
+            lines: {
+              begin: 1,
+              end: 1,
+            },
+          },
+        },
+        {
+          description: "Remove newline before `%>` to match start of tag.",
+          check_name: "ClosingErbTagIndent",
+          fingerprint: "60b4ed2120c7abeebebb43fba4a19559",
+          severity: "warning",
+          location: {
+            path: "app/views/subscriptions/_loader.html.erb",
+            lines: {
+              begin: 52,
+              end: 54,
+            },
+          },
+        },
+      ]
+    end
+
+    it "displays formatted offenses output" do
+      expect { subject }.to(output(expected_hash.to_json + "\n").to_stdout)
+    end
+  end
+end