[#4] Add an RSpec test suite for the checks

.github/workflows/ci.yml

@@ -14,25 +14,41 @@ jobs:
     name: Ruby lint (standardrb)
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: "3.4"
           bundler-cache: true
       - run: bundle exec standardrb
 
+  rspec:
+    name: RSpec
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: "3.4"
+          bundler-cache: true
+      - run: bundle exec rspec
+      - uses: actions/upload-artifact@v7
+        if: always()
+        with:
+          name: coverage-report
+          path: coverage/
+
   reuse:
     name: REUSE Compliance Check
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
-      - uses: fsfe/reuse-action@v1.1
+      - uses: actions/checkout@v7
+      - uses: fsfe/reuse-action@v6
 
   xrefcheck:
     name: xrefcheck
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
       - uses: serokell/xrefcheck-action@v1
 
   danger:
@@ -44,7 +60,7 @@ jobs:
       issues: read
       pull-requests: write
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
         with:
           fetch-depth: 0
       - uses: ruby/setup-ruby@v1

.gitignore

@@ -9,3 +9,6 @@
 # Gem build artifacts
 /pkg/
 /*.gem
+
+# Test coverage report
+/coverage/

.rspec

@@ -0,0 +1,7 @@
+# SPDX-FileCopyrightText: 2026 Serokell <https://serokell.io/>
+#
+# SPDX-License-Identifier: MPL-2.0
+
+--require spec_helper
+--format documentation
+--color

.xrefcheck.yaml

@@ -9,9 +9,3 @@ exclusions:
   # Notion requires authentication; xrefcheck cannot verify these links.
   ignoreExternalRefsTo:
     - "https://app.notion.com/.*"
-    # TODO: remove once this repo goes public. While it's private, GitHub
-    # returns 404 (not 403) for any of its own pages (issues, PRs, Actions
-    # runs, etc.) to an unauthenticated request, indistinguishable from a
-    # genuinely broken link. Once public, this exclusion would silently
-    # hide real broken links instead.
-    - "https://github\\.com/serokell/danger(/.*)?"

CHANGES.md

@@ -0,0 +1,21 @@
+<!--
+   - SPDX-FileCopyrightText: 2026 Serokell <https://serokell.io>
+   -
+   - SPDX-License-Identifier: CC0-1.0
+   -->
+
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
+
+## [Unreleased]
+
+### Fixed
+
+- `check_merge_request` no longer calls the GitHub-only `mr_title`/`mr_body`
+  methods against a GitHub PR, which raised instead of reading the PR's
+  title/body (#6).
+- Fixed a typo in `check_merge_request`'s `ticket_links.scan` error message
+  ("expecs" → "expects") (#6).

CONTRIBUTING.md

@@ -25,6 +25,24 @@ Our pull request template contains a [checklist](.github/pull_request_template.m
 of acceptance criteria for your pull request. Please read it before you start
 contributing and make sure your contributions adhere to this checklist.
 
+### Running tests and lints
+
+```sh
+bundle install
+bundle exec rspec         # run the test suite
+bundle exec standardrb    # lint
+bundle exec reuse lint    # REUSE/SPDX compliance
+xrefcheck                 # check for broken links between files
+```
+
+All four run in CI on every pull request. `xrefcheck` isn't a Ruby
+gem; see [serokell/xrefcheck](https://github.com/serokell/xrefcheck)
+for installation instructions.
+
+`bundle exec rspec` also produces a test coverage report via
+[SimpleCov](https://github.com/simplecov-ruby/simplecov), written to
+`coverage/index.html`, and fails the run if coverage drops below 90%.
+
 ## Legal
 
 We want to make sure that our projects come with correct licensing information

Dangerfile

@@ -8,7 +8,11 @@ check_commits_style
 check_premerge_commits
 check_merge_request
 check_merge_commits
-check_license_headers
+check_license_headers(
+  license_headers_default_config.with(ignore_paths: ["spec/fixtures/"])
+)
 check_trailing_whitespace(
-  trailing_whitespace_default_config.with(ignore_paths: ["LICENSE", "LICENSES/"])
+  trailing_whitespace_default_config.with(
+    ignore_paths: ["LICENSE", "LICENSES/", "spec/fixtures/"]
+  )
 )

Gemfile

@@ -10,3 +10,8 @@ group :development do
   gem "ruby-lsp"
   gem "standard"
 end
+
+group :test do
+  gem "rspec"
+  gem "simplecov", require: false
+end

REUSE.toml

@@ -11,3 +11,15 @@ path = ".github/**"
 precedence = "aggregate"
 SPDX-FileCopyrightText = "2026 Serokell <https://serokell.io>"
 SPDX-License-Identifier = "CC0-1.0"
+
+[[annotations]]
+path = "spec/fixtures/pull_request_event.json"
+precedence = "aggregate"
+SPDX-FileCopyrightText = "2026 Serokell <https://serokell.io>"
+SPDX-License-Identifier = "CC0-1.0"
+
+[[annotations]]
+path = "spec/fixtures/no_license_header.md"
+precedence = "aggregate"
+SPDX-FileCopyrightText = "2026 Serokell <https://serokell.io>"
+SPDX-License-Identifier = "MPL-2.0"

lib/serokell_danger/checks/merge-request.rb

@@ -54,7 +54,7 @@ def check_merge_request(config = merge_request_default_config)
       case where.to_sym
       when :title then title
       when :body then body
-      else raise ArgumentError, "`ticket_links.scan` expecs :title and/or :body, got #{where.inspect}."
+      else raise ArgumentError, "`ticket_links.scan` expects :title and/or :body, got #{where.inspect}."
       end
     end.join("\n")
 

lib/serokell_danger/helpers.rb

@@ -33,17 +33,17 @@ def gitlab?
     end
 
     def mr_title
-      plugin.mr_title.to_s
+      githost_switch(:pr_title, :mr_title).to_s
     end
     alias_method :pr_title, :mr_title
 
     def mr_body
-      plugin.mr_body.to_s
+      githost_switch(:pr_body, :mr_body).to_s
     end
     alias_method :pr_body, :mr_body
 
     def mr_json
-      plugin.mr_json
+      githost_switch(:pr_json, :mr_json)
     end
     alias_method :pr_json, :mr_json
 
@@ -106,6 +106,11 @@ def respond_to_missing?(name, include_private = false)
 
     private
 
+    def githost_switch(on_github, on_gitlab, *args, **kwargs, &block)
+      return plugin.public_send(on_github, *args, **kwargs, &block) if github? && plugin.respond_to?(on_github)
+      plugin.public_send(on_gitlab, *args, **kwargs, &block)
+    end
+
     def json_field(gitlab_key, github_key)
       json = mr_json
       key = gitlab? ? gitlab_key : github_key

spec/fixtures/NoFinalNewline.hs

@@ -0,0 +1,7 @@
+-- SPDX-FileCopyrightText: 2026 Serokell <https://serokell.io/>
+--
+-- SPDX-License-Identifier: MPL-2.0
+module NoFinalNewline (main) where
+
+main :: IO ()
+main = putStrLn "Hello, world!"

spec/fixtures/TrailingWhitespaceExtraFinalNewlines.hs

@@ -0,0 +1,8 @@
+-- SPDX-FileCopyrightText: 2026 Serokell <https://serokell.io/>
+--
+-- SPDX-License-Identifier: MPL-2.0
+module TrailingWhitespaceExtraFinalNewlines (main) where   
+
+main :: IO ()  
+main = putStrLn "Hello, world!"   
+

spec/fixtures/no_license_header.md

@@ -0,0 +1 @@
+This fixture has no license header at all and should be silently skipped.

spec/fixtures/outdated_license_year.md

@@ -0,0 +1,7 @@
+<!--
+   - SPDX-FileCopyrightText: 2023 Serokell <https://serokell.io>
+   -
+   - SPDX-License-Identifier: MPL-2.0
+   -->
+
+This fixture has an outdated license year and should be flagged by the test.

spec/fixtures/outdated_year_and_wrong_holder.md

@@ -0,0 +1,7 @@
+<!--
+   - SPDX-FileCopyrightText: 2023 example <https://example.com>
+   -
+   - SPDX-License-Identifier: MPL-2.0
+   -->
+
+This fixture has both an outdated license year and the wrong copyright holder.

spec/fixtures/pull_request_event.json

@@ -0,0 +1,6 @@
+{
+  "number": 42,
+  "repository": {
+    "clone_url": "https://github.com/serokell/danger.git"
+  }
+}

spec/fixtures/wrong_copyright_holder.md

@@ -0,0 +1,7 @@
+<!--
+   - SPDX-FileCopyrightText: 2026 example <https://example.com>
+   -
+   - SPDX-License-Identifier: MPL-2.0
+   -->
+
+This fixture has the wrong copyright holder.