Copy & adapt rake infrastructure from swiftgen projects

rakelib/Dangerfile

@@ -0,0 +1,97 @@
+# frozen_string_literal: true
+
+require_relative 'check_changelog'
+
+is_release = github.branch_for_head.start_with?('release/')
+is_hotfix = github.branch_for_head.start_with?('hotfix/')
+
+################################################
+# Welcome message
+markdown [
+  "Hey 👋 I'm Eve, the friendly bot watching over Stencil 🤖",
+  'Thanks a lot for your contribution!',
+  '', '---', ''
+]
+
+need_fixes = []
+
+################################################
+# Make it more obvious that a PR is a work in progress and shouldn't be merged yet
+warn('PR is classed as Work in Progress') if github.pr_title.include? '[WIP]'
+
+# Note when there is a big PR
+message('Big PR') if git.lines_of_code > 500 && !is_release
+
+################################################
+# Check for correct base branch
+if is_release
+  message('This is a Release PR')
+
+  require 'open3'
+
+  stdout, _, status = Open3.capture3('bundle', 'exec', 'rake', 'changelog:check')
+  markdown [
+    '',
+    '### ChangeLog check',
+    '',
+    stdout
+  ]
+  need_fixes << fail('Please fix the CHANGELOG errors') unless status.success?
+
+  stdout, _, status = Open3.capture3('bundle', 'exec', 'rake', 'release:check_versions')
+  markdown [
+    '',
+    '### Release version check',
+    '',
+    stdout
+  ]
+  need_fixes << fail('Please fix the versions inconsistencies') unless status.success?
+elsif is_hotfix
+  message('This is a Hotfix PR')
+end
+
+################################################
+# Check for a CHANGELOG entry
+declared_trivial = github.pr_title.include? '#trivial'
+has_changelog = git.modified_files.include?('CHANGELOG.md')
+changelog_msg = ''
+unless has_changelog || declared_trivial
+  repo_url = github.pr_json['head']['repo']['html_url']
+  pr_title = github.pr_title
+  pr_title += '.' unless pr_title.end_with?('.')
+  pr_number = github.pr_json['number']
+  pr_url = github.pr_json['html_url']
+  pr_author = github.pr_author
+  pr_author_url = "https://github.com/#{pr_author}"
+
+  need_fixes = fail("Please include a CHANGELOG entry to credit your work.  \nYou can find it at [CHANGELOG.md](#{repo_url}/blob/#{github.branch_for_head}/CHANGELOG.md).")
+
+  changelog_msg = <<-CHANGELOG_FORMAT.gsub(/^ *\|/, '')
+  |📝 We use the following format for CHANGELOG entries:
+  |```
+  |* #{pr_title}  
+  |  [##{pr_number}](#{pr_url})
+  |  [@#{pr_author}](#{pr_author_url})
+  |```
+  |:bulb: Don't forget to end the line describing your changes by a period and two spaces.
+  CHANGELOG_FORMAT
+  # changelog_msg is printed during the "Encouragement message" section, see below
+end
+
+changelog_warnings = check_changelog
+unless changelog_warnings.empty?
+  need_fixes << warn('Found some warnings in CHANGELOG.md')
+  changelog_warnings.each do |warning|
+    warn(warning[:message], file: 'CHANGELOG.md', line: warning[:line])
+  end
+end
+
+################################################
+# Encouragement message
+if need_fixes.empty?
+  markdown('Seems like everything is in order 👍 You did a good job here! 🤝')
+else
+  markdown('Once you fix those tiny nitpickings above, we should be good to go! 🙌')
+  markdown(changelog_msg) unless changelog_msg.empty?
+  markdown('ℹ️ _I will update this comment as you add new commits_')
+end