Use an automated PR linter, danger.systems.

Author: dblock

.travis.yml

@@ -4,6 +4,9 @@ sudo: false
 
 matrix:
   include:
+    - rvm: 2.3.1
+      script:
+        - bundle exec danger
     - rvm: 2.3.1
       env: MODEL_PARSER=grape-swagger-entity
     - rvm: 2.3.1

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 #### Features
 
+* [#](https://github.com/ruby-grape/grape/pull/): Use an automated PR linter, [danger.systems](http://danger.systems) - [@dblock](https://github.com/dblock).
+
 * Your contribution here.
 
 #### Fixes

Dangerfile

@@ -0,0 +1,80 @@
+# --------------------------------------------------------------------------------------------------------------------
+# Has any changes happened inside the actual library code?
+# --------------------------------------------------------------------------------------------------------------------
+has_app_changes = !git.modified_files.grep(/lib/).empty?
+has_spec_changes = !git.modified_files.grep(/spec/).empty?
+
+# --------------------------------------------------------------------------------------------------------------------
+# You've made changes to lib, but didn't write any tests?
+# --------------------------------------------------------------------------------------------------------------------
+if has_app_changes && !has_spec_changes
+  raise("There're library changes, but not tests. That's OK as long as you're refactoring existing code.", sticky: false)
+end
+
+# --------------------------------------------------------------------------------------------------------------------
+# You've made changes to specs, but no library code has changed?
+# --------------------------------------------------------------------------------------------------------------------
+if !has_app_changes && has_spec_changes
+  message('We really appreciate pull requests that demonstrate issues, even without a fix. That said, the next step is to try and fix the failing tests!', sticky: false)
+end
+
+# --------------------------------------------------------------------------------------------------------------------
+# Have you updated CHANGELOG.md?
+# --------------------------------------------------------------------------------------------------------------------
+if !git.modified_files.include?('CHANGELOG.md') && has_app_changes
+  pr_number = github.pr_json['number']
+  markdown <<-MARKDOWN
+Here's an example of a CHANGELOG.md entry:
+
+```markdown
+* [##{pr_number}](https://github.com/ruby-grape/grape/pull/#{pr_number}): #{github.pr_title} - [@#{github.pr_author}](https://github.com/#{github.pr_author}).
+```
+MARKDOWN
+  raise('Please update CHANGELOG.md.', sticky: false)
+end
+
+# --------------------------------------------------------------------------------------------------------------------
+# Is the CHANGELOG.md format correct?
+# --------------------------------------------------------------------------------------------------------------------
+
+your_contribution_here = false
+releases = 0
+errors = 0
+File.open('CHANGELOG.md').each_line do |line|
+  # only look at the top releases, we entered a lot of changes without a PR before
+  if line == "==================\n"
+    releases += 1
+    break if releases == 5
+  end
+  # ignore lines that aren't changes
+  next unless line[0] == '*'
+  # notice your contribution here
+  if line == "* Your contribution here.\n"
+    your_contribution_here = true
+    next
+  end
+  # match the PR format
+  next if line =~ %r{^\*\s\[\#\d+\]\(https:\/\/github\.com\/.*\d+\)\: [\`[:upper:]].* \- \[\@[\w\d\-\_]+\]\(https:\/\/github\.com\/.*[\w\d\-\_]+\)\.$}
+  errors += 1
+  markdown <<-MARKDOWN
+```markdown
+#{line}```
+  MARKDOWN
+end
+
+raise("One of the lines below found in CHANGELOG.md doesn't match the expected format. Please make it look like the other lines, pay attention to periods and spaces.", sticky: false) if errors > 0
+raise('Please put back the `* Your contribution here.` line into CHANGELOG.md.', sticky: false) unless your_contribution_here
+
+# --------------------------------------------------------------------------------------------------------------------
+# Don't let testing shortcuts get into master by accident,
+# ensuring that we don't get green builds based on a subset of tests.
+# --------------------------------------------------------------------------------------------------------------------
+
+(git.modified_files + git.added_files - %w(Dangerfile)).each do |file|
+  next unless File.file?(file)
+  contents = File.read(file)
+  if file.start_with?('spec')
+    raise("`xit` or `fit` left in tests (#{file})") if contents =~ /^\w*[xf]it/
+    raise("`fdescribe` left in tests (#{file})") if contents =~ /^\w*fdescribe/
+  end
+end

Gemfile

@@ -15,3 +15,5 @@ if RUBY_VERSION < '2.2.2'
   gem 'rack', '<2.0.0'
   gem 'activesupport', '<5.0.0'
 end
+
+gem 'danger', '~> 2.0'