(maint) Add markdown lint checking to markdown tests

Gemfile

@@ -20,6 +20,7 @@ group :test do
   gem 'simplecov-console'
   gem 'rspec', '~> 3.1'
   gem 'json_spec', '~> 1.1', '>= 1.1.5'
+  gem 'mdl', '~> 0.8.0' if Gem::Version.new(RUBY_VERSION.dup) >= Gem::Version.new('2.4.0')
 end
 
 group :acceptance do

spec/spec_helper.rb

@@ -47,3 +47,45 @@
     YARD::Registry.clear
   end
 end
+
+def mdl_available
+  @mdl_available ||= !Gem::Specification.select { |item| item.name.casecmp('mdl').zero? }.empty?
+end
+
+def lint_markdown(content)
+  return [] unless mdl_available
+  require 'mdl'
+
+  ruleset = MarkdownLint::RuleSet.new
+  ruleset.load_default
+
+  # All rules
+  style = MarkdownLint::Style.load('all', ruleset.rules)
+
+  # Create a document
+  doc = MarkdownLint::Doc.new(content, false)
+
+  # Run the rules
+  violations = []
+  ruleset.rules.each do |id, rule|
+    error_lines = rule.check.call(doc)
+    next if error_lines.nil? or error_lines.empty?
+    # record the error
+    error_lines.each do |line|
+      line += doc.offset # Correct line numbers for any yaml front matter
+      violations << "#{filename}:#{line}: #{id} #{rule.description}"
+    end
+  end
+  violations
+end
+
+RSpec::Matchers.define :have_no_markdown_lint_errors do
+  match do |actual|
+    @violations = lint_markdown(actual)
+    @violations.empty?
+  end
+
+  failure_message do |actual|
+    "expected that #{actual.length > 80 ? actual.slice(0,80).inspect + '...' : actual.inspect} would have no markdown lint errors but got #{@violations.join("\n")}"
+  end
+end

spec/unit/puppet-strings/markdown_spec.rb

@@ -325,6 +325,17 @@ def parse_data_type_content
   let(:baseline_path) { File.join(File.dirname(__FILE__), "../../fixtures/unit/markdown/#{filename}") }
   let(:baseline) { File.read(baseline_path) }
 
+  RSpec.shared_examples 'markdown lint checker' do |parameter|
+    it 'should not generate markdown lint errors from the rendered markdown', if: mdl_available do
+      pending('Failures are expected')
+      Tempfile.open('md') do |file|
+        PuppetStrings::Markdown.render(file.path)
+
+        expect(File.read(file.path)).to have_no_markdown_lint_errors
+      end
+    end
+  end
+
   describe 'rendering markdown to a file' do
     before(:each) do
       parse_shared_content
@@ -339,6 +350,8 @@ def parse_data_type_content
           expect(File.read(file.path)).to eq(baseline)
         end
       end
+
+      include_examples 'markdown lint checker'
     end
 
     describe 'with Puppet Plans', :if => TEST_PUPPET_PLANS do
@@ -354,6 +367,8 @@ def parse_data_type_content
           expect(File.read(file.path)).to eq(baseline)
         end
       end
+
+      include_examples 'markdown lint checker'
     end
 
     describe 'with Puppet Data Types', :if => TEST_PUPPET_DATATYPES do
@@ -369,6 +384,8 @@ def parse_data_type_content
           expect(File.read(file.path)).to eq(baseline)
         end
       end
+
+      include_examples 'markdown lint checker'
     end
   end
 end