Rakefile in govuk_markdown-2.0.1 vs Rakefile in govuk_markdown-2.0.2

@@ -1,16 +1,29 @@
+require "mkmf"
 require "bundler/gem_tasks"
+require "rspec/core/rake_task"
+
+RSpec::Core::RakeTask.new(:spec)
+
 task default: :spec
 
 desc "Regenerate the example HTML in example/example.html"
 task :generate_example do
   require_relative "lib/govuk_markdown"
 
   markdown = File.read("example/example.md")
   html = GovukMarkdown.render(markdown)
 
   File.write("example/example.html", ERB.new(File.read("example/example_layout.html.erb")).result(binding))
-  sh "open example/example.html"
+
+  case
+  when find_executable("xdg-open")     # linux
+    sh("xdg-open example/example.html")
+  when find_executable("open")         # mac
+    sh("open example/example.html")
+  else
+    puts "View the example in example/example.html"
+  end
 end
 
 desc "Print the current version of the gem"
 task :gem_version do
   require_relative "lib/govuk_markdown/version"