Add onebox for GitHub pull requests

spec/components/oneboxer/github_pullrequest_onebox_spec.rb

@@ -0,0 +1,17 @@
+require 'spec_helper'
+require 'oneboxer'
+require 'oneboxer/github_pullrequest_onebox'
+
+describe Oneboxer::GithubPullrequestOnebox do
+  describe '#translate_url' do
+    it 'returns the api url for the given pull request' do
+      onebox = described_class.new(
+        'https://github.com/discourse/discourse/pull/988'
+      )
+      expect(onebox.translate_url).to eq(
+        'https://api.github.com/repos/discourse/discourse/pulls/988'
+      )
+    end
+  end
+end
+