feat: Renew access token with refresh access token

lib/octokit/client/users.rb

@@ -57,6 +57,33 @@ def exchange_code_for_token(code, app_id = client_id, app_secret = client_secret
         post "#{web_endpoint}login/oauth/access_token", options
       end
 
+      # Refresh a user's access token with a refresh token.
+      #
+      # Applications can refresh an access token without requiring a user to re-authorize using refresh access token.
+      #
+      # @param code [String] 40 character GitHub OAuth refresh access token
+      #
+      # @return [Sawyer::Resource]
+      # @see https://docs.github.com/en/apps/creating-github-apps/authenticating-with-a-github-app/refreshing-user-access-tokens#refreshing-a-user-access-token-with-a-refresh-token
+      #
+      # @example
+      #  client = Octokit::Client.new(:client_id => 'abcdefg12345', :client_secret => 'secret')
+      #  client.refresh_access_token('40-character-refresh-token')
+      def refresh_access_token(code, app_id = client_id, app_secret = client_secret, options = {})
+        options = options.merge({
+                                  refresh_token: code,
+                                  client_id: app_id,
+                                  client_secret: app_secret,
+                                  grant_type: 'refresh_token',
+                                  headers: {
+                                    content_type: 'application/json',
+                                    accept: 'application/json'
+                                  }
+                                })
+
+        post "#{web_endpoint}login/oauth/access_token", options
+      end
+
       # Validate user username and password
       #
       # @param options [Hash] User credentials

spec/fixtures/renew_access_token.json

@@ -0,0 +1,8 @@
+{
+  "scope": "",
+  "expires_in": 28800,
+  "token_type": "bearer",
+  "access_token": "new_access_token",
+  "refresh_token": "new_refresh_token",
+  "refresh_token_expires_in": 15811200
+}

spec/octokit/client/users_spec.rb

@@ -267,6 +267,49 @@
     end # with credentials passed as parameters
   end # .exchange_code_for_token
 
+  describe '.refresh_access_token' do
+    context 'with application authenticated client' do
+      it 'returns the access_token' do
+        request_body = {
+          refresh_token: 'code',
+          client_id: '123',
+          client_secret: '345',
+          grant_type: 'refresh_token'
+        }
+
+        client = Octokit::Client.new(
+          client_id: request_body[:client_id],
+          client_secret: request_body[:client_secret]
+        )
+
+        request = stub_post('https://github.com/login/oauth/access_token')
+                  .with(
+                    basic_auth: [request_body[:client_id], request_body[:client_secret]],
+                    body: request_body.to_json
+                  ).to_return(json_response('renew_access_token.json'))
+
+        response = client.refresh_access_token('code')
+
+        expect(response.access_token).to eq 'new_access_token'
+        expect(response.refresh_token).to eq 'new_refresh_token'
+        assert_requested request
+      end
+    end # with application authenticated client
+
+    context 'with credentials passed as parameters by unauthed client' do
+      it 'returns the access_token' do
+        client = Octokit::Client.new
+        post = stub_request(:post, 'https://github.com/login/oauth/access_token')
+               .with(body: { refresh_token: 'code', client_id: 'id', client_secret: 'secret', grant_type: 'refresh_token' }.to_json)
+               .to_return(json_response('renew_access_token.json'))
+        response = client.refresh_access_token('code', 'id', 'secret')
+        expect(response.access_token).to eq 'new_access_token'
+        expect(response.refresh_token).to eq 'new_refresh_token'
+        assert_requested post
+      end # with credentials passed as parameters
+    end # .refresh_access_token
+  end
+
   describe '.migrations', :vcr do
     it 'starts a migration for a user' do
       result = @client.start_user_migration(['snakeoil-ceo/the-insecure'], lock_repositories: true)