Add grant_types_supported to discovery response

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## Unreleased
 
 - [#114] Fix user_info endpoint when used in api mode
+- [#112] Add grant_types_supported to discovery response
 
 ## v1.7.2 (2020-05-20)
 

app/controllers/doorkeeper/openid_connect/discovery_controller.rb

@@ -39,6 +39,7 @@ def provider_response
           # TODO: support id_token response type
           response_types_supported: doorkeeper.authorization_response_types,
           response_modes_supported: ['query', 'fragment'],
+          grant_types_supported: grant_types_supported(doorkeeper),
 
           token_endpoint_auth_methods_supported: [
             'client_secret_basic',
@@ -73,6 +74,12 @@ def provider_response
         }.compact
       end
 
+      def grant_types_supported(doorkeeper)
+        grant_types_supported = doorkeeper.grant_flows
+        grant_types_supported << 'refresh_token' if doorkeeper.refresh_token_enabled?
+        grant_types_supported
+      end
+
       def webfinger_response
         {
           subject: params.require(:resource),

spec/controllers/discovery_controller_spec.rb

@@ -21,6 +21,7 @@
 
         'response_types_supported' => ['code'],
         'response_modes_supported' => ['query', 'fragment'],
+        'grant_types_supported' => %w[authorization_code client_credentials],
 
         'token_endpoint_auth_methods_supported' => [
           'client_secret_basic',
@@ -57,6 +58,17 @@
       }.sort)
     end
 
+    context 'when refresh_token grant type is enabled' do
+      before { Doorkeeper.configure { use_refresh_token } }
+
+      it 'add refresh_token to grant_types_supported' do
+        get :provider
+        data = JSON.parse(response.body)
+
+        expect(data['grant_types_supported']).to eq %w[authorization_code client_credentials refresh_token]
+      end
+    end
+
     it 'uses the protocol option for generating URLs' do
       Doorkeeper::OpenidConnect.configure do
         protocol { :testing }