Add unsupported_grant_type error

See spec: http://tools.ietf.org/html/rfc6749#section-5.2

Author: thomseddon

lib/error.js

@@ -43,6 +43,7 @@ function OAuth2Error (error, description, err) {
   switch (error) {
     case 'invalid_grant':
     case 'invalid_request':
+    case 'unsupported_grant_type':
       this.code = 400;
       break;
     case 'invalid_client':

lib/grant.js

@@ -73,9 +73,11 @@ function extractCredentials (done) {
 
   // Grant type
   this.grantType = this.req.body && this.req.body.grant_type;
-  if (!this.grantType || !this.grantType.match(this.config.regex.grantType)) {
+  if (!this.grantType) {
     return done(error('invalid_request',
       'Invalid or missing grant_type parameter'));
+  } else if (!this.grantType.match(this.config.regex.grantType)) {
+    return done(error('unsupported_grant_type', 'Unsupported grant type'));
   }
 
   // Extract credentials
@@ -165,8 +167,7 @@ function checkGrantType (done) {
     case 'client_credentials':
       return useClientCredentialsGrant.call(this, done);
     default:
-      done(error('invalid_request',
-        'Invalid grant_type parameter or parameter missing'));
+      done(error('unsupported_grant_type', 'Unsupported grant type'));
   }
 }
 

test/grant.extended.js

@@ -60,7 +60,7 @@ describe('Granting with extended grant type', function () {
         client_id: 'thom',
         client_secret: 'nightworld'
       })
-      .expect(400, /invalid grant_type/i, done);
+      .expect(400, /unsupported grant type/i, done);
   });
 
   it('should still detect unsupported grant_type', function (done) {

test/grant.js

@@ -83,7 +83,7 @@ describe('Grant', function() {
         .post('/oauth/token')
         .set('Content-Type', 'application/x-www-form-urlencoded')
         .send({ grant_type: 'password' })
-        .expect(400, /invalid or missing grant_type parameter/i, done);
+        .expect(400, /unsupported grant type/i, done);
     });
 
     it('should check client_id exists', function (done) {
@@ -179,7 +179,7 @@ describe('Grant', function() {
         .post('/oauth/token')
         .set('Content-Type', 'application/x-www-form-urlencoded')
         .send({ grant_type: 'password', client_id: 'thom', client_secret: 'nightworld' })
-        .expect(400, /invalid or missing grant_type/i, done);
+        .expect(400, /unsupported grant type/i, done);
     });
   });