@Test
  public void grantAccessTokenMissingGrantType() throws Exception {
    oauth.clientId("resource-owner");

    DefaultHttpClient client = new DefaultHttpClient();
    try {
      HttpPost post = new HttpPost(oauth.getResourceOwnerPasswordCredentialGrantUrl());
      OAuthClient.AccessTokenResponse response =
          new OAuthClient.AccessTokenResponse(client.execute(post));

      assertEquals(400, response.getStatusCode());

      assertEquals("invalid_request", response.getError());
      assertEquals("Missing form parameter: grant_type", response.getErrorDescription());
    } finally {
      client.close();
    }
  }