    @Test
    public void when_OAuthException_return_response_with_exception_status() throws Exception {

        // GIVEN
        HttpRequest req = mock(HttpRequest.class);
        AuthorizationServer auth = mock(AuthorizationServer.class);
        OAuthException ex = new OAuthException(Response.NAME_OR_SCOPE_OR_URI_IS_NULL,
                HttpResponseStatus.BAD_REQUEST);
        willThrow(ex).given(auth).issueClientCredentials(req);
        handler.auth = auth;

        // WHEN
        HttpResponse response = handler.handleRegister(req);

        // THEN
        assertEquals(response.getStatus(), ex.getHttpStatus());
    }