servlet = new HttpServlet() {};
request = new MockHttpServletRequest();
response = new MockHttpServletResponse();
chain = new MockFilterChain();
invocations = new ArrayList<OncePerRequestFilter>();
filter = new OncePerRequestFilter() {
@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
invocations.add(this);
filterChain.doFilter(request, response);
}