Spring Security Add SecurityMockMvcResultMatchers.withAuthorities(String...)

There should be a SecurityMockMvcResultMatchers.withAuthorities(String...) method which does not care about the GrantedAuthority implementation.

If the currently authenticated user has a custom GrantedAuthority implementation with the GrantedAuthority#getAuthority() of CUSTOM, then the following should work:

this.mockMvc.perform(formLogin().user("custom"))
            .andExpect(authenticated().withAuthorities("CUSTOM"));