class Rack::Test::Session

def custom_request(verb, uri, params = {}, env = {}, &block)

custom_request "LINK", "/"

params and rack environment. Example:
Issue a request using the given HTTP verb for the given URI, with optional 
def custom_request(verb, uri, params = {}, env = {}, &block)
  uri = parse_uri(uri, env)
  env = env_for(uri, env.merge(method: verb.to_s.upcase, params: params))
  process_request(uri, env, &block)
end