You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: register_secret_test.go
    path of file: ./repos/dendrite/clientapi/routing
    
    the code of the file until where you have to start completion: package routing

import (
	"bytes"
	"io"
	"testing"

	"github.com/patrickmn/go-cache"
)

func TestSharedSecretRegister(t *testing.T) {
	// these values have come from a local synapse instance to ensure compatibility
	jsonStr := []byte(`{"admin":false,"mac":"f1ba8d37123866fd659b40de4bad9b0f8965c565","nonce":"759f047f312b99ff428b21d581256f8592b8976e58bc1b543972dc6147e529a79657605b52d7becd160ff5137f3de11975684319187e06901955f79e5a6c5a79","password":"wonderland","username":"alice","displayname":"rabbit"}`)
	sharedSecret := "dendritetest"

    
func TestSharedSecretRegister(t *testing.T) {
	// these values have come from a local synapse instance to ensure compatibility
	jsonStr := []byte(`{"admin":false,"mac":"f1ba8d37123866fd659b40de4bad9b0f8965c565","nonce":"759f047f312b99ff428b21d581256f8592b8976e58bc1b543972dc6147e529a79657605b52d7becd160ff5137f3de11975684319187e06901955f79e5a6c5a79","password":"wonderland","username":"alice","displayname":"rabbit"}`)
	sharedSecret := "dendritetest"

	req, err := NewSharedSecretRegistrationRequest(io.NopCloser(bytes.NewBuffer(jsonStr)))
	if err != nil {
		t.Fatalf("failed to read request: %s", err)
	}

	r := NewSharedSecretRegistration(sharedSecret)

	// force the nonce to be known
	r.nonces.Set(req.Nonce, true, cache.DefaultExpiration)

	valid, err := r.IsValidMacLogin(req.Nonce, req.User, req.Password, req.Admin, req.MacBytes)
	if err != nil {
		t.Fatalf("failed to check for valid mac: %s", err)
	}
	if !valid {
		t.Errorf("mac login failed, wanted success")
	}

	// modify the mac so it fails
	req.MacBytes[0] = 0xff
	valid, err = r.IsValidMacLogin(req.Nonce, req.User, req.Password, req.Admin, req.MacBytes)
	if err != nil {
		t.Fatalf("failed to check for valid mac: %s", err)
	}
	if valid {
		t.Errorf("mac login succeeded, wanted failure")
	}
}