Unit testing a Router provider in Go - unit-testing

Question

I have a file in my project as :
package handlers
import (
"github.com/gorilla/mux"
)
type IHandlerProvider interface {
GetRouter() *mux.Router
}
type HandlerProvider struct{}
func (h HandlerProvider) GetRouter() *mux.Router {
r := mux.NewRouter()
r.HandleFunc("/health", Health).Methods("GET")
return r
}
What is the right way to unit test this? For instance:
package handlers
import (
"testing"
"github.com/stretchr/testify/assert"
)
func TestGetRouterOk(t *testing.T) {
var subject IHandlerProvider = HandlerProvider{}
router := subject.GetRouter()
assert.NotNil(t, router)
}
I can assert the object not being null, but how can I test the routes are correct?

Answer 1

If you want to test that the router is returning expected handler (vs test behaviour), you can do something like the following:
r := mux.NewRouter()
r.HandleFunc("/a", handlerA).Methods("GET")
r.HandleFunc("/b", handlerB).Methods("GET")
req, err := httptest.NewRequest("GET", "http://example.com/a", nil)
require.NoError(err, "create request")
m := &mux.RouteMatch{}
require.True(r.Match(req, m), "no match")
v1 := reflect.ValueOf(m.Handler)
v2 := reflect.ValueOf(handlerA)
require.Equal(v1.Pointer(), v2.Pointer(), "wrong handler")

Answer 2

You could use httptest package.
handlers.go:
package handlers
import (
"net/http"
"github.com/gorilla/mux"
)
type IHandlerProvider interface {
GetRouter() *mux.Router
}
type HandlerProvider struct {}
func Health(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("ok"))
}
func (h HandlerProvider) GetRouter() *mux.Router {
r := mux.NewRouter()
r.HandleFunc("/health", Health).Methods("GET")
return r
}
handlers_test.go:
package handlers
import (
"testing"
"bytes"
"io/ioutil"
"net/http/httptest"
)
func TestGetRouterOk(t *testing.T) {
assertResponseBody := func(t *testing.T, s *httptest.Server, expectedBody string) {
resp, err := s.Client().Get(s.URL+"/health")
if err != nil {
t.Fatalf("unexpected error getting from server: %v", err)
}
if resp.StatusCode != 200 {
t.Fatalf("expected a status code of 200, got %v", resp.StatusCode)
}
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
t.Fatalf("unexpected error reading body: %v", err)
}
if !bytes.Equal(body, []byte(expectedBody)) {
t.Fatalf("response should be ok, was: %q", string(body))
}
}
var subject IHandlerProvider = HandlerProvider{}
router := subject.GetRouter()
s := httptest.NewServer(router)
defer s.Close()
assertResponseBody(t, s, "ok")
}
unit test result:
=== RUN TestGetRouterOk
--- PASS: TestGetRouterOk (0.00s)
PASS
ok github.com/mrdulin/golang/src/stackoverflow/64584472 0.097s
coverage: