chore(allsrv): replace http.DefaultServeMux with isolated `*http.Se…

…rveMux` dependency

This resolves the panic adding routes with the same pattern multiple
times. Now each `Server`, has its own `*http.ServeMux`. Now tests run independent
of one another and we avoid the pain of GLOBALS!

The tests should now pass :-)

allsrv/server.go

@@ -5,7 +5,7 @@ import (
 	"errors"
 	"log"
 	"net/http"
-	
+
 	"github.com/gofrs/uuid"
 )
 
@@ -18,7 +18,7 @@ import (
 		a) what happens if we forget that copy pasta?
 	3) auth is hardcoded to basic auth
 		a) what happens if we want to adapt some other means of auth?
-	4) router being used is the GLOBAL http.DefaultServeMux
+	✅4) router being used is the GLOBAL http.DefaultServeMux
 		a) should avoid globals
 		b) what happens if you have multiple servers in this go module who reference default serve mux?
 	5) no tests
@@ -45,10 +45,11 @@ import (
 */
 
 type Server struct {
-	db *InmemDB // 1)
-
+	db  *InmemDB       // 1)
+	mux *http.ServeMux // 4)
+
 	user, pass string // 3)
-	
+
 	idFn func() string // 11)
 }
 
@@ -62,6 +63,7 @@ func WithIDFn(fn func() string) func(*Server) {
 func NewServer(db *InmemDB, user, pass string, opts ...func(*Server)) *Server {
 	s := Server{
 		db:   db,
+		mux:  http.NewServeMux(), // 4)
 		user: user,
 		pass: pass,
 		idFn: func() string {
@@ -72,22 +74,22 @@ func NewServer(db *InmemDB, user, pass string, opts ...func(*Server)) *Server {
 	for _, o := range opts {
 		o(&s)
 	}
-	
+
 	s.routes()
 	return &s
 }
 
 func (s *Server) routes() {
 	// 4) 7) 9) 10)
-	http.Handle("POST /foo", http.HandlerFunc(s.createFoo))
-	http.Handle("GET /foo", http.HandlerFunc(s.readFoo))
-	http.Handle("PUT /foo", http.HandlerFunc(s.updateFoo))
-	http.Handle("DELETE /foo", http.HandlerFunc(s.delFoo))
+	s.mux.Handle("POST /foo", http.HandlerFunc(s.createFoo))
+	s.mux.Handle("GET /foo", http.HandlerFunc(s.readFoo))
+	s.mux.Handle("PUT /foo", http.HandlerFunc(s.updateFoo))
+	s.mux.Handle("DELETE /foo", http.HandlerFunc(s.delFoo))
 }
 
 func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// 4)
-	http.DefaultServeMux.ServeHTTP(w, r)
+	s.mux.ServeHTTP(w, r)
 }
 
 type Foo struct {
@@ -103,20 +105,20 @@ func (s *Server) createFoo(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusUnauthorized) // 9)
 		return
 	}
-	
+
 	var f Foo
 	if err := json.NewDecoder(r.Body).Decode(&f); err != nil {
 		w.WriteHeader(http.StatusForbidden) // 9)
 		return
 	}
-	
+
 	f.ID = s.idFn() // 11)
-	
+
 	if err := s.db.CreateFoo(f); err != nil {
 		w.WriteHeader(http.StatusInternalServerError) // 9)
 		return
 	}
-	
+
 	w.WriteHeader(http.StatusCreated)
 	if err := json.NewEncoder(w).Encode(f); err != nil {
 		log.Printf("unexpected error writing json value to response body: " + err.Error()) // 8) 10)
@@ -129,13 +131,13 @@ func (s *Server) readFoo(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusUnauthorized) // 9)
 		return
 	}
-	
+
 	f, err := s.db.readFoo(r.URL.Query().Get("id"))
 	if err != nil {
 		w.WriteHeader(http.StatusNotFound) // 9)
 		return
 	}
-	
+
 	if err := json.NewEncoder(w).Encode(f); err != nil {
 		log.Printf("unexpected error writing json value to response body: " + err.Error()) // 8) 10)
 	}
@@ -147,13 +149,13 @@ func (s *Server) updateFoo(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusUnauthorized) // 9)
 		return
 	}
-	
+
 	var f Foo
 	if err := json.NewDecoder(r.Body).Decode(&f); err != nil {
 		w.WriteHeader(http.StatusForbidden) // 9)
 		return
 	}
-	
+
 	if err := s.db.updateFoo(f); err != nil {
 		w.WriteHeader(http.StatusInternalServerError) // 9)
 		return
@@ -166,7 +168,7 @@ func (s *Server) delFoo(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusUnauthorized) // 9)
 		return
 	}
-	
+
 	if err := s.db.delFoo(r.URL.Query().Get("id")); err != nil {
 		w.WriteHeader(http.StatusNotFound) // 9)
 		return
@@ -184,9 +186,9 @@ func (db *InmemDB) CreateFoo(f Foo) error {
 			return errors.New("foo " + f.Name + " exists") // 8)
 		}
 	}
-	
+
 	db.m = append(db.m, f)
-	
+
 	return nil
 }