Add comprehensive test coverage for server/ package

Cover edge cases: statusWriter multi-call/default/unwrap, UUID v4 format
and uniqueness, non-string panics, recovery body and log attributes,
4xx log level, default status in logging, request ID propagation,
server defaults/options/listen-error/multiple-hooks/logger, router
groups with empty prefix/inherited middleware/ordering/path params/
isolation, mount trailing slash, health content-type and POST rejection.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/route_test.go

@@ -140,4 +140,197 @@ func TestRouterMount(t *testing.T) {
 			t.Fatalf("got body %q, want %q", body, "info")
 		}
 	})
+
+	t.Run("mount with trailing slash", func(t *testing.T) {
+		sub := http.NewServeMux()
+		sub.HandleFunc("GET /data", func(w http.ResponseWriter, _ *http.Request) {
+			_, _ = w.Write([]byte("data"))
+		})
+
+		r := server.NewRouter()
+		r.Mount("/sub/", sub)
+
+		w := httptest.NewRecorder()
+		req := httptest.NewRequest(http.MethodGet, "/sub/data", nil)
+		r.ServeHTTP(w, req)
+
+		body, _ := io.ReadAll(w.Body)
+		if string(body) != "data" {
+			t.Fatalf("got body %q, want %q", body, "data")
+		}
+	})
+}
+
+func TestRouter_PatternWithoutMethod(t *testing.T) {
+	r := server.NewRouter()
+	r.HandleFunc("/static/", func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write([]byte("static"))
+	})
+
+	for _, method := range []string{http.MethodGet, http.MethodPost} {
+		w := httptest.NewRecorder()
+		req := httptest.NewRequest(method, "/static/file.css", nil)
+		r.ServeHTTP(w, req)
+
+		if w.Code != http.StatusOK {
+			t.Fatalf("%s /static/file.css: got status %d, want %d", method, w.Code, http.StatusOK)
+		}
+	}
+}
+
+func TestRouter_GroupEmptyPrefix(t *testing.T) {
+	r := server.NewRouter()
+	g := r.Group("")
+	g.HandleFunc("GET /hello", func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write([]byte("hello"))
+	})
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/hello", nil)
+	r.ServeHTTP(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("got status %d, want %d", w.Code, http.StatusOK)
+	}
+	if body := w.Body.String(); body != "hello" {
+		t.Fatalf("got body %q, want %q", body, "hello")
+	}
+}
+
+func TestRouter_GroupInheritsMiddleware(t *testing.T) {
+	var order []string
+
+	parentMW := func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			order = append(order, "parent")
+			next.ServeHTTP(w, r)
+		})
+	}
+	childMW := func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			order = append(order, "child")
+			next.ServeHTTP(w, r)
+		})
+	}
+
+	r := server.NewRouter()
+	parent := r.Group("/api", parentMW)
+	child := parent.Group("/v1", childMW)
+	child.HandleFunc("GET /items", func(w http.ResponseWriter, _ *http.Request) {
+		order = append(order, "handler")
+		w.WriteHeader(http.StatusOK)
+	})
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/items", nil)
+	r.ServeHTTP(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("got status %d, want %d", w.Code, http.StatusOK)
+	}
+
+	expected := []string{"parent", "child", "handler"}
+	if len(order) != len(expected) {
+		t.Fatalf("got %v, want %v", order, expected)
+	}
+	for i, v := range expected {
+		if order[i] != v {
+			t.Fatalf("order[%d] = %q, want %q", i, order[i], v)
+		}
+	}
+}
+
+func TestRouter_GroupMiddlewareOrder(t *testing.T) {
+	var order []string
+
+	mwA := func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			order = append(order, "A")
+			next.ServeHTTP(w, r)
+		})
+	}
+	mwB := func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			order = append(order, "B")
+			next.ServeHTTP(w, r)
+		})
+	}
+
+	r := server.NewRouter()
+	g := r.Group("/api", mwA)
+	sub := g.Group("/v1", mwB)
+	sub.HandleFunc("GET /test", func(w http.ResponseWriter, _ *http.Request) {
+		order = append(order, "handler")
+		w.WriteHeader(http.StatusOK)
+	})
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/test", nil)
+	r.ServeHTTP(w, req)
+
+	// Parent MW (A) should run before child MW (B), then handler.
+	expected := []string{"A", "B", "handler"}
+	if len(order) != len(expected) {
+		t.Fatalf("got %v, want %v", order, expected)
+	}
+	for i, v := range expected {
+		if order[i] != v {
+			t.Fatalf("order[%d] = %q, want %q", i, order[i], v)
+		}
+	}
+}
+
+func TestRouter_PathParamWithGroup(t *testing.T) {
+	r := server.NewRouter()
+	api := r.Group("/api")
+	api.HandleFunc("GET /users/{id}", func(w http.ResponseWriter, req *http.Request) {
+		_, _ = w.Write([]byte("id=" + req.PathValue("id")))
+	})
+
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/api/users/42", nil)
+	r.ServeHTTP(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("got status %d, want %d", w.Code, http.StatusOK)
+	}
+	if body := w.Body.String(); body != "id=42" {
+		t.Fatalf("got body %q, want %q", body, "id=42")
+	}
+}
+
+func TestRouter_MiddlewareNotAppliedToOtherRoutes(t *testing.T) {
+	var mwCalled bool
+	mw := func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			mwCalled = true
+			next.ServeHTTP(w, r)
+		})
+	}
+
+	r := server.NewRouter()
+
+	// Add middleware only to /admin group.
+	admin := r.Group("/admin", mw)
+	admin.HandleFunc("GET /dashboard", func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write([]byte("admin"))
+	})
+
+	// Route outside the group.
+	r.HandleFunc("GET /public", func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write([]byte("public"))
+	})
+
+	// Request to /public should NOT trigger group middleware.
+	mwCalled = false
+	w := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/public", nil)
+	r.ServeHTTP(w, req)
+
+	if mwCalled {
+		t.Fatal("group middleware should not be called for routes outside the group")
+	}
+	if w.Body.String() != "public" {
+		t.Fatalf("got body %q, want %q", w.Body.String(), "public")
+	}
 }