tsweb: JSONHandler using reflect (#437)

Updates #395 #437

Signed-off-by: Zijie Lu <zijie@tailscale.com>

tsweb/jsonhandler_test.go

@@ -0,0 +1,175 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package tsweb
+
+import (
+	"encoding/json"
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+type Data struct {
+	Name  string
+	Price int
+}
+
+type Response struct {
+	Status string
+	Error  string
+	Data   *Data
+}
+
+func TestNewJSONHandler(t *testing.T) {
+	checkStatus := func(w *httptest.ResponseRecorder, status string) *Response {
+		d := &Response{
+			Data: &Data{},
+		}
+
+		t.Logf("%s", w.Body.Bytes())
+		err := json.Unmarshal(w.Body.Bytes(), d)
+		if err != nil {
+			t.Logf(err.Error())
+			return nil
+		}
+
+		if d.Status == status {
+			t.Logf("ok: %s", d.Status)
+		} else {
+			t.Fatalf("wrong status: %s %s", d.Status, status)
+		}
+
+		return d
+	}
+
+	// 2 1
+	h21 := JSONHandler(func(w http.ResponseWriter, r *http.Request) error {
+		return nil
+	})
+
+	t.Run("2 1 simple", func(t *testing.T) {
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest("GET", "/", nil)
+		h21.ServeHTTP(w, r)
+		checkStatus(w, "success")
+	})
+
+	// 2 2
+	h22 := JSONHandler(func(w http.ResponseWriter, r *http.Request) (*Data, error) {
+		return &Data{Name: "tailscale"}, nil
+	})
+	t.Run("2 2 get data", func(t *testing.T) {
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest("GET", "/", nil)
+		h22.ServeHTTP(w, r)
+		checkStatus(w, "success")
+	})
+
+	// 3 1
+	h31 := JSONHandler(func(w http.ResponseWriter, r *http.Request, d *Data) error {
+		if d.Name == "" {
+			return errors.New("name is empty")
+		}
+
+		return nil
+	})
+	t.Run("3 1 post data", func(t *testing.T) {
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest("POST", "/", strings.NewReader(`{"Name": "tailscale"}`))
+		h31.ServeHTTP(w, r)
+		checkStatus(w, "success")
+	})
+
+	t.Run("3 1 bad json", func(t *testing.T) {
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest("POST", "/", strings.NewReader(`{`))
+		h31.ServeHTTP(w, r)
+		checkStatus(w, "error")
+	})
+
+	t.Run("3 1 post data error", func(t *testing.T) {
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest("POST", "/", strings.NewReader(`{}`))
+		h31.ServeHTTP(w, r)
+		resp := checkStatus(w, "error")
+		if resp.Error != "name is empty" {
+			t.Fatalf("wrong error")
+		}
+	})
+
+	// 3 2
+	h32 := JSONHandler(func(w http.ResponseWriter, r *http.Request, d *Data) (*Data, error) {
+		if d.Price == 0 {
+			return nil, errors.New("price is empty")
+		}
+
+		return &Data{Price: d.Price * 2}, nil
+	})
+	t.Run("3 2 post data", func(t *testing.T) {
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest("POST", "/", strings.NewReader(`{"Price": 10}`))
+		h32.ServeHTTP(w, r)
+		resp := checkStatus(w, "success")
+		t.Log(resp.Data)
+		if resp.Data.Price != 20 {
+			t.Fatalf("wrong price: %d %d", resp.Data.Price, 10)
+		}
+	})
+
+	t.Run("3 2 post data error", func(t *testing.T) {
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest("POST", "/", strings.NewReader(`{}`))
+		h32.ServeHTTP(w, r)
+		resp := checkStatus(w, "error")
+		if resp.Error != "price is empty" {
+			t.Fatalf("wrong error")
+		}
+	})
+
+	// fn check
+	shouldPanic := func() {
+		r := recover()
+		if r == nil {
+			t.Fatalf("should panic")
+		}
+		t.Log(r)
+	}
+
+	t.Run("2 0 panic", func(t *testing.T) {
+		defer shouldPanic()
+		JSONHandler(func(w http.ResponseWriter, r *http.Request) {})
+	})
+
+	t.Run("2 1 panic return value", func(t *testing.T) {
+		defer shouldPanic()
+		JSONHandler(func(w http.ResponseWriter, r *http.Request) string {
+			return ""
+		})
+	})
+
+	t.Run("2 1 panic arguments", func(t *testing.T) {
+		defer shouldPanic()
+		JSONHandler(func(r *http.Request, w http.ResponseWriter) error {
+			return nil
+		})
+	})
+
+	t.Run("3 1 panic arguments", func(t *testing.T) {
+		defer shouldPanic()
+		JSONHandler(func(name string, r *http.Request, w http.ResponseWriter) error {
+			return nil
+		})
+	})
+
+	t.Run("3 2 panic return value", func(t *testing.T) {
+		defer shouldPanic()
+		//lint:ignore ST1008 intentional
+		JSONHandler(func(name string, r *http.Request, w http.ResponseWriter) (error, string) {
+			return nil, "panic"
+		})
+	})
+}