如何在 Go 中为使用 App Engine 服务的代码运行单元测试

package myapp

import (
    "context"
    "net/http"
    "net/http/httptest"
    "testing"

    "github.com/icub3d/appenginetesting"
    "google.golang.org/appengine/datastore"
)

// 定义一个简单的结构体，用于存储到 Datastore
type MyData struct {
    Name string
}

// 一个使用 Datastore 的函数
func SaveData(ctx context.Context, name string) error {
    key := datastore.NewIncompleteKey(ctx, "MyData", nil)
    data := MyData{Name: name}
    _, err := datastore.Put(ctx, key, &data)
    return err
}

// 测试 SaveData 函数
func TestSaveData(t *testing.T) {
    // 创建一个模拟的 App Engine 上下文
    ctx, err := appenginetesting.NewContext(nil)
    if err != nil {
        t.Fatalf("Failed to create context: %v", err)
    }
    defer ctx.Close()

    // 调用 SaveData 函数
    err = SaveData(ctx, "Test Name")
    if err != nil {
        t.Fatalf("SaveData failed: %v", err)
    }

    // 验证数据是否已保存到 Datastore
    q := datastore.NewQuery("MyData")
    var results []MyData
    _, err = q.GetAll(ctx, &results)
    if err != nil {
        t.Fatalf("Failed to query Datastore: %v", err)
    }

    if len(results) != 1 {
        t.Fatalf("Expected 1 result, got %d", len(results))
    }

    if results[0].Name != "Test Name" {
        t.Fatalf("Expected name 'Test Name', got '%s'", results[0].Name)
    }
}

// 使用模拟上下文处理 HTTP 请求的例子
func myHandler(w http.ResponseWriter, r *http.Request) {
    ctx := appenginetesting.MustContext(r) // 从请求中获取模拟的 App Engine 上下文
    err := SaveData(ctx, "Request Name")
    if err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }
    w.WriteHeader(http.StatusOK)
}

func TestMyHandler(t *testing.T) {
    ctx, err := appenginetesting.NewContext(nil)
    if err != nil {
        t.Fatalf("Failed to create context: %v", err)
    }
    defer ctx.Close()

    req := httptest.NewRequest("GET", "/", nil)
    req = req.WithContext(ctx) // 将模拟的上下文添加到请求中

    w := httptest.NewRecorder()
    myHandler(w, req)

    if w.Code != http.StatusOK {
        t.Fatalf("Handler returned wrong status code: got %v want %v",
            w.Code, http.StatusOK)
    }

    q := datastore.NewQuery("MyData")
    var results []MyData
    _, err = q.GetAll(ctx, &results)
    if err != nil {
        t.Fatalf("Failed to query Datastore: %v", err)
    }

    if len(results) != 1 {
        t.Fatalf("Expected 1 result, got %d", len(results))
    }

    if results[0].Name != "Request Name" {
        t.Fatalf("Expected name 'Request Name', got '%s'", results[0].Name)
    }
}