Question

我有一些中间件，可以在请求中添加带有请求ID的上下文。

func AddContextWithRequestID(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    var ctx context.Context
    ctx = NewContextWithRequestID(ctx, r)
    next.ServeHTTP(w, r.WithContext(ctx))
})}

如何为此编写测试？

Answer 1

要进行测试，您需要运行传入请求的处理程序，并使用一个自定义next处理程序来检查请求是否确实被修改。

您可以如下创建该处理程序：

（我假设您的NewContextWithRequestID向请求中添加了一个“ reqId”键，其值为“ 1234”，您当然应该根据需要修改断言）

// create a handler to use as "next" which will verify the request
nextHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    val := r.Context().Value("reqId")
    if val == nil {
        t.Error("reqId not present")
    }
    valStr, ok := val.(string)
    if !ok {
        t.Error("not string")
    }
    if valStr != "1234" {
        t.Error("wrong reqId")
    }
})

然后您可以将该处理程序用作您的next：

// create the handler to test, using our custom "next" handler
handlerToTest := AddContextWithRequestID(nextHandler)

然后调用该处理程序：

// create a mock request to use
req := httptest.NewRequest("GET", "http://testing", nil)
// call the handler using a mock response recorder (we'll not use that anyway)
handlerToTest.ServeHTTP(httptest.NewRecorder(), req)

将所有内容放在一起作为工作测试，这就是下面的代码。

注意：我修复了您原始的“ AddContextWithRequestID”中的一个小错误，因为当您未经初始化就声明时，ctx值以nil开头。

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

func NewContextWithRequestID(ctx context.Context, r *http.Request) context.Context {
    return context.WithValue(ctx, "reqId", "1234")
}

func AddContextWithRequestID(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        var ctx = context.Background()
        ctx = NewContextWithRequestID(ctx, r)
        next.ServeHTTP(w, r.WithContext(ctx))
    })
}

func TestIt(t *testing.T) {

    // create a handler to use as "next" which will verify the request
    nextHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        val := r.Context().Value("reqId")
        if val == nil {
            t.Error("reqId not present")
        }
        valStr, ok := val.(string)
        if !ok {
            t.Error("not string")
        }
        if valStr != "1234" {
            t.Error("wrong reqId")
        }
    })

    // create the handler to test, using our custom "next" handler
    handlerToTest := AddContextWithRequestID(nextHandler)

    // create a mock request to use
    req := httptest.NewRequest("GET", "http://testing", nil)

    // call the handler using a mock response recorder (we'll not use that anyway)
    handlerToTest.ServeHTTP(httptest.NewRecorder(), req)
}

测试修改请求的golang中间件

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