What is the usage of golang httptest

In recent years, with the popularity and efficiency of the Golang language, it has attracted more and more attention and love from developers. Golang provides a simple and easy-to-use testing framework, including the httptest library. In this article, I will introduce the basic concepts, usage and precautions of httptest, hoping to help Golang developers in their subsequent testing work.

1. Introduction to httptest

In the Golang testing framework, the main function of httptest is to help testers simulate HTTP requests and responses, so as to easily test the API interface of the server. test. It does not rely on the network and the actual HTTP server, but uses the functions in the net/http package provided by Golang to simulate the entire process of request and response.

2. httptest Common methods

(1) Create a test server

In httptest, we need to create a test server through the NewServer method. The parameters of this method need to be passed in a HandlerFunc that implements the http.Handler interface. For example, we can create a HandlerFunc that handles GET requests and create a test server through it:

func TestGetFoo(t *testing.T) {
    srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        w.WriteHeader(http.StatusOK)
        fmt.Fprintln(w, "Hello, World!")
    }))
    defer srv.Close()

    resp, err := http.Get(srv.URL)
    if err != nil {
        t.Fatal(err)
    }
    defer resp.Body.Close()

    if resp.StatusCode != http.StatusOK {
        t.Errorf("expected %d but got %d", http.StatusOK, resp.StatusCode)
    }
}

(2) Send a request

After we have the test server, we can use the Client to Send a request to the server. Client is an HTTP request client provided by Golang. For example, we can create a HandlerFunc that handles POST requests and create a test server from it. Then send a POST request, containing Json data:

func TestPostJson(t *testing.T) {
    srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        body, _ := ioutil.ReadAll(r.Body)
        w.WriteHeader(http.StatusOK)
        fmt.Fprintln(w, string(body))
    }))
    defer srv.Close()

    payload := struct {
        Name string `json:"name"`
        Age  int    `json:"age"`
    }{
        Name: "Robert",
        Age:  30,
    }
    buf, _ := json.Marshal(payload)
    resp, err := http.Post(srv.URL, "application/json", bytes.NewReader(buf))
    if err != nil {
        t.Fatal(err)
    }
    defer resp.Body.Close()

    if resp.StatusCode != http.StatusOK {
        t.Errorf("expected %d but got %d", http.StatusOK, resp.StatusCode)
    }
    body, _ := ioutil.ReadAll(resp.Body)
    if string(body) != `{"name":"Robert","age":30}` {
        t.Errorf("expected %s but got %s", `{"name":"Robert","age":30}`, string(body))
    }
}

(3) Set the request header and response header

In the test, the request header and response header are also very important parts. We can set request headers and response headers through the Header method. For example, we can create a HandlerFunc that handles GET requests and create a test server from it. Then set the request header and response header:

func TestHeader(t *testing.T) {
    srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        w.Header().Set("X-test", "hello")
        w.WriteHeader(http.StatusOK)
        fmt.Fprintln(w, "Hello, World!")
    }))
    defer srv.Close()

    req, err := http.NewRequest("GET", srv.URL, nil)
    if err != nil {
        t.Fatal(err)
    }
    req.Header.Add("X-test", "world")
    resp, err := http.DefaultClient.Do(req)
    if err != nil {
        t.Fatal(err)
    }
    defer resp.Body.Close()

    if resp.StatusCode != http.StatusOK {
        t.Errorf("expected %d but got %d", http.StatusOK, resp.StatusCode)
    }
    if resp.Header.Get("X-test") != "hello" {
        t.Errorf("expected %s but got %s", "hello", resp.Header.Get("X-test"))
    }
}

(4) Processing HTTPS requests

In actual projects, many HTTP interfaces require secure transmission through HTTPS. In httptest, we can also create a test server that supports HTTPS through the NewTLSServer method. The newly created server uses a self-signed certificate and therefore should not be used in a production environment. For example, we can create a HandlerFunc that handles POST requests and use it to create a test server that supports HTTPS. Then send a POST request containing Json data:

func TestTlsPostJson(t *testing.T) {
    srv := httptest.NewTLSServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        body, _ := ioutil.ReadAll(r.Body)
        w.WriteHeader(http.StatusOK)
        fmt.Fprintln(w, string(body))
    }))
    defer srv.Close()

    payload := struct {
        Name string `json:"name"`
        Age  int    `json:"age"`
    }{
        Name: "Robert",
        Age:  30,
    }
    buf, _ := json.Marshal(payload)
    client := srv.Client()

    resp, err := client.Post(srv.URL, "application/json", bytes.NewReader(buf))
    if err != nil {
        t.Fatal(err)
    }
    defer resp.Body.Close()

    if resp.StatusCode != http.StatusOK {
        t.Errorf("expected %d but got %d", http.StatusOK, resp.StatusCode)
    }
    body, _ := ioutil.ReadAll(resp.Body)
    if string(body) != `{"name":"Robert","age":30}` {
        t.Errorf("expected %s but got %s", `{"name":"Robert","age":30}`, string(body))
    }
}

3. Notes on httptest

Although httptest is very convenient and practical in the Golang testing framework, improper use may still cause Leading to inaccurate test results. We need to pay attention to the following points:

(1) httptest should not be used as an HTTP or HTTPS server in a production environment, only for testing purposes.

(2) If the test server is not shut down properly, resources may be exhausted due to too many test suites.

(3) If the data submitted using httptest does not match the data you submitted, you will not be able to get the correct test results.

4. Summary

In the testing process of Golang, httptest is a very useful tool that can help us simulate HTTP requests and responses, thereby conveniently testing the server-side API. interface for testing. In this article, we introduce the basic concepts, usage and precautions of httptest in detail, hoping to help Golang developers in their subsequent testing work.

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