httptestでmock server的なものを作る方法のメモ

以下の3つが欲しい

• get
• post (form)
• post (json)

package m

import (
    "bytes"
    "encoding/json"
    "net/http"
    "net/http/httptest"
    "net/url"
    "testing"

    "io/ioutil"

    "github.com/pkg/errors"
    "github.com/stretchr/testify/assert"
    "github.com/stretchr/testify/require"
)

func TestGet(t *testing.T) {
    ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        assert.Exactly(t, "/foo", r.URL.Path)
        assert.Exactly(t, "1", r.URL.Query().Get("value"))
    }))
    defer ts.Close()

    _, err := http.Get(ts.URL + "/foo?value=1")
    require.NoError(t, err)
}

func TestPost(t *testing.T) {
    ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        assert.Exactly(t, "/foo", r.URL.Path)
        r.ParseForm()
        assert.Exactly(t, "1", r.Form.Get("value"))
    }))
    defer ts.Close()
    values := url.Values{}
    values.Add("value", "1")
    _, err := http.PostForm(ts.URL+"/foo", values)
    require.NoError(t, err)
}

func TestPostJSON(t *testing.T) {
    type data struct {
        Name string `json:"name"`
        Age  int    `json:"int"`
    }

    ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        assert.Exactly(t, "/foo", r.URL.Path)
        var val data
        parseJSONRequest(r, func(b []byte) error {
            return json.Unmarshal(b, &val)
        })
        assert.Exactly(t, "foo", val.Name)
        assert.Exactly(t, 20, val.Age)
    }))
    defer ts.Close()

    dataset := data{
        Name: "foo",
        Age:  20,
    }

    b, err := json.Marshal(dataset)
    require.NoError(t, err)
    req, err := http.NewRequest("POST", ts.URL+"/foo", bytes.NewBuffer(b))
    req.Header.Set("Content-Type", "application/json")

    _, err = (&http.Client{}).Do(req)
    require.NoError(t, err)
}

func parseJSONRequest(r *http.Request, parse func(body []byte) error) error {
    if r.Body == nil {
        return errors.New("missing form body")
    }
    ct := r.Header.Get("Content-Type")
    if ct != "application/json" {
        return errors.Errorf("invalid content type: %v", ct)
    }
    b, err := ioutil.ReadAll(r.Body)
    if err != nil {
        return err
    }
    return parse(b)
}