unit-testing - 进行单元测试-样板

Question

这是我的Todo应用程序的基本结构，看起来像是“main.go”；

package main

import (
    "encoding/json"
    "fmt"
    "log"
    "net/http"
    "github.com/gorilla/mux"
)

//  Todo Struct (Model)
type Todo struct {
    Id        string `json:"id"`
    Task      string `json:"task"`
    Completed bool   `json:"completed"`
}

var todos []Todo

//  Get All Todos
func GetTodos(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Type", "application/json")
    json.NewEncoder(w).Encode(todos)
}

func main() {
    // Init Router
    r := mux.NewRouter()

    // Mock Data
    todos = append(todos, Todo{Id: "1", Task: "FirstTask", Completed: false})
    todos = append(todos, Todo{Id: "2", Task: "SecondTask", Completed: false})

    fmt.Println("Go dude dude go ")

    r.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        fmt.Fprint(w, "Hello dudes")
    })

    r.HandleFunc("/api/todos", GetTodos).Methods("GET")

    log.Fatal(http.ListenAndServe(":8080", r))
}

这是我的“main_test.go”

package main

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

func TestGetTodos(t *testing.T) {
    req, err := http.NewRequest("GET", "/api/todos", nil)
    if err != nil {
        t.Fatal(err)
    }
    rr := httptest.NewRecorder()
    handler := http.HandlerFunc(GetTodos)
    handler.ServeHTTP(rr, req)
    if status := rr.Code; status != http.StatusOK {
        t.Errorf("handler returned wrong status code: got %v want %v",
            status, http.StatusOK)
    }

    // Check the response body is what we expect.
    expected := `[{Id: "1", Task: "FirstTask", Completed: false},{Id: "2", Task: "SecondTask", Completed: false}]`
    if rr.Body.String() != expected {
        t.Errorf("handler returned unexpected body: got %v want %v",
            rr.Body.String(), expected)
    }
}

问题出在这里，我不断收到以下错误；

--- FAIL: TestGetTodos (0.00s)
    main_test.go:25: handler returned unexpected body: got null
         want [{Id: "1", Task: "FirstTask", Completed: false},{Id: "2", Task: "SecondTask", Completed: false}]
FAIL
exit status 1
FAIL   ..filesPath/backend   0.213s 

我肯定错过了这么简单，但无法弄清楚。

Answer 1

在运行测试运行时，永远不会调用main，因此todos为空。

var todos []Todo

这就是 rr.Body.String()返回null的原因
如果将模拟数据生成代码移动到正在测试的 GetTodos函数中

var todos []Todo

//  Get All Todos
func GetTodos(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Type", "application/json")
    var mockTodos []Todo
    mockTodos = append(mockTodos, Todo{Id: "1", Task: "FirstTask", Completed: false})
    mockTodos = append(mockTodos, Todo{Id: "2", Task: "SecondTask", Completed: false})
    json.NewEncoder(w).Encode(mockTodos)
}

测试仍然会失败，但是主体将不再为null而是显示

=== RUN   TestGetTodos
TestGetTodos: main_test.go:25: handler returned unexpected body: got [{"id":"1","task":"FirstTask","completed":false},{"id":"2","task":"SecondTask","completed":false}]
     want [{Id: "1", Task: "FirstTask", Completed: false},{Id: "2", Task: "SecondTask", Completed: false}]
--- FAIL: TestGetTodos (0.00s)
FAIL

那是因为您的期望不是正确的json格式。如果您更换

expected := `[{Id: "1", Task: "FirstTask", Completed: false},{Id: "2", Task: "SecondTask", Completed: false}]`

与

expected := "[{\"id\":\"1\",\"task\":\"FirstTask\",\"completed\":false},{\"id\":\"2\",\"task\":\"SecondTask\",\"completed\":false}]\n"

那将帮助您通过测试。
我在预期字符串的末尾添加了换行符 \n，因为 json.NewEncoder(w).Encode(todos)在输出中添加了换行符

理想情况下，您不想使用全局变量来存储状态。您将拥有另一个可以存储状态或为您检索状态的对象(可能是从DB)。在测试中，您将使用状态初始化该对象，然后检查函数是否以该状态作为输入正确执行。
以下是 下一步可以做什么的简单示例。 main.go

//  Todo Struct (Model)
type Todo struct {
    Id        string `json:"id"`
    Task      string `json:"task"`
    Completed bool   `json:"completed"`
}

type App struct {
    todos []Todo
}

//  Get All Todos
func (a *App) GetTodos(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Type", "application/json")
    json.NewEncoder(w).Encode(a.todos)
}

func main() {
    // Init Router
    r := mux.NewRouter()

    // Mock Data
    app := App{todos: []Todo{
        {Id: "1", Task: "FirstTask", Completed: false},
        {Id: "2", Task: "SecondTask", Completed: false},
    }}

    fmt.Println("Go dude dude go ")

    r.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        fmt.Fprint(w, "Hello dudes")
    })

    r.HandleFunc("/api/todos", app.GetTodos).Methods("GET")

    log.Fatal(http.ListenAndServe(":8080", r))
}

main_test.go

func TestGetTodos(t *testing.T) {
    req, err := http.NewRequest("GET", "/api/todos", nil)
    if err != nil {
        t.Fatal(err)
    }

    // Mock Data
    app := App{todos: []Todo{
        {Id: "1", Task: "FirstTask", Completed: false},
        {Id: "2", Task: "SecondTask", Completed: false},
    }}

    rr := httptest.NewRecorder()
    handler := http.HandlerFunc(app.GetTodos)
    handler.ServeHTTP(rr, req)
    if status := rr.Code; status != http.StatusOK {
        t.Errorf("handler returned wrong status code: got %v want %v",
            status, http.StatusOK)
    }

    // Check the response body is what we expect.
    expected := "[{\"id\":\"1\",\"task\":\"FirstTask\",\"completed\":false},{\"id\":\"2\",\"task\":\"SecondTask\",\"completed\":false}]\n"
    str := rr.Body.String()
    if diff := cmp.Diff(expected , str); diff != "" {
        t.Errorf("%s: mismatch (-want +got):\n%s", "", diff)
    }
    if str != expected {
        t.Errorf("handler returned unexpected body: got %v want %v",
            rr.Body.String(), expected)
    }
}