Docking functions in the Golang to check my http routes

Question

I am completely confused by figuring out how I can mock a function without using any additional packages like golang / mock. I’m just trying to learn this, but I can’t find a lot of decent online resources.

Essentially, I followed this wonderful article , which explains how to use the interface to mock things.

So I rewrote the function that I wanted to test. The function simply inserts some data into the data warehouse. My tests for this are fine - I can mock a function directly.

The problem I'm running into is mocking the "http route I'm trying to verify." I use the Gin structure.

My router (simplified) is as follows:

func SetupRouter() *gin.Engine {

    r := gin.Default()
    r.Use(gin.Logger())
    r.Use(gin.Recovery())

    v1 := r.Group("v1")
    v1.PATCH("operations/:id", controllers.UpdateOperation)
}

What calls the UpdateOperation function:

func UpdateOperation(c *gin.Context) {
    id := c.Param("id")
    r := m.Response{}

    str := m.OperationInfoer{}
    err := m.FindAndCompleteOperation(str, id, r.Report)

    if err == nil {
      c.JSON(200, gin.H{
          "message": "Operation completed",
      })
    }
}

So, I need to make fun of the FindAndCompleteOperation () function.

The main (simplified) functions are as follows:

func (oi OperationInfoer) FindAndCompleteOp(id string, report Report) error {
    ctx := context.Background()
    q := datastore.NewQuery("Operation").
        Filter("Unique_Id =", id).
        Limit(1)

    var ops []Operation

    if ts, err := db.Datastore.GetAll(ctx, q, &ops); err == nil {
        {
            if len(ops) > 0 {
                ops[0].Id = ts[0].ID()
                ops[0].Complete = true

                // Do stuff

                _, err := db.Datastore.Put(ctx, key, &o)
                if err == nil {
                  log.Print("OPERATION COMPLETED")
                }
            }
        }
    }

    err := errors.New("Not found")
    return err
}

func FindAndCompleteOperation(ri OperationInfoer, id string, report Report) error {
    return ri.FindAndCompleteOp(id, report)
}

type OperationInfoer struct{}

To check the route that updates the operation, I have something like this:

FIt("Return 200, updates operation", func() {
    testRouter := SetupRouter()

    param := make(url.Values)
    param["access_token"] = []string{public_token}

    report := m.Report{}
    report.Success = true
    report.Output = "my output"

    jsonStr, _ := json.Marshal(report)
    req, _ := http.NewRequest("PATCH", "/v1/operations/123?"+param.Encode(), bytes.NewBuffer(jsonStr))

    resp := httptest.NewRecorder()
    testRouter.ServeHTTP(resp, req)

    Expect(resp.Code).To(Equal(200))

    o := FakeResponse{}
    json.NewDecoder(resp.Body).Decode(&o)
    Expect(o.Message).To(Equal("Operation completed"))
})

Initially, I tried to trick a little and just tried something like this:

m.FindAndCompleteOperation = func(string, m.Report) error {
  return nil
}

But this affects all other tests, etc.

I hope someone can just explain that the best way to mock the FindAndCompleteOperation function is so that I can test the routes without relying on data storage, etc.

Answer 1

, , :

SetupRouter(), , FindAndCompleteOperation, :

package main

import "github.com/gin-gonic/gin"

// m.Response.Report
type Report struct {
    // ...
}

// m.OperationInfoer
type OperationInfoer struct {
    // ...
}

type findAndComplete func(s OperationInfoer, id string, report Report) error

func FindAndCompleteOperation(OperationInfoer, string, Report) error {
    // ...
    return nil
}

func SetupRouter(f findAndComplete) *gin.Engine {
    r := gin.Default()
    r.Group("v1").PATCH("/:id", func(c *gin.Context) {
        if f(OperationInfoer{}, c.Param("id"), Report{}) == nil {
            c.JSON(200, gin.H{"message": "Operation completed"})
        }
    })
    return r
}

func main() {
    r := SetupRouter(FindAndCompleteOperation)
    if err := r.Run(":8080"); err != nil {
        panic(err)
    }
}

/

package main

import (
    "encoding/json"
    "net/http/httptest"
    "strings"
    "testing"
)

func TestUpdateRoute(t *testing.T) {
    // build findAndComplete stub
    var callCount int
    var lastInfoer OperationInfoer
    var lastID string
    var lastReport Report
    stub := func(s OperationInfoer, id string, report Report) error {
        callCount++
        lastInfoer = s
        lastID = id
        lastReport = report
        return nil // or `fmt.Errorf("Err msg")` if you want to test fault path
    }

    // invoke endpoint
    w := httptest.NewRecorder()
    r := httptest.NewRequest(
        "PATCH",
        "/v1/id_value",
        strings.NewReader(""),
    )
    SetupRouter(stub).ServeHTTP(w, r)

    // check that the stub was invoked correctly
    if callCount != 1 {
        t.Fatal("Wanted 1 call; got", callCount)
    }
    if lastInfoer != (OperationInfoer{}) {
        t.Fatalf("Wanted %v; got %v", OperationInfoer{}, lastInfoer)
    }
    if lastID != "id_value" {
        t.Fatalf("Wanted 'id_value'; got '%s'", lastID)
    }
    if lastReport != (Report{}) {
        t.Fatalf("Wanted %v; got %v", Report{}, lastReport)
    }

    // check that the correct response was returned
    if w.Code != 200 {
        t.Fatal("Wanted HTTP 200; got HTTP", w.Code)
    }

    var body map[string]string
    if err := json.Unmarshal(w.Body.Bytes(), &body); err != nil {
        t.Fatal("Unexpected error:", err)
    }
    if body["message"] != "Operation completed" {
        t.Fatal("Wanted 'Operation completed'; got %s", body["message"])
    }
}

Answer 2

, , . (.. ), .

func (oi OperationInfoer) FindAndCompleteOp(id string, report Report) error {...}

, , .

type OperationInfoer interface {
   FindAndCompleteOp(id string, report Report) error 
} 

type ConcreteOperationInfoer struct { /* actual implementation */ }

func UpdateOperation(oi OperationInfoer) func(c *gin.Context) {
    return func (c *gin.Context){
        // the code
    }
}

:

UpdateOperation(mockOperationInfoer)(ginContext)

type UpdateOperationHandler struct {
    Oi OperationInfoer
}
func (h UpdateOperationHandler ) UpdateOperation (c *gin.Context) {
    h.Oi.FindAndCompleteOp(/* code */ )
}