Testing POST request with Echo (expected vs actual output)

Question

I'm kinda new in Go, so, sorry if this is a silly question.

I have been recently trying some API with Echo. I'm trying to test a route(POST) handler of Go echo that gets a json and puts it in an array. Bellow is the code for the handler main.go and for the test test_main.go

main.go

type Houses struct {
Name    string `json:"name,ommitempty"`
Address string `json:"address,omitempty"`
}

var houses []Houses

func newHouse(c echo.Context) error {
    m := echo.Map{}
    if err := c.Bind(&m); err != nil {
        return err
    }
    dv := Houses{
        Name:    m["name"].(string),
        Address: m["address"].(string),
    }
    houses = append(houses, dv)
    js, _ := json.Marshal(houses)
    fmt.Println(fmt.Sprintf("%s", js))

    return c.JSON(http.StatusOK, string(js))
}

test_main.go

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

    "github.com/labstack/echo"
    "github.com/stretchr/testify/assert"
)

var userJSON = `{"name":"Jhon Doe","address":"High St."}`

func TestModel(t *testing.T) {
    url := "/new_house"
    e := echo.New()
    req, err := http.NewRequest(http.MethodPost, url, strings.NewReader(userJSON))
    req.Header.Set("Content-Type", "application/json")
    if err != nil {
        t.Errorf("The request could not be created because of: %v", err)
    }
    rec := httptest.NewRecorder()
    c := e.NewContext(req, rec)
    // c.SetPath("/new_house")
    // c.JSON(http.StatusOK, Devices{"Jhon Doe", "Middle Way"})

    res := rec.Result()
    defer res.Body.Close()

    if assert.NoError(t, newHouse(c)) {
        assert.Equal(t, http.StatusOK, rec.Code)
        assert.Equal(t, "["+userJSON+"]", rec.Body.String())
    }
}

The test fails with the error shown bellow even though the handler works properly if called by curl.

[{"name":"Jhon Doe","address":"High St."}]
--- FAIL: TestModel (0.00s)
    /home/gaidaros/Code/echo-badger/models/model_test.go:34: 
            Error Trace:    model_test.go:34
            Error:          Not equal: 
                            expected: "[{\"name\":\"Jhon Doe\",\"address\":\"High St.\"}]"
                            actual  : "\"[{\\\"name\\\":\\\"Jhon Doe\\\",\\\"address\\\":\\\"High St.\\\"}]\""

                            Diff:
                            --- Expected
                            +++ Actual
                            @@ -1 +1 @@
                            -[{"name":"Jhon Doe","address":"High St."}]
                            +"[{\"name\":\"Jhon Doe\",\"address\":\"High St.\"}]"
            Test:           TestModel
FAIL
exit status 1

After several days of struggling over it I couldn't figure out how to make the actual output to match the expected, so I'm posting here in hopes of getting past this obstacle. Any help is appreciated!

Answer 1

You are calling json.Marshal on the []Houses, which marshals it to a JSON string, then you are calling echo.Context.JSON with the JSON string, which internally calls json.Marshal. Double marshalling causes the escaping. See example. (error checking omitted for brevity)

https://play.golang.org/p/nYvHS4huy0M

h := &Houses{"Jhon Doe", "High St."}
d, _ := json.Marshal(h)

// double marshal bad
d, _ = json.Marshal(string(d))

fmt.Println(string(d))
// prints "{\"name\":\"Jhon Doe\",\"address\":\"High St.\"}"

Your solution is to just pass the slice to your c.JSON call. As a side note, you should be able to pass the struct to c.Bind instead of using a map with type assertions.