Go testcases for REST server

Question

`Hi , I am new to Go and writing Testcases in Go . I have a REST server where all the data are retrieved from POST method. I am trying to write a test for methods but I am getting errors while testing.

func (r *Rest) GetToken(c *gin.Context) {
    log.Println("--- PROD : GET TOKEN called ---")
    data, err := ioutil.ReadAll(c.Request.Body)
    if err != nil {
        c = services.SendError(err, "10001", r.errorMsgList, c)
        return
    }
    var jsonData entities.GetTokenRequest
    e := json.Unmarshal(data, &jsonData)
    if e != nil {
        log.Println(e)
        c = services.SendError(e, "10002", r.errorMsgList, c)
        return
    }
    log.Println(jsonData)
    res, err := r.cs.GetToken(jsonData)
`
    if err == nil {
        c.JSON(http.StatusOK, res)
        return
    } else {
        c=services.SendError(err, "10003",r.errorMsgList, c)
        return
    }
}

func TestTokenHandler(t *testing.T) {
    r := SetUpRouter()
    reqBody, _ := mock.GetTokenRequestJson(testConfig.TokenPayload)
    r.POST(testConfig.RouteList.CreateTokenApi, restService.TokenHandle)
    req, _ := http.NewRequest("POST", testConfig.RouteList.CreateTokenApi, strings.NewReader(reqBody))
    w := httptest.NewRecorder()
    r.ServeHTTP(w, req)
    assert.Equal(t, http.StatusOK, w.Code)
    responseBody, _ := ioutil.ReadAll(w.Body)
    `var tokenResponse entities.TokenResponse
    `err := json.Unmarshal(responseBody, &tokenResponse)`
    if err != nil {
        return
    }
    `assert.NotEmpty`(t, tokenResponse.Data.CreateServiceTokenResponse_1.Token, "Failed to generate token")`
}