golang unit testing HOW TO [closed]

Need some direct anwsers which I wont get out of youtube tutorials. This is my controller layer and I wanna do the unit-testing.

1.Question: Do I need to test or only to mock the req.Query() "share, number, singlePrice" and if yes, how do I do this? 2.Question: If I have a function, do I have to test only the input and output values or everything that happens in the function? 3.Question: Could somebody of you give me a full example of how to test this method "CalculateEarning()"?

With LOVE Flaxi

func (stockAPI *StockController) CalculateEarning(req *gin.Context) {

share := req.Query("share")
number := req.Query("number")
singlePrice := req.Query("singlePrice")

if share == "" || number == "" || singlePrice == "" {
    req.JSON(http.StatusBadRequest, "bad request")
    return
} else {
    var responseEntity dto.OutputDTO
    var stockError *customError.ErrorStock

    responseEntity.Share = share
    responseEntity.Numbers, _ = strconv.ParseFloat(strings.Replace(number, ",", ".", 1), 64)
    responseEntity.Price, _ = strconv.ParseFloat(strings.Replace(singlePrice, ",", ".", 1), 64)

    key := req.GetHeader("x-rapidapi-key")

    ret, err := stockAPI.stockService.CalculateEarning(key, responseEntity)

    if errors.As(err, &stockError) {
        if stockError.Code == 200 {
            req.JSON(http.StatusOK, ret)
        } else if stockError.Code == 204 {
            req.JSON(http.StatusNoContent, stockError.Text)
        } else if stockError.Code == 401 {
            req.JSON(http.StatusUnauthorized, stockError.Text)
        } else if stockError.Code == 403 {
            req.JSON(http.StatusForbidden, stockError.Text)
        } else if stockError.Code == 500 {
            req.JSON(http.StatusInternalServerError, stockError.Text)
        }
    }
}

}