From 474ebc08017921d5b1a3cf16d312b1cc91732334 Mon Sep 17 00:00:00 2001
From: oabrivard <olivier@abrivard.fr>
Date: Sat, 7 Feb 2026 23:59:45 +0100
Subject: [PATCH] Finished Task 8: Infra Utils

---
 backend/shared/infra/utils/httputil/errors.go |  8 ++++--
 .../infra/utils/httputil/errors_test.go       | 26 +++++++++++++++++++
 .../infra/utils/validation/validator.go       | 16 +++++++++++-
 .../infra/utils/validation/validator_test.go  |  1 +
 4 files changed, 48 insertions(+), 3 deletions(-)

diff --git a/backend/shared/infra/utils/httputil/errors.go b/backend/shared/infra/utils/httputil/errors.go
index c6a77bd..7681a75 100644
--- a/backend/shared/infra/utils/httputil/errors.go
+++ b/backend/shared/infra/utils/httputil/errors.go
@@ -2,6 +2,9 @@
 package httputil
 
 import (
+	stderrors "errors"
+	"strconv"
+
 	"github.com/gofiber/fiber/v3"
 
 	"knowfoolery/backend/shared/domain/errors"
@@ -41,7 +44,8 @@ func MapError(err error) (int, ErrorResponse) {
 		)
 	}
 
-	domainErr, ok := err.(*errors.DomainError)
+	var domainErr *errors.DomainError
+	ok := stderrors.As(err, &domainErr)
 	if !ok {
 		return fiber.StatusInternalServerError, NewErrorResponse(
 			"INTERNAL",
@@ -131,7 +135,7 @@ func Conflict(c fiber.Ctx, message string) error {
 
 // TooManyRequests sends a 429 Too Many Requests response.
 func TooManyRequests(c fiber.Ctx, message string, retryAfter int) error {
-	c.Set("Retry-After", string(rune(retryAfter)))
+	c.Set("Retry-After", strconv.Itoa(retryAfter))
 	return c.Status(fiber.StatusTooManyRequests).JSON(NewErrorResponse(
 		"RATE_LIMIT_EXCEEDED",
 		message,
diff --git a/backend/shared/infra/utils/httputil/errors_test.go b/backend/shared/infra/utils/httputil/errors_test.go
index 5285ccf..a15a6e2 100644
--- a/backend/shared/infra/utils/httputil/errors_test.go
+++ b/backend/shared/infra/utils/httputil/errors_test.go
@@ -5,6 +5,7 @@ package httputil
 import (
 	"encoding/json"
 	"errors"
+	"fmt"
 	"net/http"
 	"net/http/httptest"
 	"testing"
@@ -116,3 +117,28 @@ func TestSendError(t *testing.T) {
 	require.NoError(t, json.NewDecoder(resp.Body).Decode(&body))
 	require.Equal(t, "NOT_FOUND", body.Code)
 }
+
+// TestMapError_WrappedDomainError verifies wrapped domain errors are recognized.
+func TestMapError_WrappedDomainError(t *testing.T) {
+	wrapped := fmt.Errorf("outer: %w", errorspkg.New(errorspkg.CodeValidationFailed, "bad input"))
+	status, resp := MapError(wrapped)
+	require.Equal(t, http.StatusBadRequest, status)
+	require.Equal(t, errorspkg.CodeValidationFailed.String(), resp.Code)
+	require.Equal(t, "bad input", resp.Message)
+}
+
+// TestTooManyRequestsRetryAfterHeader verifies Retry-After is set as a decimal string.
+func TestTooManyRequestsRetryAfterHeader(t *testing.T) {
+	app := fiber.New()
+	app.Get("/", func(c fiber.Ctx) error {
+		return TooManyRequests(c, "slow down", 120)
+	})
+
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	resp, err := app.Test(req)
+	require.NoError(t, err)
+	defer resp.Body.Close()
+
+	require.Equal(t, http.StatusTooManyRequests, resp.StatusCode)
+	require.Equal(t, "120", resp.Header.Get("Retry-After"))
+}
diff --git a/backend/shared/infra/utils/validation/validator.go b/backend/shared/infra/utils/validation/validator.go
index 6437375..3208793 100644
--- a/backend/shared/infra/utils/validation/validator.go
+++ b/backend/shared/infra/utils/validation/validator.go
@@ -82,7 +82,21 @@ func (v *Validator) ValidateVar(field interface{}, tag string) error {
 		return nil
 	}
 
-	return errors.Wrap(errors.CodeValidationFailed, "validation failed", err)
+	validationErrors, ok := err.(validator.ValidationErrors)
+	if !ok {
+		return errors.Wrap(errors.CodeValidationFailed, "validation failed", err)
+	}
+
+	messages := make([]string, 0, len(validationErrors))
+	for _, e := range validationErrors {
+		messages = append(messages, formatValidationError(e))
+	}
+
+	return errors.Wrap(
+		errors.CodeValidationFailed,
+		strings.Join(messages, "; "),
+		nil,
+	)
 }
 
 // formatValidationError formats a single validation error into a readable message.
diff --git a/backend/shared/infra/utils/validation/validator_test.go b/backend/shared/infra/utils/validation/validator_test.go
index adf5064..5c8ab6d 100644
--- a/backend/shared/infra/utils/validation/validator_test.go
+++ b/backend/shared/infra/utils/validation/validator_test.go
@@ -50,6 +50,7 @@ func TestValidator_ValidateVarReturnsDomainError(t *testing.T) {
 	var domainErr *errs.DomainError
 	require.ErrorAs(t, err, &domainErr)
 	require.Equal(t, errs.CodeValidationFailed, domainErr.Code)
+	require.Contains(t, domainErr.Message, "must be a valid email")
 }
 
 // TestValidator_JSONTagNameMapping ensures JSON tag names appear in validation error text.