test: expand test coverage across diary, product, savedrecipe, ingredient, menu, recognition

- Fix locale_test: add TestMain to pre-populate Supported map so zh/es tests pass
- Export pure functions for testability: ResolveWeekStart, MapCuisineSlug (menu + savedrecipe), MergeAndDeduplicate
- Introduce repository interfaces (DiaryRepository, ProductRepository, SavedRecipeRepository, IngredientSearcher) in each handler; NewHandler now accepts interfaces — concrete *Repository still satisfies them
- Add mock files: diary/mocks, product/mocks, savedrecipe/mocks
- Add handler unit tests (no DB) for diary (8), product (8), savedrecipe (8), ingredient (5)
- Add pure-function unit tests: menu/ResolveWeekStart (6), savedrecipe/MapCuisineSlug (5), recognition/MergeAndDeduplicate (6)
- Add repository integration tests (//go:build integration): diary (4), product (6)
- Extend recipe integration tests: GetByID_Found, GetByID_WithTranslation

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/internal/domain/savedrecipe/handler.go

@@ -1,6 +1,7 @@
 package savedrecipe
 
 import (
+	"context"
 	"encoding/json"
 	"errors"
 	"log/slog"
@@ -12,13 +13,21 @@ import (
 
 const maxBodySize = 1 << 20 // 1 MB
 
+// SavedRecipeRepository is the data layer interface used by Handler.
+type SavedRecipeRepository interface {
+	Save(ctx context.Context, userID string, req SaveRequest) (*UserSavedRecipe, error)
+	List(ctx context.Context, userID string) ([]*UserSavedRecipe, error)
+	GetByID(ctx context.Context, userID, id string) (*UserSavedRecipe, error)
+	Delete(ctx context.Context, userID, id string) error
+}
+
 // Handler handles HTTP requests for saved recipes.
 type Handler struct {
-	repo *Repository
+	repo SavedRecipeRepository
 }
 
 // NewHandler creates a new Handler.
-func NewHandler(repo *Repository) *Handler {
+func NewHandler(repo SavedRecipeRepository) *Handler {
 	return &Handler{repo: repo}
 }
 

backend/internal/domain/savedrecipe/mocks/repository.go

@@ -0,0 +1,31 @@
+package mocks
+
+import (
+	"context"
+
+	"github.com/food-ai/backend/internal/domain/savedrecipe"
+)
+
+// MockSavedRecipeRepository is a test double implementing savedrecipe.SavedRecipeRepository.
+type MockSavedRecipeRepository struct {
+	SaveFn     func(ctx context.Context, userID string, req savedrecipe.SaveRequest) (*savedrecipe.UserSavedRecipe, error)
+	ListFn     func(ctx context.Context, userID string) ([]*savedrecipe.UserSavedRecipe, error)
+	GetByIDFn  func(ctx context.Context, userID, id string) (*savedrecipe.UserSavedRecipe, error)
+	DeleteFn   func(ctx context.Context, userID, id string) error
+}
+
+func (m *MockSavedRecipeRepository) Save(ctx context.Context, userID string, req savedrecipe.SaveRequest) (*savedrecipe.UserSavedRecipe, error) {
+	return m.SaveFn(ctx, userID, req)
+}
+
+func (m *MockSavedRecipeRepository) List(ctx context.Context, userID string) ([]*savedrecipe.UserSavedRecipe, error) {
+	return m.ListFn(ctx, userID)
+}
+
+func (m *MockSavedRecipeRepository) GetByID(ctx context.Context, userID, id string) (*savedrecipe.UserSavedRecipe, error) {
+	return m.GetByIDFn(ctx, userID, id)
+}
+
+func (m *MockSavedRecipeRepository) Delete(ctx context.Context, userID, id string) error {
+	return m.DeleteFn(ctx, userID, id)
+}

backend/internal/domain/savedrecipe/repository.go

@@ -34,7 +34,7 @@ func (r *Repository) Save(ctx context.Context, userID string, req SaveRequest) (
 		cr := dish.CreateRequest{
 			Name:        req.Title,
 			Description: req.Description,
-			CuisineSlug: mapCuisineSlug(req.Cuisine),
+			CuisineSlug: MapCuisineSlug(req.Cuisine),
 			ImageURL:    req.ImageURL,
 			Source:      req.Source,
 			Difficulty:  req.Difficulty,
@@ -373,9 +373,9 @@ func scanUSR(s rowScanner) (*UserSavedRecipe, error) {
 	return &r, err
 }
 
-// mapCuisineSlug maps a free-form cuisine string (from Gemini) to a known slug.
+// MapCuisineSlug maps a free-form cuisine string (from Gemini) to a known slug.
 // Falls back to "other".
-func mapCuisineSlug(cuisine string) string {
+func MapCuisineSlug(cuisine string) string {
 	known := map[string]string{
 		"russian":       "russian",
 		"italian":       "italian",