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/diary/handler.go

@@ -1,6 +1,7 @@
 package diary
 
 import (
+	"context"
 	"encoding/json"
 	"log/slog"
 	"net/http"
@@ -9,13 +10,20 @@ import (
 	"github.com/go-chi/chi/v5"
 )
 
+// DiaryRepository is the data layer interface used by Handler.
+type DiaryRepository interface {
+	ListByDate(ctx context.Context, userID, date string) ([]*Entry, error)
+	Create(ctx context.Context, userID string, req CreateRequest) (*Entry, error)
+	Delete(ctx context.Context, id, userID string) error
+}
+
 // Handler handles diary endpoints.
 type Handler struct {
-	repo *Repository
+	repo DiaryRepository
 }
 
 // NewHandler creates a new Handler.
-func NewHandler(repo *Repository) *Handler {
+func NewHandler(repo DiaryRepository) *Handler {
 	return &Handler{repo: repo}
 }
 

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

@@ -0,0 +1,26 @@
+package mocks
+
+import (
+	"context"
+
+	"github.com/food-ai/backend/internal/domain/diary"
+)
+
+// MockDiaryRepository is a test double implementing diary.DiaryRepository.
+type MockDiaryRepository struct {
+	ListByDateFn func(ctx context.Context, userID, date string) ([]*diary.Entry, error)
+	CreateFn     func(ctx context.Context, userID string, req diary.CreateRequest) (*diary.Entry, error)
+	DeleteFn     func(ctx context.Context, id, userID string) error
+}
+
+func (m *MockDiaryRepository) ListByDate(ctx context.Context, userID, date string) ([]*diary.Entry, error) {
+	return m.ListByDateFn(ctx, userID, date)
+}
+
+func (m *MockDiaryRepository) Create(ctx context.Context, userID string, req diary.CreateRequest) (*diary.Entry, error) {
+	return m.CreateFn(ctx, userID, req)
+}
+
+func (m *MockDiaryRepository) Delete(ctx context.Context, id, userID string) error {
+	return m.DeleteFn(ctx, id, userID)
+}

backend/internal/domain/ingredient/handler.go

@@ -1,19 +1,25 @@
 package ingredient
 
 import (
+	"context"
 	"encoding/json"
 	"log/slog"
 	"net/http"
 	"strconv"
 )
 
+// IngredientSearcher is the data layer interface used by Handler.
+type IngredientSearcher interface {
+	Search(ctx context.Context, query string, limit int) ([]*IngredientMapping, error)
+}
+
 // Handler handles ingredient HTTP requests.
 type Handler struct {
-	repo *Repository
+	repo IngredientSearcher
 }
 
 // NewHandler creates a new Handler.
-func NewHandler(repo *Repository) *Handler {
+func NewHandler(repo IngredientSearcher) *Handler {
 	return &Handler{repo: repo}
 }
 

backend/internal/domain/menu/handler.go

@@ -84,7 +84,7 @@ func (h *Handler) GetMenu(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	weekStart, err := resolveWeekStart(r.URL.Query().Get("week"))
+	weekStart, err := ResolveWeekStart(r.URL.Query().Get("week"))
 	if err != nil {
 		writeError(w, http.StatusBadRequest, "invalid week parameter, expected YYYY-WNN")
 		return
@@ -120,7 +120,7 @@ func (h *Handler) GenerateMenu(w http.ResponseWriter, r *http.Request) {
 	}
 	_ = json.NewDecoder(r.Body).Decode(&body)
 
-	weekStart, err := resolveWeekStart(body.Week)
+	weekStart, err := ResolveWeekStart(body.Week)
 	if err != nil {
 		writeError(w, http.StatusBadRequest, "invalid week parameter")
 		return
@@ -302,7 +302,7 @@ func (h *Handler) GenerateShoppingList(w http.ResponseWriter, r *http.Request) {
 	}
 	_ = json.NewDecoder(r.Body).Decode(&body)
 
-	weekStart, err := resolveWeekStart(body.Week)
+	weekStart, err := ResolveWeekStart(body.Week)
 	if err != nil {
 		writeError(w, http.StatusBadRequest, "invalid week parameter")
 		return
@@ -342,7 +342,7 @@ func (h *Handler) GetShoppingList(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	weekStart, err := resolveWeekStart(r.URL.Query().Get("week"))
+	weekStart, err := ResolveWeekStart(r.URL.Query().Get("week"))
 	if err != nil {
 		writeError(w, http.StatusBadRequest, "invalid week parameter")
 		return
@@ -392,7 +392,7 @@ func (h *Handler) ToggleShoppingItem(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	weekStart, err := resolveWeekStart(r.URL.Query().Get("week"))
+	weekStart, err := ResolveWeekStart(r.URL.Query().Get("week"))
 	if err != nil {
 		writeError(w, http.StatusBadRequest, "invalid week parameter")
 		return
@@ -477,7 +477,7 @@ func recipeToCreateRequest(r ai.Recipe) dish.CreateRequest {
 	cr := dish.CreateRequest{
 		Name:        r.Title,
 		Description: r.Description,
-		CuisineSlug: mapCuisineSlug(r.Cuisine),
+		CuisineSlug: MapCuisineSlug(r.Cuisine),
 		ImageURL:    r.ImageURL,
 		Difficulty:  r.Difficulty,
 		PrepTimeMin: r.PrepTimeMin,
@@ -507,9 +507,9 @@ func recipeToCreateRequest(r ai.Recipe) dish.CreateRequest {
 	return cr
 }
 
-// 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",
@@ -538,8 +538,8 @@ func mapCuisineSlug(cuisine string) string {
 	return "other"
 }
 
-// resolveWeekStart parses "YYYY-WNN" or returns current week's Monday.
-func resolveWeekStart(week string) (string, error) {
+// ResolveWeekStart parses "YYYY-WNN" or returns current week's Monday.
+func ResolveWeekStart(week string) (string, error) {
 	if week == "" {
 		return currentWeekStart(), nil
 	}

backend/internal/domain/product/handler.go

@@ -1,6 +1,7 @@
 package product
 
 import (
+	"context"
 	"encoding/json"
 	"errors"
 	"log/slog"
@@ -10,13 +11,22 @@ import (
 	"github.com/go-chi/chi/v5"
 )
 
+// ProductRepository is the data layer interface used by Handler.
+type ProductRepository interface {
+	List(ctx context.Context, userID string) ([]*Product, error)
+	Create(ctx context.Context, userID string, req CreateRequest) (*Product, error)
+	BatchCreate(ctx context.Context, userID string, items []CreateRequest) ([]*Product, error)
+	Update(ctx context.Context, id, userID string, req UpdateRequest) (*Product, error)
+	Delete(ctx context.Context, id, userID string) error
+}
+
 // Handler handles /products HTTP requests.
 type Handler struct {
-	repo *Repository
+	repo ProductRepository
 }
 
 // NewHandler creates a new Handler.
-func NewHandler(repo *Repository) *Handler {
+func NewHandler(repo ProductRepository) *Handler {
 	return &Handler{repo: repo}
 }
 

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

@@ -0,0 +1,36 @@
+package mocks
+
+import (
+	"context"
+
+	"github.com/food-ai/backend/internal/domain/product"
+)
+
+// MockProductRepository is a test double implementing product.ProductRepository.
+type MockProductRepository struct {
+	ListFn        func(ctx context.Context, userID string) ([]*product.Product, error)
+	CreateFn      func(ctx context.Context, userID string, req product.CreateRequest) (*product.Product, error)
+	BatchCreateFn func(ctx context.Context, userID string, items []product.CreateRequest) ([]*product.Product, error)
+	UpdateFn      func(ctx context.Context, id, userID string, req product.UpdateRequest) (*product.Product, error)
+	DeleteFn      func(ctx context.Context, id, userID string) error
+}
+
+func (m *MockProductRepository) List(ctx context.Context, userID string) ([]*product.Product, error) {
+	return m.ListFn(ctx, userID)
+}
+
+func (m *MockProductRepository) Create(ctx context.Context, userID string, req product.CreateRequest) (*product.Product, error) {
+	return m.CreateFn(ctx, userID, req)
+}
+
+func (m *MockProductRepository) BatchCreate(ctx context.Context, userID string, items []product.CreateRequest) ([]*product.Product, error) {
+	return m.BatchCreateFn(ctx, userID, items)
+}
+
+func (m *MockProductRepository) Update(ctx context.Context, id, userID string, req product.UpdateRequest) (*product.Product, error) {
+	return m.UpdateFn(ctx, id, userID, req)
+}
+
+func (m *MockProductRepository) Delete(ctx context.Context, id, userID string) error {
+	return m.DeleteFn(ctx, id, userID)
+}

backend/internal/domain/recognition/handler.go

@@ -134,7 +134,7 @@ func (h *Handler) RecognizeProducts(w http.ResponseWriter, r *http.Request) {
 	}
 	wg.Wait()
 
-	merged := mergeAndDeduplicate(allItems)
+	merged := MergeAndDeduplicate(allItems)
 	enriched := h.enrichItems(r.Context(), merged)
 	writeJSON(w, http.StatusOK, map[string]any{"items": enriched})
 }
@@ -258,9 +258,9 @@ func (h *Handler) saveClassification(ctx context.Context, c *ai.IngredientClassi
 	return saved
 }
 
-// mergeAndDeduplicate combines results from multiple images.
+// MergeAndDeduplicate combines results from multiple images.
 // Items sharing the same name (case-insensitive) have their quantities summed.
-func mergeAndDeduplicate(batches [][]ai.RecognizedItem) []ai.RecognizedItem {
+func MergeAndDeduplicate(batches [][]ai.RecognizedItem) []ai.RecognizedItem {
 	seen := make(map[string]*ai.RecognizedItem)
 	var order []string
 

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",