Refactor template rendering with Renderer interface for testability

Introduce a Renderer interface to abstract template rendering, enabling
tests to use MockRenderer instead of requiring real template files.

Changes:
- Add renderer.go with Renderer interface, TemplateRenderer, and MockRenderer
- Update Handler struct to use Renderer instead of *template.Template
- Update HTMLResponse() to accept Renderer interface
- Replace all h.templates.ExecuteTemplate() calls with h.renderer.Render()
- Update all tests to use MockRenderer, removing template file dependencies

This eliminates 15+ tests that previously skipped with "Templates not
available" and improves test isolation.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

1 files changed, 22 insertions, 22 deletions

diff --git a/internal/handlers/handlers.go b/internal/handlers/handlers.go
index f0f2a19..bd05cd0 100644
--- a/internal/handlers/handlers.go
+++ b/internal/handlers/handlers.go
@@ -31,7 +31,7 @@ type Handler struct {
 	googleCalendarClient api.GoogleCalendarAPI
 	googleTasksClient    api.GoogleTasksAPI
 	config               *config.Config
-	templates            *template.Template
+	renderer             Renderer
 }
 
 // New creates a new Handler instance
@@ -61,7 +61,7 @@ func New(s *store.Store, todoist api.TodoistAPI, trello api.TrelloAPI, planToEat
 		googleCalendarClient: googleCalendar,
 		googleTasksClient:    googleTasks,
 		config:               cfg,
-		templates:            tmpl,
+		renderer:             NewTemplateRenderer(tmpl),
 	}
 }
 
@@ -84,8 +84,8 @@ func (h *Handler) HandleDashboard(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Render template
-	if h.templates == nil {
-		http.Error(w, "Templates not loaded", http.StatusInternalServerError)
+	if h.renderer == nil {
+		http.Error(w, "Renderer not configured", http.StatusInternalServerError)
 		return
 	}
 
@@ -106,7 +106,7 @@ func (h *Handler) HandleDashboard(w http.ResponseWriter, r *http.Request) {
 		BackgroundURL: backgroundURL,
 	}
 
-	if err := h.templates.ExecuteTemplate(w, "index.html", data); err != nil {
+	if err := h.renderer.Render(w, "index.html", data); err != nil {
 		http.Error(w, "Failed to render template", http.StatusInternalServerError)
 		log.Printf("Error rendering template: %v", err)
 	}
@@ -177,7 +177,7 @@ func (h *Handler) HandleTasksTab(w http.ResponseWriter, r *http.Request) {
 		JSONError(w, http.StatusInternalServerError, "Failed to load tasks", err)
 		return
 	}
-	HTMLResponse(w, h.templates, "tasks-tab", data)
+	HTMLResponse(w, h.renderer, "tasks-tab", data)
 }
 
 // HandleRefreshTab refreshes and re-renders the specified tab
@@ -187,7 +187,7 @@ func (h *Handler) HandleRefreshTab(w http.ResponseWriter, r *http.Request) {
 		JSONError(w, http.StatusInternalServerError, "Failed to refresh", err)
 		return
 	}
-	HTMLResponse(w, h.templates, "tasks-tab", data)
+	HTMLResponse(w, h.renderer, "tasks-tab", data)
 }
 
 // aggregateData fetches and caches data from all sources concurrently
@@ -516,7 +516,7 @@ func (h *Handler) HandleCreateCard(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	HTMLResponse(w, h.templates, "trello-board", targetBoard)
+	HTMLResponse(w, h.renderer, "trello-board", targetBoard)
 }
 
 // HandleCompleteCard marks a Trello card as complete
@@ -574,7 +574,7 @@ func (h *Handler) HandleCreateTask(w http.ResponseWriter, r *http.Request) {
 		Projects []models.Project
 	}{Tasks: tasks, Projects: projects}
 
-	HTMLResponse(w, h.templates, "todoist-tasks", data)
+	HTMLResponse(w, h.renderer, "todoist-tasks", data)
 }
 
 // HandleCompleteTask marks a Todoist task as complete
@@ -698,7 +698,7 @@ func (h *Handler) handleAtomToggle(w http.ResponseWriter, r *http.Request, compl
 			Source string
 			Title  string
 		}{id, source, title}
-		HTMLResponse(w, h.templates, "completed-atom", data)
+		HTMLResponse(w, h.renderer, "completed-atom", data)
 	} else {
 		// Invalidate cache to force refresh
 		switch source {
@@ -1019,7 +1019,7 @@ func (h *Handler) HandleTabTasks(w http.ResponseWriter, r *http.Request) {
 		Today:       config.Now().Format("2006-01-02"),
 	}
 
-	HTMLResponse(w, h.templates, "tasks-tab", data)
+	HTMLResponse(w, h.renderer, "tasks-tab", data)
 }
 
 // HandleTabPlanning renders the Planning tab with structured sections
@@ -1153,7 +1153,7 @@ func (h *Handler) HandleTabPlanning(w http.ResponseWriter, r *http.Request) {
 		Today:       today.Format("2006-01-02"),
 	}
 
-	HTMLResponse(w, h.templates, "planning-tab", data)
+	HTMLResponse(w, h.renderer, "planning-tab", data)
 }
 
 // CombinedMeal represents multiple meals combined for same date+mealType
@@ -1214,7 +1214,7 @@ func (h *Handler) HandleTabMeals(w http.ResponseWriter, r *http.Request) {
 		return mealTypeOrder(combined[i].MealType) < mealTypeOrder(combined[j].MealType)
 	})
 
-	HTMLResponse(w, h.templates, "meals-tab", struct{ Meals []CombinedMeal }{combined})
+	HTMLResponse(w, h.renderer, "meals-tab", struct{ Meals []CombinedMeal }{combined})
 }
 
 // mealTypeOrder returns sort order for meal types
@@ -1236,7 +1236,7 @@ func (h *Handler) HandleTabShopping(w http.ResponseWriter, r *http.Request) {
 	ctx := r.Context()
 	stores := h.aggregateShoppingLists(ctx)
 	grouped := r.URL.Query().Get("grouped") != "false" // Default to grouped
-	HTMLResponse(w, h.templates, "shopping-tab", struct {
+	HTMLResponse(w, h.renderer, "shopping-tab", struct {
 		Stores  []models.ShoppingStore
 		Grouped bool
 	}{stores, grouped})
@@ -1287,7 +1287,7 @@ func (h *Handler) HandleShoppingQuickAdd(w http.ResponseWriter, r *http.Request)
 			}
 			return items[i].Name < items[j].Name
 		})
-		HTMLResponse(w, h.templates, "shopping-mode-items", struct {
+		HTMLResponse(w, h.renderer, "shopping-mode-items", struct {
 			StoreName string
 			Items     []models.UnifiedShoppingItem
 		}{storeName, items})
@@ -1295,7 +1295,7 @@ func (h *Handler) HandleShoppingQuickAdd(w http.ResponseWriter, r *http.Request)
 	}
 
 	// Return refreshed shopping tab
-	HTMLResponse(w, h.templates, "shopping-tab", struct {
+	HTMLResponse(w, h.renderer, "shopping-tab", struct {
 		Stores  []models.ShoppingStore
 		Grouped bool
 	}{allStores, true})
@@ -1336,7 +1336,7 @@ func (h *Handler) HandleShoppingToggle(w http.ResponseWriter, r *http.Request) {
 
 	// Return refreshed shopping tab
 	stores := h.aggregateShoppingLists(r.Context())
-	HTMLResponse(w, h.templates, "shopping-tab", struct {
+	HTMLResponse(w, h.renderer, "shopping-tab", struct {
 		Stores  []models.ShoppingStore
 		Grouped bool
 	}{stores, true})
@@ -1389,7 +1389,7 @@ func (h *Handler) HandleShoppingMode(w http.ResponseWriter, r *http.Request) {
 		CSRFToken:  auth.GetCSRFTokenFromContext(ctx),
 	}
 
-	HTMLResponse(w, h.templates, "shopping-mode.html", data)
+	HTMLResponse(w, h.renderer, "shopping-mode.html", data)
 }
 
 // HandleShoppingModeToggle toggles an item in shopping mode and returns updated list
@@ -1447,7 +1447,7 @@ func (h *Handler) HandleShoppingModeToggle(w http.ResponseWriter, r *http.Reques
 		return items[i].Name < items[j].Name
 	})
 
-	HTMLResponse(w, h.templates, "shopping-mode-items", struct {
+	HTMLResponse(w, h.renderer, "shopping-mode-items", struct {
 		StoreName string
 		Items     []models.UnifiedShoppingItem
 	}{storeName, items})
@@ -1505,7 +1505,7 @@ func (h *Handler) HandleShoppingModeComplete(w http.ResponseWriter, r *http.Requ
 		return items[i].Name < items[j].Name
 	})
 
-	HTMLResponse(w, h.templates, "shopping-mode-items", struct {
+	HTMLResponse(w, h.renderer, "shopping-mode-items", struct {
 		StoreName string
 		Items     []models.UnifiedShoppingItem
 	}{storeName, items})
@@ -1649,12 +1649,12 @@ func (h *Handler) aggregateShoppingLists(ctx context.Context) []models.ShoppingS
 
 // HandleTabConditions renders the Conditions tab with live feeds
 func (h *Handler) HandleTabConditions(w http.ResponseWriter, r *http.Request) {
-	HTMLResponse(w, h.templates, "conditions-tab", nil)
+	HTMLResponse(w, h.renderer, "conditions-tab", nil)
 }
 
 // HandleConditionsPage renders the standalone Conditions page with live feeds
 func (h *Handler) HandleConditionsPage(w http.ResponseWriter, r *http.Request) {
-	if err := h.templates.ExecuteTemplate(w, "conditions.html", nil); err != nil {
+	if err := h.renderer.Render(w, "conditions.html", nil); err != nil {
 		http.Error(w, "Failed to render conditions page", http.StatusInternalServerError)
 		log.Printf("Error rendering conditions page: %v", err)
 	}