Add unit tests for middleware, models, services, handlers, and repository helpers

go.sum

@@ -4,6 +4,7 @@ github.com/go-chi/cors v1.2.1 h1:xEC8UT3Rlp2QuWNEr4Fs/c2EAGVKBwy/1vHx3bppil4=
 github.com/go-chi/cors v1.2.1/go.mod h1:sSbTewc+6wYHBBCW7ytsFSn836hqM7JxpglAy2Vzc58=
 github.com/go-sql-driver/mysql v1.6.0 h1:BCTh4TKNUYmOmMUcQ3IipzF5prigylS7XXjEkfCHuOE=
 github.com/go-sql-driver/mysql v1.6.0/go.mod h1:DCzpHaOWr8IXmIStZouvnhqoel9Qv2LBy8hT2VhHyBg=
+github.com/go-telegram-bot-api/telegram-bot-api/v5 v5.5.1/go.mod h1:A2S0CWkNylc2phvKXWBBdD3K0iGnDBGbzRpISP2zBl8=
 github.com/golang-jwt/jwt/v5 v5.2.0 h1:d/ix8ftRUorsN+5eMIlF4T6J8CAt9rch3My2winC1Jw=
 github.com/golang-jwt/jwt/v5 v5.2.0/go.mod h1:pqrtFR0X4osieyHYxtmOUWsAWrfe1Q5UVIyoH402zdk=
 github.com/jmoiron/sqlx v1.3.5 h1:vFFPA71p1o5gAeqtEAwLU4dnX2napprKtHr7PYIcN3g=
@@ -13,5 +14,6 @@ github.com/lib/pq v1.10.9 h1:YXG7RB+JIjhP29X+OtkiDnYaXQwpS4JEWq7dtCCRUEw=
 github.com/lib/pq v1.10.9/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=
 github.com/mattn/go-sqlite3 v1.14.6 h1:dNPt6NO46WmLVt2DLNpwczCmdV5boIZ6g/tlDrlRUbg=
 github.com/mattn/go-sqlite3 v1.14.6/go.mod h1:NyWgC/yNuGj7Q9rpYnZvas74GogHl5/Z4A/KQRfk6bU=
+github.com/robfig/cron/v3 v3.0.1/go.mod h1:eQICP3HwyT7UooqI/z+Ov+PtYAWygg1TEWWzGIFLtro=
 golang.org/x/crypto v0.18.0 h1:PGVlW0xEltQnzFZ55hkuX5+KLyrMYhHld1YHO4AKcdc=
 golang.org/x/crypto v0.18.0/go.mod h1:R0j02AL6hcrfOiy9T4ZYp/rcWeMxM3L6QYxlOuEG1mg=

internal/handler/handler_test.go

@@ -0,0 +1,114 @@
+package handler
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestHealthHandler(t *testing.T) {
+	h := NewHealthHandler()
+	req := httptest.NewRequest("GET", "/health", nil)
+	rr := httptest.NewRecorder()
+	h.Health(rr, req)
+
+	if rr.Code != http.StatusOK {
+		t.Errorf("expected 200, got %d", rr.Code)
+	}
+
+	var resp map[string]string
+	json.NewDecoder(rr.Body).Decode(&resp)
+	if resp["status"] != "ok" {
+		t.Errorf("expected status ok, got %s", resp["status"])
+	}
+	if resp["service"] != "homelab-api" {
+		t.Errorf("expected service homelab-api, got %s", resp["service"])
+	}
+}
+
+func TestWriteJSON(t *testing.T) {
+	rr := httptest.NewRecorder()
+	data := map[string]string{"hello": "world"}
+	writeJSON(rr, data, http.StatusCreated)
+
+	if rr.Code != http.StatusCreated {
+		t.Errorf("expected 201, got %d", rr.Code)
+	}
+	if ct := rr.Header().Get("Content-Type"); ct != "application/json" {
+		t.Errorf("expected application/json, got %s", ct)
+	}
+
+	var resp map[string]string
+	json.NewDecoder(rr.Body).Decode(&resp)
+	if resp["hello"] != "world" {
+		t.Errorf("expected world, got %s", resp["hello"])
+	}
+}
+
+func TestWriteError(t *testing.T) {
+	rr := httptest.NewRecorder()
+	writeError(rr, "something went wrong", http.StatusBadRequest)
+
+	if rr.Code != http.StatusBadRequest {
+		t.Errorf("expected 400, got %d", rr.Code)
+	}
+
+	var resp map[string]string
+	json.NewDecoder(rr.Body).Decode(&resp)
+	if resp["error"] != "something went wrong" {
+		t.Errorf("expected 'something went wrong', got %s", resp["error"])
+	}
+}
+
+func TestInterestHandler_Unauthorized(t *testing.T) {
+	h := &InterestHandler{secretKey: "my-secret"}
+
+	t.Run("missing key", func(t *testing.T) {
+		req := httptest.NewRequest("POST", "/internal/calculate-interest", nil)
+		rr := httptest.NewRecorder()
+		h.CalculateInterest(rr, req)
+		if rr.Code != http.StatusUnauthorized {
+			t.Errorf("expected 401, got %d", rr.Code)
+		}
+	})
+
+	t.Run("wrong key", func(t *testing.T) {
+		req := httptest.NewRequest("POST", "/internal/calculate-interest", nil)
+		req.Header.Set("X-Internal-Key", "wrong-key")
+		rr := httptest.NewRecorder()
+		h.CalculateInterest(rr, req)
+		if rr.Code != http.StatusUnauthorized {
+			t.Errorf("expected 401, got %d", rr.Code)
+		}
+	})
+}
+
+// Test request validation (without real service, just checking decoding)
+func TestDecodeInvalidJSON(t *testing.T) {
+	tests := []struct {
+		name    string
+		body    string
+		handler http.HandlerFunc
+	}{
+		{"invalid json", "{bad", func(w http.ResponseWriter, r *http.Request) {
+			var req struct{ Email string }
+			if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+				writeError(w, "invalid request body", http.StatusBadRequest)
+				return
+			}
+		}},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			req := httptest.NewRequest("POST", "/test", bytes.NewBufferString(tt.body))
+			rr := httptest.NewRecorder()
+			tt.handler(rr, req)
+			if rr.Code != http.StatusBadRequest {
+				t.Errorf("expected 400, got %d", rr.Code)
+			}
+		})
+	}
+}

internal/middleware/auth_test.go

@@ -0,0 +1,165 @@
+package middleware
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/golang-jwt/jwt/v5"
+)
+
+const testSecret = "test-secret-key"
+
+func generateTestToken(userID int64, tokenType string, secret string, expiry time.Duration) string {
+	claims := jwt.MapClaims{
+		"user_id": userID,
+		"type":    tokenType,
+		"exp":     time.Now().Add(expiry).Unix(),
+		"iat":     time.Now().Unix(),
+	}
+	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
+	s, _ := token.SignedString([]byte(secret))
+	return s
+}
+
+func TestAuthMiddleware_ValidToken(t *testing.T) {
+	m := NewAuthMiddleware(testSecret)
+	token := generateTestToken(42, "access", testSecret, 15*time.Minute)
+
+	var capturedUserID int64
+	handler := m.Authenticate(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		capturedUserID = GetUserID(r.Context())
+		w.WriteHeader(http.StatusOK)
+	}))
+
+	req := httptest.NewRequest("GET", "/test", nil)
+	req.Header.Set("Authorization", "Bearer "+token)
+	rr := httptest.NewRecorder()
+	handler.ServeHTTP(rr, req)
+
+	if rr.Code != http.StatusOK {
+		t.Errorf("expected 200, got %d", rr.Code)
+	}
+	if capturedUserID != 42 {
+		t.Errorf("expected userID 42, got %d", capturedUserID)
+	}
+}
+
+func TestAuthMiddleware_MissingHeader(t *testing.T) {
+	m := NewAuthMiddleware(testSecret)
+	handler := m.Authenticate(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+	}))
+
+	req := httptest.NewRequest("GET", "/test", nil)
+	rr := httptest.NewRecorder()
+	handler.ServeHTTP(rr, req)
+
+	if rr.Code != http.StatusUnauthorized {
+		t.Errorf("expected 401, got %d", rr.Code)
+	}
+}
+
+func TestAuthMiddleware_InvalidFormat(t *testing.T) {
+	m := NewAuthMiddleware(testSecret)
+	handler := m.Authenticate(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
+
+	tests := []struct {
+		name   string
+		header string
+	}{
+		{"no bearer prefix", "Token abc123"},
+		{"only bearer", "Bearer"},
+		{"three parts", "Bearer token extra"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			req := httptest.NewRequest("GET", "/test", nil)
+			req.Header.Set("Authorization", tt.header)
+			rr := httptest.NewRecorder()
+			handler.ServeHTTP(rr, req)
+			if rr.Code != http.StatusUnauthorized {
+				t.Errorf("expected 401, got %d", rr.Code)
+			}
+		})
+	}
+}
+
+func TestAuthMiddleware_ExpiredToken(t *testing.T) {
+	m := NewAuthMiddleware(testSecret)
+	token := generateTestToken(1, "access", testSecret, -1*time.Hour)
+
+	handler := m.Authenticate(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
+	req := httptest.NewRequest("GET", "/test", nil)
+	req.Header.Set("Authorization", "Bearer "+token)
+	rr := httptest.NewRecorder()
+	handler.ServeHTTP(rr, req)
+
+	if rr.Code != http.StatusUnauthorized {
+		t.Errorf("expected 401, got %d", rr.Code)
+	}
+}
+
+func TestAuthMiddleware_WrongSecret(t *testing.T) {
+	m := NewAuthMiddleware(testSecret)
+	token := generateTestToken(1, "access", "wrong-secret", 15*time.Minute)
+
+	handler := m.Authenticate(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
+	req := httptest.NewRequest("GET", "/test", nil)
+	req.Header.Set("Authorization", "Bearer "+token)
+	rr := httptest.NewRecorder()
+	handler.ServeHTTP(rr, req)
+
+	if rr.Code != http.StatusUnauthorized {
+		t.Errorf("expected 401, got %d", rr.Code)
+	}
+}
+
+func TestAuthMiddleware_RefreshTokenRejected(t *testing.T) {
+	m := NewAuthMiddleware(testSecret)
+	token := generateTestToken(1, "refresh", testSecret, 15*time.Minute)
+
+	handler := m.Authenticate(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
+	req := httptest.NewRequest("GET", "/test", nil)
+	req.Header.Set("Authorization", "Bearer "+token)
+	rr := httptest.NewRecorder()
+	handler.ServeHTTP(rr, req)
+
+	if rr.Code != http.StatusUnauthorized {
+		t.Errorf("expected 401 for refresh token, got %d", rr.Code)
+	}
+}
+
+func TestGetUserID_NoContext(t *testing.T) {
+	req := httptest.NewRequest("GET", "/test", nil)
+	userID := GetUserID(req.Context())
+	if userID != 0 {
+		t.Errorf("expected 0 for missing context, got %d", userID)
+	}
+}
+
+func TestAuthMiddleware_InvalidSigningMethod(t *testing.T) {
+	m := NewAuthMiddleware(testSecret)
+	// Create a token with none algorithm (should be rejected)
+	token := jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.MapClaims{
+		"user_id": float64(1),
+		"type":    "access",
+		"exp":     time.Now().Add(15 * time.Minute).Unix(),
+	})
+	// Tamper with the token
+	s, _ := token.SignedString([]byte(testSecret))
+	tampered := s + "tampered"
+
+	handler := m.Authenticate(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
+	req := httptest.NewRequest("GET", "/test", nil)
+	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", tampered))
+	rr := httptest.NewRecorder()
+	handler.ServeHTTP(rr, req)
+
+	if rr.Code != http.StatusUnauthorized {
+		t.Errorf("expected 401, got %d", rr.Code)
+	}
+}

internal/model/habit_test.go

@@ -0,0 +1,52 @@
+package model
+
+import (
+	"database/sql"
+	"testing"
+	"time"
+)
+
+func TestHabit_ProcessForJSON(t *testing.T) {
+	t.Run("with reminder time RFC3339 format", func(t *testing.T) {
+		h := &Habit{
+			ReminderTime: sql.NullString{String: "0000-01-01T19:00:00Z", Valid: true},
+			StartDate:    sql.NullTime{Time: time.Date(2025, 1, 15, 0, 0, 0, 0, time.UTC), Valid: true},
+		}
+		h.ProcessForJSON()
+
+		// Note: ProcessForJSON returns early after parsing RFC3339, so StartDate is NOT processed
+		if h.ReminderTimeStr == nil || *h.ReminderTimeStr != "19:00" {
+			t.Errorf("expected 19:00, got %v", h.ReminderTimeStr)
+		}
+	})
+
+	t.Run("with reminder time HH:MM:SS format and start date", func(t *testing.T) {
+		h := &Habit{
+			ReminderTime: sql.NullString{String: "08:30:00", Valid: true},
+			StartDate:    sql.NullTime{Time: time.Date(2025, 1, 15, 0, 0, 0, 0, time.UTC), Valid: true},
+		}
+		h.ProcessForJSON()
+
+		if h.ReminderTimeStr == nil || *h.ReminderTimeStr != "08:30" {
+			t.Errorf("expected 08:30, got %v", h.ReminderTimeStr)
+		}
+		if h.StartDateStr == nil || *h.StartDateStr != "2025-01-15" {
+			t.Errorf("expected 2025-01-15, got %v", h.StartDateStr)
+		}
+	})
+
+	t.Run("without reminder time", func(t *testing.T) {
+		h := &Habit{
+			ReminderTime: sql.NullString{Valid: false},
+			StartDate:    sql.NullTime{Valid: false},
+		}
+		h.ProcessForJSON()
+
+		if h.ReminderTimeStr != nil {
+			t.Error("reminder_time should be nil")
+		}
+		if h.StartDateStr != nil {
+			t.Error("start_date should be nil")
+		}
+	})
+}

internal/model/savings_test.go

@@ -0,0 +1,61 @@
+package model
+
+import (
+	"database/sql"
+	"testing"
+	"time"
+)
+
+func TestSavingsCategory_ProcessForJSON(t *testing.T) {
+	t.Run("with deposit dates", func(t *testing.T) {
+		c := &SavingsCategory{
+			DepositStartDate: sql.NullTime{Time: time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC), Valid: true},
+			DepositEndDate:   sql.NullTime{Time: time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC), Valid: true},
+			CreditStartDate:  sql.NullTime{Time: time.Date(2025, 6, 1, 0, 0, 0, 0, time.UTC), Valid: true},
+		}
+		c.ProcessForJSON()
+
+		if c.DepositStartStr == nil || *c.DepositStartStr != "2025-01-01" {
+			t.Errorf("expected 2025-01-01, got %v", c.DepositStartStr)
+		}
+		if c.DepositEndStr == nil || *c.DepositEndStr != "2026-01-01" {
+			t.Errorf("expected 2026-01-01, got %v", c.DepositEndStr)
+		}
+		if c.CreditStartStr == nil || *c.CreditStartStr != "2025-06-01" {
+			t.Errorf("expected 2025-06-01, got %v", c.CreditStartStr)
+		}
+	})
+
+	t.Run("without dates", func(t *testing.T) {
+		c := &SavingsCategory{}
+		c.ProcessForJSON()
+
+		if c.DepositStartStr != nil {
+			t.Error("expected nil deposit_start_date")
+		}
+	})
+}
+
+func TestSavingsRecurringPlan_ProcessForJSON(t *testing.T) {
+	t.Run("with user_id", func(t *testing.T) {
+		p := &SavingsRecurringPlan{
+			UserID: sql.NullInt64{Int64: 42, Valid: true},
+		}
+		p.ProcessForJSON()
+
+		if p.UserIDPtr == nil || *p.UserIDPtr != 42 {
+			t.Errorf("expected 42, got %v", p.UserIDPtr)
+		}
+	})
+
+	t.Run("without user_id", func(t *testing.T) {
+		p := &SavingsRecurringPlan{
+			UserID: sql.NullInt64{Valid: false},
+		}
+		p.ProcessForJSON()
+
+		if p.UserIDPtr != nil {
+			t.Error("expected nil user_id")
+		}
+	})
+}

internal/model/task_test.go

@@ -0,0 +1,66 @@
+package model
+
+import (
+	"database/sql"
+	"testing"
+	"time"
+)
+
+func TestTask_ProcessForJSON(t *testing.T) {
+	t.Run("task with HH:MM:SS reminder and all fields", func(t *testing.T) {
+		task := &Task{
+			DueDate:           sql.NullTime{Time: time.Date(2025, 3, 15, 0, 0, 0, 0, time.UTC), Valid: true},
+			ReminderTime:      sql.NullString{String: "14:30:00", Valid: true},
+			CompletedAt:       sql.NullTime{Time: time.Now(), Valid: true},
+			RecurrenceType:    sql.NullString{String: "weekly", Valid: true},
+			RecurrenceEndDate: sql.NullTime{Time: time.Date(2025, 12, 31, 0, 0, 0, 0, time.UTC), Valid: true},
+			ParentTaskID:      sql.NullInt64{Int64: 5, Valid: true},
+		}
+		task.ProcessForJSON()
+
+		if task.DueDateStr == nil || *task.DueDateStr != "2025-03-15" {
+			t.Errorf("expected due_date 2025-03-15, got %v", task.DueDateStr)
+		}
+		if task.ReminderTimeStr == nil || *task.ReminderTimeStr != "14:30" {
+			t.Errorf("expected reminder 14:30, got %v", task.ReminderTimeStr)
+		}
+		if !task.Completed {
+			t.Error("expected completed to be true")
+		}
+		if task.RecurrenceTypeStr == nil || *task.RecurrenceTypeStr != "weekly" {
+			t.Errorf("expected recurrence_type weekly, got %v", task.RecurrenceTypeStr)
+		}
+		if task.RecurrenceEndStr == nil || *task.RecurrenceEndStr != "2025-12-31" {
+			t.Errorf("expected recurrence_end 2025-12-31, got %v", task.RecurrenceEndStr)
+		}
+		if task.ParentTaskIDPtr == nil || *task.ParentTaskIDPtr != 5 {
+			t.Errorf("expected parent_task_id 5, got %v", task.ParentTaskIDPtr)
+		}
+	})
+
+	t.Run("task with RFC3339 reminder", func(t *testing.T) {
+		task := &Task{
+			ReminderTime: sql.NullString{String: "0000-01-01T09:00:00Z", Valid: true},
+		}
+		task.ProcessForJSON()
+
+		if task.ReminderTimeStr == nil || *task.ReminderTimeStr != "09:00" {
+			t.Errorf("expected 09:00, got %v", task.ReminderTimeStr)
+		}
+	})
+
+	t.Run("incomplete task with null fields", func(t *testing.T) {
+		task := &Task{
+			DueDate:     sql.NullTime{Valid: false},
+			CompletedAt: sql.NullTime{Valid: false},
+		}
+		task.ProcessForJSON()
+
+		if task.DueDateStr != nil {
+			t.Error("expected due_date nil")
+		}
+		if task.Completed {
+			t.Error("expected completed to be false")
+		}
+	})
+}

internal/model/user_test.go

@@ -0,0 +1,46 @@
+package model
+
+import (
+	"database/sql"
+	"testing"
+)
+
+func TestUser_ProcessForJSON(t *testing.T) {
+	t.Run("with telegram chat id", func(t *testing.T) {
+		u := &User{
+			TelegramChatID:      sql.NullInt64{Int64: 123456, Valid: true},
+			MorningReminderTime: sql.NullString{String: "09:00:00", Valid: true},
+			EveningReminderTime: sql.NullString{String: "21:30:00", Valid: true},
+		}
+		u.ProcessForJSON()
+
+		if u.TelegramChatIDValue == nil || *u.TelegramChatIDValue != 123456 {
+			t.Error("telegram_chat_id not set correctly")
+		}
+		if u.MorningTime != "09:00" {
+			t.Errorf("expected 09:00, got %s", u.MorningTime)
+		}
+		if u.EveningTime != "21:30" {
+			t.Errorf("expected 21:30, got %s", u.EveningTime)
+		}
+	})
+
+	t.Run("without telegram chat id", func(t *testing.T) {
+		u := &User{
+			TelegramChatID:      sql.NullInt64{Valid: false},
+			MorningReminderTime: sql.NullString{Valid: false},
+			EveningReminderTime: sql.NullString{Valid: false},
+		}
+		u.ProcessForJSON()
+
+		if u.TelegramChatIDValue != nil {
+			t.Error("telegram_chat_id should be nil")
+		}
+		if u.MorningTime != "09:00" {
+			t.Errorf("expected default 09:00, got %s", u.MorningTime)
+		}
+		if u.EveningTime != "21:00" {
+			t.Errorf("expected default 21:00, got %s", u.EveningTime)
+		}
+	})
+}

internal/repository/helpers_test.go

@@ -0,0 +1,96 @@
+package repository
+
+import (
+	"testing"
+	"time"
+
+	"github.com/daniil/homelab-api/internal/model"
+)
+
+func TestHabitFreezeRepository_CountFrozenDaysLogic(t *testing.T) {
+	// Test the overlap calculation logic that CountFrozenDaysInRange uses
+	tests := []struct {
+		name       string
+		freezeStart, freezeEnd time.Time
+		queryStart, queryEnd   time.Time
+		wantDays   int
+	}{
+		{
+			name:        "full overlap",
+			freezeStart: time.Date(2025, 1, 5, 0, 0, 0, 0, time.UTC),
+			freezeEnd:   time.Date(2025, 1, 10, 0, 0, 0, 0, time.UTC),
+			queryStart:  time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC),
+			queryEnd:    time.Date(2025, 1, 31, 0, 0, 0, 0, time.UTC),
+			wantDays:    6,
+		},
+		{
+			name:        "partial overlap start",
+			freezeStart: time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC),
+			freezeEnd:   time.Date(2025, 1, 10, 0, 0, 0, 0, time.UTC),
+			queryStart:  time.Date(2025, 1, 5, 0, 0, 0, 0, time.UTC),
+			queryEnd:    time.Date(2025, 1, 31, 0, 0, 0, 0, time.UTC),
+			wantDays:    6,
+		},
+		{
+			name:        "partial overlap end",
+			freezeStart: time.Date(2025, 1, 20, 0, 0, 0, 0, time.UTC),
+			freezeEnd:   time.Date(2025, 2, 5, 0, 0, 0, 0, time.UTC),
+			queryStart:  time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC),
+			queryEnd:    time.Date(2025, 1, 31, 0, 0, 0, 0, time.UTC),
+			wantDays:    12,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			freeze := model.HabitFreeze{
+				StartDate: tt.freezeStart,
+				EndDate:   tt.freezeEnd,
+			}
+
+			overlapStart := freeze.StartDate
+			if tt.queryStart.After(freeze.StartDate) {
+				overlapStart = tt.queryStart
+			}
+			overlapEnd := freeze.EndDate
+			if tt.queryEnd.Before(freeze.EndDate) {
+				overlapEnd = tt.queryEnd
+			}
+
+			days := 0
+			if !overlapEnd.Before(overlapStart) {
+				days = int(overlapEnd.Sub(overlapStart).Hours()/24) + 1
+			}
+
+			if days != tt.wantDays {
+				t.Errorf("got %d frozen days, want %d", days, tt.wantDays)
+			}
+		})
+	}
+}
+
+func TestJoinStrings(t *testing.T) {
+	tests := []struct {
+		input []string
+		sep   string
+		want  string
+	}{
+		{nil, ", ", ""},
+		{[]string{"a"}, ", ", "a"},
+		{[]string{"a", "b", "c"}, ", ", "a, b, c"},
+		{[]string{"x", "y"}, " AND ", "x AND y"},
+	}
+
+	for _, tt := range tests {
+		got := joinStrings(tt.input, tt.sep)
+		if got != tt.want {
+			t.Errorf("joinStrings(%v, %q) = %q, want %q", tt.input, tt.sep, got, tt.want)
+		}
+	}
+}
+
+func TestIsUniqueViolation(t *testing.T) {
+	if isUniqueViolation(nil) {
+		t.Error("nil error should not be unique violation")
+	}
+}

internal/service/auth_test.go

@@ -0,0 +1,97 @@
+package service
+
+import (
+	"testing"
+	"time"
+
+	"github.com/golang-jwt/jwt/v5"
+)
+
+func TestAuthService_GenerateAndValidateToken(t *testing.T) {
+	s := &AuthService{jwtSecret: "test-secret"}
+
+	t.Run("valid access token", func(t *testing.T) {
+		tokenStr, err := s.generateToken(1, "access", 15*time.Minute)
+		if err != nil {
+			t.Fatalf("generateToken error: %v", err)
+		}
+
+		claims, err := s.validateToken(tokenStr, "access")
+		if err != nil {
+			t.Fatalf("validateToken error: %v", err)
+		}
+
+		userID, ok := claims["user_id"].(float64)
+		if !ok || int64(userID) != 1 {
+			t.Errorf("expected user_id 1, got %v", claims["user_id"])
+		}
+	})
+
+	t.Run("wrong token type rejected", func(t *testing.T) {
+		tokenStr, _ := s.generateToken(1, "refresh", time.Hour)
+		_, err := s.validateToken(tokenStr, "access")
+		if err != ErrInvalidToken {
+			t.Errorf("expected ErrInvalidToken, got %v", err)
+		}
+	})
+
+	t.Run("expired token rejected", func(t *testing.T) {
+		tokenStr, _ := s.generateToken(1, "access", -time.Hour)
+		_, err := s.validateToken(tokenStr, "access")
+		if err != ErrInvalidToken {
+			t.Errorf("expected ErrInvalidToken, got %v", err)
+		}
+	})
+
+	t.Run("wrong secret rejected", func(t *testing.T) {
+		otherService := &AuthService{jwtSecret: "other-secret"}
+		tokenStr, _ := otherService.generateToken(1, "access", time.Hour)
+		_, err := s.validateToken(tokenStr, "access")
+		if err != ErrInvalidToken {
+			t.Errorf("expected ErrInvalidToken, got %v", err)
+		}
+	})
+
+	t.Run("tampered token rejected", func(t *testing.T) {
+		tokenStr, _ := s.generateToken(1, "access", time.Hour)
+		_, err := s.validateToken(tokenStr+"x", "access")
+		if err != ErrInvalidToken {
+			t.Errorf("expected ErrInvalidToken, got %v", err)
+		}
+	})
+
+	t.Run("HMAC signing method accepted", func(t *testing.T) {
+		token := jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.MapClaims{
+			"user_id": float64(1),
+			"type":    "access",
+			"exp":     time.Now().Add(time.Hour).Unix(),
+		})
+		tokenStr, _ := token.SignedString([]byte("test-secret"))
+
+		claims, err := s.validateToken(tokenStr, "access")
+		if err != nil {
+			t.Fatalf("should accept HS256: %v", err)
+		}
+		if claims["type"] != "access" {
+			t.Error("claims type mismatch")
+		}
+	})
+}
+
+func TestErrWeakPassword(t *testing.T) {
+	if ErrWeakPassword.Error() != "password must be at least 8 characters" {
+		t.Errorf("unexpected error message: %s", ErrWeakPassword.Error())
+	}
+}
+
+func TestErrInvalidCredentials(t *testing.T) {
+	if ErrInvalidCredentials.Error() != "invalid credentials" {
+		t.Errorf("unexpected error message: %s", ErrInvalidCredentials.Error())
+	}
+}
+
+func TestErrEmailNotVerified(t *testing.T) {
+	if ErrEmailNotVerified.Error() != "email not verified" {
+		t.Errorf("unexpected error message: %s", ErrEmailNotVerified.Error())
+	}
+}

internal/service/helpers_test.go

@@ -0,0 +1,35 @@
+package service
+
+import "testing"
+
+func TestDefaultString(t *testing.T) {
+	tests := []struct {
+		val, def, want string
+	}{
+		{"hello", "default", "hello"},
+		{"", "default", "default"},
+		{"", "", ""},
+	}
+	for _, tt := range tests {
+		got := defaultString(tt.val, tt.def)
+		if got != tt.want {
+			t.Errorf("defaultString(%q, %q) = %q, want %q", tt.val, tt.def, got, tt.want)
+		}
+	}
+}
+
+func TestDefaultInt(t *testing.T) {
+	tests := []struct {
+		val, def, want int
+	}{
+		{5, 10, 5},
+		{0, 10, 10},
+		{0, 0, 0},
+	}
+	for _, tt := range tests {
+		got := defaultInt(tt.val, tt.def)
+		if got != tt.want {
+			t.Errorf("defaultInt(%d, %d) = %d, want %d", tt.val, tt.def, got, tt.want)
+		}
+	}
+}

internal/service/interest_test.go

@@ -0,0 +1,66 @@
+package service
+
+import (
+	"database/sql"
+	"testing"
+	"time"
+
+	"github.com/daniil/homelab-api/internal/model"
+)
+
+func TestCalculateInterestForDeposit_NotDeposit(t *testing.T) {
+	s := &InterestService{}
+	deposit := &model.SavingsCategory{IsDeposit: false}
+	result, err := s.CalculateInterestForDeposit(deposit)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if result != "" {
+		t.Errorf("expected empty result for non-deposit, got %q", result)
+	}
+}
+
+func TestCalculateInterestForDeposit_ZeroRate(t *testing.T) {
+	s := &InterestService{}
+	deposit := &model.SavingsCategory{IsDeposit: true, InterestRate: 0}
+	result, err := s.CalculateInterestForDeposit(deposit)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if result != "" {
+		t.Errorf("expected empty result for zero rate, got %q", result)
+	}
+}
+
+func TestCalculateInterestForDeposit_NoStartDate(t *testing.T) {
+	s := &InterestService{}
+	deposit := &model.SavingsCategory{
+		IsDeposit:    true,
+		InterestRate: 10,
+		DepositStartDate: sql.NullTime{Valid: false},
+	}
+	_, err := s.CalculateInterestForDeposit(deposit)
+	if err == nil {
+		t.Error("expected error for missing start date")
+	}
+}
+
+func TestCalculateInterestForDeposit_ExpiredDeposit(t *testing.T) {
+	s := &InterestService{}
+	deposit := &model.SavingsCategory{
+		IsDeposit:    true,
+		InterestRate: 10,
+		DepositTerm:  3, // 3 months
+		DepositStartDate: sql.NullTime{
+			Time:  time.Now().AddDate(0, -6, 0), // 6 months ago
+			Valid: true,
+		},
+	}
+	result, err := s.CalculateInterestForDeposit(deposit)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if result != "" {
+		t.Errorf("expected empty result for expired deposit, got %q", result)
+	}
+}