feat: 系统性改进后端测试体系

- 新增 6 个测试场景 (config load pipe, handler errors, service aggregation, engine degradation, openai decoder edges, negative tests)
- 更新测试工具规格 (mockgen, in-memory SQLite)
- 覆盖率目标从 >80% 提升至 >85%
- 新增 test-unit 和 test-integration Makefile 命令
- 新增死代码清理和 mockgen 需求
- 归档变更至 openspec/changes/archive/2026-04-22-improve-backend-testing/

backend/internal/service/model_service.go

@@ -2,6 +2,8 @@ package service
 
 import "nex/backend/internal/domain"
 
+//go:generate go run go.uber.org/mock/mockgen -source=model_service.go -destination=../../tests/mocks/mock_model_service.go -package=mocks
+
 // ModelService 模型服务接口
 type ModelService interface {
 	Create(model *domain.Model) error

backend/internal/service/provider_service.go

@@ -2,6 +2,8 @@ package service
 
 import "nex/backend/internal/domain"
 
+//go:generate go run go.uber.org/mock/mockgen -source=provider_service.go -destination=../../tests/mocks/mock_provider_service.go -package=mocks
+
 // ProviderService 供应商服务接口
 type ProviderService interface {
 	Create(provider *domain.Provider) error

backend/internal/service/routing_service.go

@@ -2,6 +2,8 @@ package service
 
 import "nex/backend/internal/domain"
 
+//go:generate go run go.uber.org/mock/mockgen -source=routing_service.go -destination=../../tests/mocks/mock_routing_service.go -package=mocks
+
 // RoutingService 路由服务接口
 type RoutingService interface {
 	RouteByModelName(providerID, modelName string) (*domain.RouteResult, error)

backend/internal/service/service_supplemental_test.go

@@ -16,7 +16,7 @@ func TestProviderService_Update(t *testing.T) {
 	modelRepo := repository.NewModelRepository(db)
 	svc := NewProviderService(repo, modelRepo)
 
-	svc.Create(&domain.Provider{ID: "p1", Name: "Original", APIKey: "key", BaseURL: "https://test.com"})
+	require.NoError(t, svc.Create(&domain.Provider{ID: "p1", Name: "Original", APIKey: "key", BaseURL: "https://test.com"}))
 
 	err := svc.Update("p1", map[string]interface{}{"name": "Updated"})
 	require.NoError(t, err)
@@ -42,7 +42,7 @@ func TestModelService_Get(t *testing.T) {
 	modelRepo := repository.NewModelRepository(db)
 	svc := NewModelService(modelRepo, providerRepo)
 
-	providerRepo.Create(&domain.Provider{ID: "p1", Name: "P1", APIKey: "key", BaseURL: "https://test.com"})
+	require.NoError(t, providerRepo.Create(&domain.Provider{ID: "p1", Name: "P1", APIKey: "key", BaseURL: "https://test.com"}))
 	model := &domain.Model{ProviderID: "p1", ModelName: "gpt-4"}
 	require.NoError(t, svc.Create(model))
 
@@ -57,7 +57,7 @@ func TestModelService_Update(t *testing.T) {
 	modelRepo := repository.NewModelRepository(db)
 	svc := NewModelService(modelRepo, providerRepo)
 
-	providerRepo.Create(&domain.Provider{ID: "p1", Name: "P1", APIKey: "key", BaseURL: "https://test.com"})
+	require.NoError(t, providerRepo.Create(&domain.Provider{ID: "p1", Name: "P1", APIKey: "key", BaseURL: "https://test.com"}))
 	model := &domain.Model{ProviderID: "p1", ModelName: "gpt-4"}
 	require.NoError(t, svc.Create(model))
 
@@ -75,7 +75,7 @@ func TestModelService_Update_ProviderID_Invalid(t *testing.T) {
 	modelRepo := repository.NewModelRepository(db)
 	svc := NewModelService(modelRepo, providerRepo)
 
-	providerRepo.Create(&domain.Provider{ID: "p1", Name: "P1", APIKey: "key", BaseURL: "https://test.com"})
+	require.NoError(t, providerRepo.Create(&domain.Provider{ID: "p1", Name: "P1", APIKey: "key", BaseURL: "https://test.com"}))
 	model := &domain.Model{ProviderID: "p1", ModelName: "gpt-4"}
 	require.NoError(t, svc.Create(model))
 
@@ -89,7 +89,7 @@ func TestModelService_Delete(t *testing.T) {
 	modelRepo := repository.NewModelRepository(db)
 	svc := NewModelService(modelRepo, providerRepo)
 
-	providerRepo.Create(&domain.Provider{ID: "p1", Name: "P1", APIKey: "key", BaseURL: "https://test.com"})
+	require.NoError(t, providerRepo.Create(&domain.Provider{ID: "p1", Name: "P1", APIKey: "key", BaseURL: "https://test.com"}))
 	model := &domain.Model{ProviderID: "p1", ModelName: "gpt-4"}
 	require.NoError(t, svc.Create(model))
 

backend/internal/service/service_test.go

@@ -3,14 +3,15 @@ package service
 import (
 	"errors"
 	"testing"
+	"time"
 
 	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
-	"gorm.io/driver/sqlite"
 	"gorm.io/gorm"
 
-	"nex/backend/internal/config"
+	testHelpers "nex/backend/tests"
+
 	"nex/backend/internal/domain"
 	"nex/backend/internal/repository"
 	appErrors "nex/backend/pkg/errors"
@@ -18,18 +19,7 @@ import (
 
 func setupServiceTestDB(t *testing.T) *gorm.DB {
 	t.Helper()
-	dir := t.TempDir()
-	db, err := gorm.Open(sqlite.Open(dir+"/test.db"), &gorm.Config{})
-	require.NoError(t, err)
-	err = db.AutoMigrate(&config.Provider{}, &config.Model{}, &config.UsageStats{})
-	require.NoError(t, err)
-	t.Cleanup(func() {
-		sqlDB, _ := db.DB()
-		if sqlDB != nil {
-			sqlDB.Close()
-		}
-	})
-	return db
+	return testHelpers.SetupTestDB(t)
 }
 
 // ============ RoutingService - RouteByModelName 测试 ============
@@ -40,9 +30,8 @@ func TestRoutingService_RouteByModelName_Success(t *testing.T) {
 	modelRepo := repository.NewModelRepository(db)
 	svc := NewRoutingService(modelRepo, providerRepo)
 
-	// 创建供应商和模型
-	providerRepo.Create(&domain.Provider{ID: "openai", Name: "OpenAI", APIKey: "key", BaseURL: "https://api.openai.com", Enabled: true})
-	modelRepo.Create(&domain.Model{ID: "m1", ProviderID: "openai", ModelName: "gpt-4", Enabled: true})
+	require.NoError(t, providerRepo.Create(&domain.Provider{ID: "openai", Name: "OpenAI", APIKey: "key", BaseURL: "https://api.openai.com", Enabled: true}))
+	require.NoError(t, modelRepo.Create(&domain.Model{ID: "m1", ProviderID: "openai", ModelName: "gpt-4", Enabled: true}))
 
 	result, err := svc.RouteByModelName("openai", "gpt-4")
 	require.NoError(t, err)
@@ -66,10 +55,9 @@ func TestRoutingService_RouteByModelName_DisabledModel(t *testing.T) {
 	modelRepo := repository.NewModelRepository(db)
 	svc := NewRoutingService(modelRepo, providerRepo)
 
-	// 创建启用的供应商和禁用的模型
-	providerRepo.Create(&domain.Provider{ID: "openai", Name: "OpenAI", APIKey: "key", BaseURL: "https://api.openai.com", Enabled: true})
-	modelRepo.Create(&domain.Model{ID: "m1", ProviderID: "openai", ModelName: "gpt-4", Enabled: true})
-	modelRepo.Update("m1", map[string]interface{}{"enabled": false})
+	require.NoError(t, providerRepo.Create(&domain.Provider{ID: "openai", Name: "OpenAI", APIKey: "key", BaseURL: "https://api.openai.com", Enabled: true}))
+	require.NoError(t, modelRepo.Create(&domain.Model{ID: "m1", ProviderID: "openai", ModelName: "gpt-4", Enabled: true}))
+	require.NoError(t, modelRepo.Update("m1", map[string]interface{}{"enabled": false}))
 
 	_, err := svc.RouteByModelName("openai", "gpt-4")
 	assert.True(t, errors.Is(err, appErrors.ErrModelDisabled))
@@ -81,10 +69,9 @@ func TestRoutingService_RouteByModelName_DisabledProvider(t *testing.T) {
 	modelRepo := repository.NewModelRepository(db)
 	svc := NewRoutingService(modelRepo, providerRepo)
 
-	// 创建启用的供应商和模型，然后禁用供应商
-	providerRepo.Create(&domain.Provider{ID: "openai", Name: "OpenAI", APIKey: "key", BaseURL: "https://api.openai.com", Enabled: true})
-	modelRepo.Create(&domain.Model{ID: "m1", ProviderID: "openai", ModelName: "gpt-4", Enabled: true})
-	providerRepo.Update("openai", map[string]interface{}{"enabled": false})
+	require.NoError(t, providerRepo.Create(&domain.Provider{ID: "openai", Name: "OpenAI", APIKey: "key", BaseURL: "https://api.openai.com", Enabled: true}))
+	require.NoError(t, modelRepo.Create(&domain.Model{ID: "m1", ProviderID: "openai", ModelName: "gpt-4", Enabled: true}))
+	require.NoError(t, providerRepo.Update("openai", map[string]interface{}{"enabled": false}))
 
 	_, err := svc.RouteByModelName("openai", "gpt-4")
 	assert.True(t, errors.Is(err, appErrors.ErrProviderDisabled))
@@ -98,7 +85,7 @@ func TestModelService_Create_GeneratesUUID(t *testing.T) {
 	modelRepo := repository.NewModelRepository(db)
 	svc := NewModelService(modelRepo, providerRepo)
 
-	providerRepo.Create(&domain.Provider{ID: "openai", Name: "OpenAI", APIKey: "key", BaseURL: "https://api.openai.com"})
+	require.NoError(t, providerRepo.Create(&domain.Provider{ID: "openai", Name: "OpenAI", APIKey: "key", BaseURL: "https://api.openai.com"}))
 
 	model := &domain.Model{ProviderID: "openai", ModelName: "gpt-4"}
 	err := svc.Create(model)
@@ -122,7 +109,7 @@ func TestModelService_Create_DuplicateModelName(t *testing.T) {
 	modelRepo := repository.NewModelRepository(db)
 	svc := NewModelService(modelRepo, providerRepo)
 
-	providerRepo.Create(&domain.Provider{ID: "openai", Name: "OpenAI", APIKey: "key", BaseURL: "https://api.openai.com"})
+	require.NoError(t, providerRepo.Create(&domain.Provider{ID: "openai", Name: "OpenAI", APIKey: "key", BaseURL: "https://api.openai.com"}))
 
 	model1 := &domain.Model{ProviderID: "openai", ModelName: "gpt-4"}
 	err := svc.Create(model1)
@@ -179,8 +166,8 @@ func TestModelService_Update_DuplicateModelName(t *testing.T) {
 	modelRepo := repository.NewModelRepository(db)
 	svc := NewModelService(modelRepo, providerRepo)
 
-	providerRepo.Create(&domain.Provider{ID: "openai", Name: "OpenAI", APIKey: "key", BaseURL: "https://api.openai.com"})
-	providerRepo.Create(&domain.Provider{ID: "anthropic", Name: "Anthropic", APIKey: "key", BaseURL: "https://api.anthropic.com"})
+	require.NoError(t, providerRepo.Create(&domain.Provider{ID: "openai", Name: "OpenAI", APIKey: "key", BaseURL: "https://api.openai.com"}))
+	require.NoError(t, providerRepo.Create(&domain.Provider{ID: "anthropic", Name: "Anthropic", APIKey: "key", BaseURL: "https://api.anthropic.com"}))
 
 	model1 := &domain.Model{ProviderID: "openai", ModelName: "gpt-4"}
 	err := svc.Create(model1)
@@ -216,7 +203,7 @@ func TestModelService_Update_Success(t *testing.T) {
 	modelRepo := repository.NewModelRepository(db)
 	svc := NewModelService(modelRepo, providerRepo)
 
-	providerRepo.Create(&domain.Provider{ID: "openai", Name: "OpenAI", APIKey: "key", BaseURL: "https://api.openai.com"})
+	require.NoError(t, providerRepo.Create(&domain.Provider{ID: "openai", Name: "OpenAI", APIKey: "key", BaseURL: "https://api.openai.com"}))
 
 	model := &domain.Model{ProviderID: "openai", ModelName: "gpt-4"}
 	err := svc.Create(model)
@@ -272,3 +259,223 @@ func TestProviderService_Update_Success(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, "OpenAI Updated", updated.Name)
 }
+
+// ============ StatsService - Aggregate ByModel 测试 ============
+
+func TestStatsService_Aggregate_ByModel(t *testing.T) {
+	tests := []struct {
+		name     string
+		stats    []domain.UsageStats
+		expected []map[string]interface{}
+	}{
+		{
+			name: "multiple providers with same model name",
+			stats: []domain.UsageStats{
+				{ProviderID: "openai", ModelName: "gpt-4", RequestCount: 10},
+				{ProviderID: "azure", ModelName: "gpt-4", RequestCount: 20},
+				{ProviderID: "openai", ModelName: "gpt-4", RequestCount: 5},
+			},
+			expected: []map[string]interface{}{
+				{"provider_id": "openai", "model_name": "gpt-4", "request_count": 15},
+				{"provider_id": "azure", "model_name": "gpt-4", "request_count": 20},
+			},
+		},
+		{
+			name: "empty providerID",
+			stats: []domain.UsageStats{
+				{ProviderID: "", ModelName: "gpt-4", RequestCount: 10},
+				{ProviderID: "", ModelName: "gpt-4", RequestCount: 5},
+			},
+			expected: []map[string]interface{}{
+				{"provider_id": "", "model_name": "gpt-4", "request_count": 15},
+			},
+		},
+		{
+			name:     "empty result set",
+			stats:    []domain.UsageStats{},
+			expected: []map[string]interface{}{},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			db := setupServiceTestDB(t)
+			statsRepo := repository.NewStatsRepository(db)
+			svc := NewStatsService(statsRepo)
+
+			result := svc.Aggregate(tt.stats, "model")
+
+			assert.Len(t, result, len(tt.expected))
+			for _, exp := range tt.expected {
+				found := false
+				for _, r := range result {
+					if r["provider_id"] == exp["provider_id"] && r["model_name"] == exp["model_name"] {
+						assert.Equal(t, exp["request_count"], r["request_count"])
+						found = true
+						break
+					}
+				}
+				assert.True(t, found, "expected result not found: %v", exp)
+			}
+		})
+	}
+}
+
+// ============ StatsService - Aggregate ByDate 测试 ============
+
+func TestStatsService_Aggregate_ByDate(t *testing.T) {
+	tests := []struct {
+		name     string
+		stats    []domain.UsageStats
+		expected []map[string]interface{}
+	}{
+		{
+			name: "normal date grouping",
+			stats: []domain.UsageStats{
+				{Date: time.Date(2024, 1, 1, 0, 0, 0, 0, time.UTC), RequestCount: 10},
+				{Date: time.Date(2024, 1, 1, 12, 0, 0, 0, time.UTC), RequestCount: 5},
+				{Date: time.Date(2024, 1, 2, 0, 0, 0, 0, time.UTC), RequestCount: 20},
+			},
+			expected: []map[string]interface{}{
+				{"date": "2024-01-01", "request_count": 15},
+				{"date": "2024-01-02", "request_count": 20},
+			},
+		},
+		{
+			name: "zero-value time",
+			stats: []domain.UsageStats{
+				{Date: time.Time{}, RequestCount: 10},
+				{Date: time.Time{}, RequestCount: 5},
+			},
+			expected: []map[string]interface{}{
+				{"date": "0001-01-01", "request_count": 15},
+			},
+		},
+		{
+			name:     "empty result set",
+			stats:    []domain.UsageStats{},
+			expected: []map[string]interface{}{},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			db := setupServiceTestDB(t)
+			statsRepo := repository.NewStatsRepository(db)
+			svc := NewStatsService(statsRepo)
+
+			result := svc.Aggregate(tt.stats, "date")
+
+			assert.Len(t, result, len(tt.expected))
+			for _, exp := range tt.expected {
+				found := false
+				for _, r := range result {
+					if r["date"] == exp["date"] {
+						assert.Equal(t, exp["request_count"], r["request_count"])
+						found = true
+						break
+					}
+				}
+				assert.True(t, found, "expected result not found: %v", exp)
+			}
+		})
+	}
+}
+
+// ============ ProviderService - isUniqueConstraintError 测试 ============
+
+func TestProviderService_isUniqueConstraintError(t *testing.T) {
+	tests := []struct {
+		name     string
+		err      error
+		expected bool
+	}{
+		{
+			name:     "nil error",
+			err:      nil,
+			expected: false,
+		},
+		{
+			name:     "UNIQUE constraint failed",
+			err:      errors.New("UNIQUE constraint failed"),
+			expected: true,
+		},
+		{
+			name:     "duplicate key value",
+			err:      errors.New("duplicate key value"),
+			expected: true,
+		},
+		{
+			name:     "UNIQUE constraint case insensitive",
+			err:      errors.New("unique constraint violation"),
+			expected: true,
+		},
+		{
+			name:     "other error",
+			err:      errors.New("some other error"),
+			expected: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := isUniqueConstraintError(tt.err)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+// ============ ProviderService - List MaskAPIKey 测试 ============
+
+func TestProviderService_List_MaskAPIKey(t *testing.T) {
+	db := setupServiceTestDB(t)
+	repo := repository.NewProviderRepository(db)
+	modelRepo := repository.NewModelRepository(db)
+	svc := NewProviderService(repo, modelRepo)
+
+	provider1 := &domain.Provider{ID: "openai", Name: "OpenAI", APIKey: "sk-1234567890", BaseURL: "https://api.openai.com"}
+	provider2 := &domain.Provider{ID: "anthropic", Name: "Anthropic", APIKey: "sk-anthropic1234", BaseURL: "https://api.anthropic.com"}
+	require.NoError(t, svc.Create(provider1))
+	require.NoError(t, svc.Create(provider2))
+
+	providers, err := svc.List()
+	require.NoError(t, err)
+	require.Len(t, providers, 2)
+
+	for _, p := range providers {
+		assert.Contains(t, p.APIKey, "***")
+		assert.Len(t, p.APIKey, 7)
+	}
+}
+
+func TestModelService_ConcurrentCreate(t *testing.T) {
+	db := setupServiceTestDB(t)
+	providerRepo := repository.NewProviderRepository(db)
+	modelRepo := repository.NewModelRepository(db)
+	svc := NewModelService(modelRepo, providerRepo)
+
+	require.NoError(t, providerRepo.Create(&domain.Provider{ID: "openai", Name: "OpenAI", APIKey: "key", BaseURL: "https://api.openai.com"}))
+
+	results := make(chan error, 2)
+	for i := 0; i < 2; i++ {
+		go func() {
+			model := &domain.Model{ProviderID: "openai", ModelName: "gpt-4"}
+			results <- svc.Create(model)
+		}()
+	}
+
+	err1 := <-results
+	err2 := <-results
+
+	successCount := 0
+	errorCount := 0
+	for _, err := range []error{err1, err2} {
+		if err == nil {
+			successCount++
+		} else {
+			errorCount++
+		}
+	}
+	assert.Equal(t, 1, successCount)
+	assert.Equal(t, 1, errorCount)
+}

backend/internal/service/stats_service.go

@@ -6,6 +6,8 @@ import (
 	"nex/backend/internal/domain"
 )
 
+//go:generate go run go.uber.org/mock/mockgen -source=stats_service.go -destination=../../tests/mocks/mock_stats_service.go -package=mocks
+
 // StatsService 统计服务接口
 type StatsService interface {
 	Record(providerID, modelName string) error