test: 프론트엔드/백엔드 테스트 커버리지 및 시나리오 보강 (Issue #291)

- FE: Vitest 환경 구축 및 공통 UI 컴포넌트(Badge, Button) 테스트 추가
- FE: Playwright E2E 테스트(Auth, Tenant CRUD 및 Validation) 시나리오 보강
- BE: Testcontainers 기반 Repository 통합 테스트(PostgreSQL) 추가
- BE: TenantRepository 계층 구조(Hierarchy), DB 제약조건(Unique) 테스트
- BE: UserRepository 통합 테스트(CRUD, Delete) 추가
- BE: PasswordPolicy 유틸리티 테스트 보강
- BE: TenantService 엣지 케이스(중복 슬러그, 권한 등) 검증 로직 추가
- Fix: 하위 테넌트 생성 시 ParentID 누락 문제 해결

backend/internal/service/tenant_service_edge_test.go

@@ -0,0 +1,115 @@
+package service
+
+import (
+	"baron-sso-backend/internal/domain"
+	"context"
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+	"gorm.io/gorm"
+)
+
+func TestTenantService_RegisterTenant_DuplicateSlug(t *testing.T) {
+	mockRepo := new(MockTenantRepoForSvc)
+	svc := NewTenantService(mockRepo, nil, nil)
+
+	ctx := context.Background()
+	slug := "duplicate-slug"
+
+	// Mock: slug already exists
+	mockRepo.On("FindBySlug", ctx, slug).Return(&domain.Tenant{ID: "existing-id", Slug: slug}, nil)
+
+	tenant, err := svc.RegisterTenant(ctx, "New Name", slug, "", nil, nil)
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "already exists")
+	assert.Nil(t, tenant)
+}
+
+func TestTenantService_RegisterTenant_InvalidSlug(t *testing.T) {
+	svc := NewTenantService(nil, nil, nil)
+	ctx := context.Background()
+
+	// Case 1: Too short
+	_, err := svc.RegisterTenant(ctx, "Name", "a", "", nil, nil)
+	assert.Error(t, err)
+
+	// Case 2: Invalid characters
+	_, err = svc.RegisterTenant(ctx, "Name", "Invalid Slug!", "", nil, nil)
+	assert.Error(t, err)
+}
+
+func TestTenantService_RequestRegistration_EmailMismatch(t *testing.T) {
+	svc := NewTenantService(nil, nil, nil)
+	ctx := context.Background()
+
+	// admin email domain (gmail.com) != tenant domain (company.com)
+	tenant, err := svc.RequestRegistration(ctx, "Name", "slug", "", "company.com", "admin@gmail.com")
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "must match")
+	assert.Nil(t, tenant)
+}
+
+func TestTenantService_ApproveTenant_NotFound(t *testing.T) {
+	mockRepo := new(MockTenantRepoForSvc)
+	svc := NewTenantService(mockRepo, nil, nil)
+
+	ctx := context.Background()
+	id := "non-existent-id"
+
+	mockRepo.On("FindByID", ctx, id).Return(nil, gorm.ErrRecordNotFound)
+
+	err := svc.ApproveTenant(ctx, id)
+	assert.Error(t, err)
+	assert.True(t, errors.Is(err, gorm.ErrRecordNotFound))
+}
+
+func TestTenantService_GetTenantByDomain_Inactive(t *testing.T) {
+	mockRepo := new(MockTenantRepoForSvc)
+	svc := NewTenantService(mockRepo, nil, nil)
+
+	ctx := context.Background()
+	domainName := "inactive.com"
+
+	mockRepo.On("FindByDomain", ctx, domainName).Return(&domain.Tenant{
+		ID:     "t1",
+		Status: domain.TenantStatusPending,
+	}, nil)
+
+	tenant, err := svc.GetTenantByDomain(ctx, domainName)
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "not active")
+	assert.Nil(t, tenant)
+}
+
+func TestTenantService_ApproveTenant_UserNotFound(t *testing.T) {
+	mockRepo := new(MockTenantRepoForSvc)
+	mockUserRepo := new(MockUserRepoForTenant)
+	mockOutbox := new(MockKetoOutboxRepositoryShared)
+
+	svc := NewTenantService(mockRepo, mockUserRepo, mockOutbox)
+	ctx := context.Background()
+	tenantID := "t1"
+	adminEmail := "notfound@tenant.com"
+
+	tenant := &domain.Tenant{
+		ID:     tenantID,
+		Slug:   "tenant-slug",
+		Config: domain.JSONMap{"adminEmail": adminEmail},
+	}
+
+	mockRepo.On("FindByID", ctx, tenantID).Return(tenant, nil)
+	mockRepo.On("Update", ctx, mock.Anything).Return(nil)
+	// User not found in DB
+	mockUserRepo.On("FindByEmail", adminEmail).Return(nil, gorm.ErrRecordNotFound)
+	
+	// Outbox should not be called since user is not found
+	
+	err := svc.ApproveTenant(ctx, tenantID)
+	assert.NoError(t, err) // Should succeed but just log that user is not found
+	mockRepo.AssertExpectations(t)
+	mockUserRepo.AssertExpectations(t)
+	mockOutbox.AssertNotCalled(t, "Create")
+}
+