M-T-B-A/business-operator-frontend/docs/TASK_4.3_COMPLETION.md

Task 4.3 Completion Report: MockRefundService Implementation

Overview

Successfully implemented the MockRefundService for the merchant portal, providing complete mock functionality for refund/after-sales management operations.

Deliverables

1. MockRefundService Implementation

File: src/app/mock/services/mock-refund.service.ts

Features Implemented:

• ✅ getRefunds(pagination?) - Retrieve paginated list of refunds
• ✅ getRefund(refundNo) - Get individual refund by refund number
• ✅ approveRefund(refundNo) - Approve pending refunds
• ✅ rejectRefund(refundNo, reason) - Reject refunds with reason
• ✅ API delay simulation (200-500ms)
• ✅ Status validation (only Pending refunds can be approved/rejected)
• ✅ Comprehensive error handling
• ✅ Helper methods for testing and metrics

Initial Data:

• 50 mock refunds total
  • 20 Pending refunds
  • 20 Approved refunds
  • 10 Rejected refunds
• All sorted by creation date (newest first)

2. Comprehensive Test Suite

File: src/app/mock/services/mock-refund.service.spec.ts

Test Coverage:

• ✅ Service creation
• ✅ Get all refunds without pagination
• ✅ Get paginated refunds (page 1 and page 2)
• ✅ Sorting verification (newest first)
• ✅ API delay simulation
• ✅ Get single refund by refund number
• ✅ Error handling for non-existent refunds
• ✅ Immutability verification (returns copies)
• ✅ Approve pending refund workflow
• ✅ Update refund in list after approval
• ✅ Error handling for approving non-pending refunds
• ✅ Reject pending refund with reason
• ✅ Update refund in list after rejection
• ✅ Error handling for empty rejection reason
• ✅ Error handling for whitespace-only rejection reason
• ✅ Error handling for rejecting non-pending refunds
• ✅ Reset functionality
• ✅ Get all refunds helper
• ✅ Get refund count by status
• ✅ Data structure validation
• ✅ Refund amount validation

Test Results:

• All 73 tests passing (including existing tests)
• 0 failures
• Comprehensive coverage of all service methods

3. Documentation

Files Created:

• README_REFUND_SERVICE.md - Complete API documentation with examples
• verify-refund-service.ts - Verification script demonstrating all features
• Updated README.md - Added MockRefundService to main services documentation

Documentation Includes:

• Complete API reference for all methods
• Usage examples for each method
• Data model definitions
• Error handling documentation
• Integration notes
• Testing information
• Requirements validation

Requirements Validated

Requirement 14.1-14.3: Refund List Display

✅ 14.1: Display refund list showing application time, refund reason, refund amount, and status ✅ 14.2: Clearly indicate refund status as pending review, approved, or rejected ✅ 14.3: Display refund type as refund only or return goods

Implementation:

• getRefunds() method returns complete refund data including all required fields
• Pagination support for efficient list display
• Sorting by creation date (newest first)

Requirement 15.1-15.3: Refund Approval/Rejection

✅ 15.1: When merchant approves refund, trigger refund process ✅ 15.2: When merchant rejects refund, require rejection reason ✅ 15.3: When refund decision is submitted, update status and display confirmation

Implementation:

• approveRefund() method updates status to Approved and sets processedAt timestamp
• rejectRefund() method requires non-empty reason and updates status to Rejected
• Both methods validate that only Pending refunds can be processed
• Comprehensive error handling for invalid operations

Requirement 23.2: API Delay Simulation

✅ Simulate API response delays (200-500ms) for realistic user experience

Implementation:

• All methods use delay() operator with random 200-500ms delay
• Provides realistic loading state testing

Requirement 23.3: CRUD Operations with Local State

✅ Provide CRUD operations on mock data with local state management

Implementation:

• In-memory array maintains refund state
• All operations update the local state
• Immutable updates (returns copies, not references)
• Helper methods for state inspection and reset

Technical Implementation Details

Service Architecture

@Injectable({ providedIn: 'root' })
export class MockRefundService {
  private refunds: Refund[] = [];
  
  // Core methods
  getRefunds(pagination?): Observable<RefundListResponse>
  getRefund(refundNo): Observable<Refund>
  approveRefund(refundNo): Observable<Refund>
  rejectRefund(refundNo, reason): Observable<Refund>
  
  // Helper methods
  reset(): void
  getAllRefunds(): Refund[]
  getRefundCountByStatus(status): number
}

Key Features

1. Status Validation

   • Only Pending refunds can be approved or rejected
   • Throws descriptive errors for invalid status transitions

2. Reason Validation

   • Rejection requires non-empty reason
   • Trims whitespace and validates length

3. Timestamp Management

   • Sets processedAt when refund is approved or rejected
   • Maintains createdAt for all refunds

4. Immutability

   • All methods return copies of data
   • Prevents external modification of internal state

5. Error Handling

   • Descriptive error messages
   • Proper error propagation through Observables

Testing Results

Unit Tests

MockRefundService
  ✓ should be created
  
  getRefunds
    ✓ should return all refunds without pagination
    ✓ should return paginated refunds
    ✓ should return second page of refunds
    ✓ should sort refunds by creation date (newest first)
    ✓ should simulate API delay
  
  getRefund
    ✓ should return a specific refund by refund number
    ✓ should throw error for non-existent refund
    ✓ should return a copy of the refund (not reference)
  
  approveRefund
    ✓ should approve a pending refund
    ✓ should update refund in the list
    ✓ should throw error when approving non-pending refund
    ✓ should throw error for non-existent refund
  
  rejectRefund
    ✓ should reject a pending refund with reason
    ✓ should update refund in the list
    ✓ should throw error when rejecting without reason
    ✓ should throw error when rejecting with whitespace-only reason
    ✓ should throw error when rejecting non-pending refund
    ✓ should throw error for non-existent refund
  
  Helper methods
    ✓ should reset refunds to initial state
    ✓ should return all refunds
    ✓ should return copy of refunds array
    ✓ should count refunds by status
  
  Data integrity
    ✓ should maintain refund data structure
    ✓ should have valid refund amounts

Total: 73 tests passing

Code Quality

TypeScript Compliance

• ✅ No TypeScript errors
• ✅ Full type safety with interfaces
• ✅ Proper use of enums for status and type
• ✅ Observable return types for async operations

Best Practices

• ✅ Injectable service with root provider
• ✅ RxJS operators for async handling
• ✅ Immutable data patterns
• ✅ Comprehensive error handling
• ✅ Clear method naming
• ✅ Detailed JSDoc comments

Code Organization

• ✅ Logical method grouping
• ✅ Private helper methods
• ✅ Consistent code style
• ✅ Proper imports and exports

Integration Points

Data Models Used

• Refund interface from core/models/refund.model.ts
• RefundType enum (OnlyRefund, ReturnGoods)
• RefundStatus enum (Pending, Approved, Rejected)

Data Generators Used

• generateRefund() from mock/data/refund.generator.ts
• generateRefunds() for bulk generation

Service Pattern

• Follows same pattern as MockOrderService and MockProductService
• Consistent API design across all mock services
• Observable-based for Angular integration

Usage Example

import { MockRefundService } from './mock/services/mock-refund.service';
import { RefundStatus } from './core/models/refund.model';

@Component({...})
export class RefundListComponent {
  constructor(private refundService: MockRefundService) {}
  
  loadRefunds() {
    const pagination = { page: 1, pageSize: 10, total: 0 };
    this.refundService.getRefunds(pagination).subscribe(response => {
      this.refunds = response.data;
      this.totalRefunds = response.total;
    });
  }
  
  approveRefund(refundNo: string) {
    this.refundService.approveRefund(refundNo).subscribe(
      updated => {
        this.showSuccess('退款已批准');
        this.loadRefunds();
      },
      error => this.showError(error.message)
    );
  }
  
  rejectRefund(refundNo: string, reason: string) {
    this.refundService.rejectRefund(refundNo, reason).subscribe(
      updated => {
        this.showSuccess('退款已拒绝');
        this.loadRefunds();
      },
      error => this.showError(error.message)
    );
  }
}

Next Steps

The MockRefundService is now ready for integration with UI components:

1. RefundListComponent (Task 11.1-11.2)

   • Use getRefunds() for list display
   • Use getRefundCountByStatus() for metrics

2. RefundApprovalComponent (Task 11.3)

   • Use approveRefund() for approval workflow
   • Use rejectRefund() for rejection workflow

3. DashboardComponent (Task 6.1)

   • Use getRefundCountByStatus(RefundStatus.Pending) for pending refund count metric

Files Created/Modified

Created

1. src/app/mock/services/mock-refund.service.ts (185 lines)
2. src/app/mock/services/mock-refund.service.spec.ts (280 lines)
3. src/app/mock/services/README_REFUND_SERVICE.md (550 lines)
4. src/app/mock/services/verify-refund-service.ts (150 lines)
5. docs/TASK_4.3_COMPLETION.md (this file)

Modified

1. src/app/mock/services/README.md - Added MockRefundService documentation

Summary

Task 4.3 has been successfully completed with:

• ✅ Full implementation of MockRefundService
• ✅ All required methods implemented
• ✅ API delay simulation (200-500ms)
• ✅ Comprehensive test suite (all tests passing)
• ✅ Complete documentation
• ✅ Requirements validation (14.1-14.3, 15.1-15.3, 23.2, 23.3)
• ✅ No TypeScript errors
• ✅ Ready for UI component integration

The service provides a solid foundation for refund management features in the merchant portal and follows the established patterns from MockProductService and MockOrderService.