# Image Handler Test Summary

## Task 4.2: 实现图片删除和获取API

### Implementation Status
✅ **COMPLETE** - All endpoints are implemented and fully tested

### Endpoints Tested

#### 1. GET /api/v1/images/:id
**Purpose**: Retrieve an image file by ID  
**Requirements**: 4.8

**Test Coverage**:
- ✅ Success case - returns image file
- ✅ Invalid image ID - returns 400 Bad Request
- ✅ Image not found - returns 404 Not Found
- ✅ Internal error handling - returns 500 Internal Server Error

#### 2. GET /api/v1/transactions/:id/images
**Purpose**: Retrieve all images for a transaction  
**Requirements**: 4.8

**Test Coverage**:
- ✅ Success case - returns list of images
- ✅ Invalid transaction ID - returns 400 Bad Request
- ✅ Transaction not found - returns 404 Not Found
- ✅ Empty list - returns empty array successfully
- ✅ Internal error handling

#### 3. DELETE /api/v1/transactions/:id/images/:imageId
**Purpose**: Delete an image attachment  
**Requirements**: 4.7

**Test Coverage**:
- ✅ Success case - returns 204 No Content
- ✅ Invalid transaction ID - returns 400 Bad Request
- ✅ Invalid image ID - returns 400 Bad Request
- ✅ Image not found - returns 404 Not Found
- ✅ Image belongs to different transaction - returns 404 Not Found
- ✅ Internal error handling - returns 500 Internal Server Error

#### 4. POST /api/v1/transactions/:id/images
**Purpose**: Upload an image attachment  
**Requirements**: 4.3, 4.4, 4.9-4.13

**Test Coverage**:
- ✅ Success case with default compression
- ✅ Success with low compression (800px)
- ✅ Success with medium compression (1200px)
- ✅ Success with high compression (original)
- ✅ Invalid compression level - returns 400 Bad Request
- ✅ Invalid transaction ID - returns 400 Bad Request
- ✅ No file provided - returns 400 Bad Request
- ✅ Invalid image format - returns 400 Bad Request
- ✅ Image too large (>10MB) - returns 413 Request Entity Too Large
- ✅ Max images exceeded (>9) - returns 400 Bad Request
- ✅ Transaction not found - returns 404 Not Found

### Error Handling Tests
✅ All error types properly handled:
- Invalid image format error
- Image too large error
- Max images exceeded error
- Transaction not found error
- Image not found error
- Generic internal errors

### Test Statistics
- **Total Tests**: 26
- **Passed**: 26
- **Failed**: 0
- **Coverage**: Comprehensive coverage of all endpoints and error scenarios

### Validation Against Requirements

#### Requirement 4.7: Image Deletion
✅ DELETE endpoint implemented and tested
✅ Proper authorization (image belongs to transaction)
✅ File system cleanup on deletion
✅ Database record removal

#### Requirement 4.8: Image Retrieval
✅ GET single image endpoint implemented
✅ GET transaction images list endpoint implemented
✅ Proper file serving
✅ Error handling for missing images

### Notes
- Tests use mock service to isolate handler logic
- All tests follow existing project patterns (similar to ledger_handler_test.go)
- Response format matches API package structure (success/error with nested fields)
- Comprehensive error scenario coverage ensures robust error handling