Fraud Detection Test Suite - Quick Reference¶

📋 Test Suite Overview¶

Metric	Value
Test File	`backend/tests/test_14_fraud_detection.py`
Total Lines	~650
Test Classes	5
Test Methods	40+
Endpoints Covered	14
New Fixtures	6

🧪 Test Breakdown¶

Fraud Rule Management (13 tests)¶

✓ Create rule - identity category
✓ Create rule - behavior category
✓ Create rule - document category
✓ Create rule - financial category
✓ Create rule - with conditions
✓ Fetch all rules
✓ Fetch rules - filter by active
✓ Fetch rules - filter by category
✓ Get single rule by ID
✓ Edit existing rule
✓ Toggle rule - deactivate
✓ Toggle rule - activate
✓ Delete rule
+ 3 validation error tests

Fraud Detection Check (3 tests)¶

✓ Check application - no fraud
✓ Check application - with fraud flag
✓ Check application - invalid ID error

Fraud Flag Management (11 tests)¶

✓ Fetch flags - no filters
✓ Fetch flags - by status (open)
✓ Fetch flags - by status (escalated)
✓ Fetch flags - by risk level
✓ Get single flag
✓ Get flag - with customer details
✓ Mark false positive
✓ Confirm fraud
✓ Escalate flag
✓ Mark false positive - with empty notes
+ 2 error handling tests

Integration Tests (6 tests)¶

✓ Fraud workflow - detection to escalation
✓ Fraud workflow - rule-based detection
✓ Fraud detection - high risk score
✓ Fraud detection - multiple rules
✓ Flag lifecycle - complete workflow
✓ Fraud detection - caching consistency

Error Handling (4 tests)¶

✓ Duplicate rule name
✓ Edit non-existent rule
✓ Get non-existent flag
✓ Missing required fields

🔧 Fixtures Available¶

In `conftest.py`:¶

Fixture Name	Purpose	Scope
`create_fraud_rule_data`	Basic rule creation template	function
`create_fraud_rule_data_with_conditions`	Rule with conditions	function
`test_fraud_rule`	Persistent test rule	session
`test_fraud_flag`	Persistent test flag	session
`test_fraud_flag_with_customer`	Flag with customer info	function
`test_loan_application_with_fraud_flag`	App with flag	function

Usage Example:¶

def test_my_fraud_feature(
    client: TestClient,
    superuser_auth_headers: Dict[str, str],
    test_fraud_rule: LoanFraudRule,
    create_fraud_rule_data: Dict[str, any],
):
    # Use fixtures in your test
    pass

📊 Tested Fraud Categories¶

┌─────────────┐
│  identity   │  Identity fraud detection
└─────────────┘

┌─────────────┐
│  behavior   │  Behavioral anomalies
└─────────────┘

┌─────────────┐
│  document   │  Document-based fraud
└─────────────┘

┌─────────────┐
│  financial  │  Financial irregularities
└─────────────┘

┌──────────────┐
│ application  │  Application-level fraud
└──────────────┘

🎯 Expected Responses¶

Successful Rule Creation (201)¶

{
  "id": 1,
  "name": "Identity Fraud Rule",
  "category": "identity",
  "risk_score": 75,
  "action": "flag",
  "severity": "high",
  "is_active": true,
  "priority": 1
}

List Response (200)¶

{
  "rules": [...],
  "pagination": {
    "page": 1,
    "page_size": 10,
    "total": 25
  }
}

Fraud Flag Response (200)¶

{
  "id": 1,
  "risk_score": 80.0,
  "risk_level": "high",
  "status": "open",
  "flag_reason": "Suspicious activity",
  "fraudster": { ... }
}

Error Response (404)¶

{
  "detail": "Rule not found"
}

🚀 Running Tests¶

All fraud detection tests:¶

pytest backend/tests/test_14_fraud_detection.py -v

Specific test class:¶

pytest backend/tests/test_14_fraud_detection.py::TestFraudRuleManagement -v

Single test:¶

pytest backend/tests/test_14_fraud_detection.py::TestFraudRuleManagement::test_create_fraud_rule_identity_category -v

With coverage:¶

pytest backend/tests/test_14_fraud_detection.py --cov=routers.loan --cov-report=term-missing

Watch mode (with pytest-watch):¶

ptw backend/tests/test_14_fraud_detection.py -- -v

📝 Test Pattern Examples¶

Testing Valid Input:¶

def test_create_fraud_rule_identity_category(
    client: TestClient,
    superuser_auth_headers: Dict[str, str],
    create_fraud_rule_data: Dict[str, any],
):
    rule_data = create_fraud_rule_data.copy()
    rule_data["name"] = f"Rule {random.randint(1000, 9999)}"
    rule_data["category"] = "identity"

    response = client.post(
        "/api/v1/loan/fraudrule/add",
        headers=superuser_auth_headers,
        json=rule_data,
    )
    assert response.status_code == 201
    data = response.json()
    assert data["category"] == "identity"

Testing Invalid Input:¶

def test_create_fraud_rule_invalid_category(
    client: TestClient,
    superuser_auth_headers: Dict[str, str],
    create_fraud_rule_data: Dict[str, any],
):
    rule_data = create_fraud_rule_data.copy()
    rule_data["category"] = "invalid_category"

    response = client.post(
        "/api/v1/loan/fraudrule/add",
        headers=superuser_auth_headers,
        json=rule_data,
    )
    assert response.status_code in [400, 422]

Testing Integration Workflow:¶

def test_fraud_workflow_detection_to_escalation(
    client: TestClient,
    superuser_auth_headers: Dict[str, str],
    test_loan_application: LoanApplication,
):
    # Step 1: Run fraud check
    response = client.post(
        "/api/v1/loan/fraud/check",
        headers=superuser_auth_headers,
        json={"application_id": test_loan_application.id},
    )
    assert response.status_code in [200, 201]

🔍 Fraud Flag Lifecycle¶

┌─────────┐
│  CREATE │  System creates flag after rule match
└────┬────┘
     ↓
┌─────────────┐
│    OPEN     │  Flag awaits review
└────┬────────┘
     ↓
┌──────────────────┐
│  ESCALATED/UNDER │  Manual review or escalation
│     REVIEW      │
└────┬─────────────┘
     ↓
┌──────────┬──────────────┐
│          │              │
v          v              v
RESOLVED   FALSE_POS   AUTO_BLOCKED
(Fraud)    (Error)     (System Action)

📚 Additional Documentation¶

Full details: FRAUD_DETECTION_TESTS.md
API Reference: See routers/loan.py endpoints
Models: See models/loan.py
Test Data: tests/data/add_fraud_rule_data.json

✨ Key Features Tested¶

✅ Multiple fraud categories
✅ Complex rule conditions
✅ Filtering and pagination
✅ Rule activation/deactivation
✅ Fraud flag state transitions
✅ False positive handling
✅ Escalation workflows
✅ Error scenarios
✅ Integration workflows
✅ Data validation

🐛 Troubleshooting¶

Tests Won't Run¶

Issue: Import error with socket.py
Cause: Module name conflicts with stdlib
Status: Pre-existing issue, not related to fraud tests
Solution: Rename routers/socket.py to routers/ws_socket.py

Fixture Not Found¶

Issue: test_fraud_rule fixture not available
Solution: Ensure conftest.py is updated with new fixtures
Check: Verify import of LoanFraudRule in conftest

Test Data Missing¶

Issue: add_fraud_rule_data.json not found
Location: backend/tests/data/add_fraud_rule_data.json
Status: File exists and has been updated with proper schema

📦 Files Modified/Created¶

File	Action	Purpose
`test_14_fraud_detection.py`	✅ Created	Main test suite
`conftest.py`	✅ Updated	Added 6 fixtures
`add_fraud_rule_data.json`	✅ Updated	Updated schema
`FRAUD_DETECTION_TESTS.md`	✅ Created	Full documentation