Zero Script QA Expert Knowledge

Overview

Zero Script QA is a methodology that verifies features through structured logs and real-time monitoring without writing test scripts.

Traditional: Write test code → Execute → Check results → Maintain
Zero Script: Build log infrastructure → Manual UX test → AI log analysis → Auto issue detection

Core Principles

1. Log Everything

All API calls (including 200 OK)
All errors
All important business events
Entire flow trackable via Request ID

2. Structured JSON Logs

Parseable JSON format
Consistent fields (timestamp, level, request_id, message, data)
Different log levels per environment

3. Real-time Monitoring

Docker log streaming
Claude Code analyzes in real-time
Immediate issue detection and documentation

Logging Architecture

JSON Log Format Standard

{
  "timestamp": "2026-01-08T10:30:00.000Z",
  "level": "INFO",
  "service": "api",
  "request_id": "req_abc123",
  "message": "API Request completed",
  "data": {
    "method": "POST",
    "path": "/api/users",
    "status": 200,
    "duration_ms": 45
  }
}

Required Log Fields

Field	Type	Description
timestamp	ISO 8601	Time of occurrence
level	string	DEBUG, INFO, WARNING, ERROR
service	string	Service name (api, web, worker, etc.)
request_id	string	Request tracking ID
message	string	Log message
data	object	Additional data (optional)

Log Level Policy

Environment	Minimum Level	Purpose
Local	DEBUG	Development and QA
Staging	DEBUG	QA and integration testing
Production	INFO	Operations monitoring

Request ID Propagation

Concept

Client → API Gateway → Backend → Database
   ↓         ↓           ↓          ↓
req_abc   req_abc     req_abc    req_abc

Trackable with same Request ID across all layers

Implementation Patterns

1. Request ID Generation (Entry Point)

// middleware.ts
import { v4 as uuidv4 } from 'uuid';

export function generateRequestId(): string {
  return `req_${uuidv4().slice(0, 8)}`;
}

// Propagate via header
headers['X-Request-ID'] = requestId;

2. Request ID Extraction and Propagation

// API client
const requestId = headers['X-Request-ID'] || generateRequestId();

// Include in all logs
logger.info('Processing request', { request_id: requestId });

// Include in header when calling downstream services
await fetch(url, {
  headers: { 'X-Request-ID': requestId }
});

Backend Logging (FastAPI)

Logging Middleware

# middleware/logging.py
import logging
import time
import uuid
import json
from fastapi import Request

class JsonFormatter(logging.Formatter):
    def format(self, record):
        log_record = {
            "timestamp": self.formatTime(record),
            "level": record.levelname,
            "service": "api",
            "request_id": getattr(record, 'request_id', 'N/A'),
            "message": record.getMessage(),
        }
        if hasattr(record, 'data'):
            log_record["data"] = record.data
        return json.dumps(log_record)

class LoggingMiddleware:
    async def __call__(self, request: Request, call_next):
        request_id = request.headers.get('X-Request-ID', f'req_{uuid.uuid4().hex[:8]}')
        request.state.request_id = request_id

        start_time = time.time()

        # Request logging
        logger.info(
            f"Request started",
            extra={
                'request_id': request_id,
                'data': {
                    'method': request.method,
                    'path': request.url.path,
                    'query': str(request.query_params)
                }
            }
        )

        response = await call_next(request)

        duration = (time.time() - start_time) * 1000

        # Response logging (including 200 OK!)
        logger.info(
            f"Request completed",
            extra={
                'request_id': request_id,
                'data': {
                    'status': response.status_code,
                    'duration_ms': round(duration, 2)
                }
            }
        )

        response.headers['X-Request-ID'] = request_id
        return response

Business Logic Logging

# services/user_service.py
def create_user(data: dict, request_id: str):
    logger.info("Creating user", extra={
        'request_id': request_id,
        'data': {'email': data['email']}
    })

    # Business logic
    user = User(**data)
    db.add(user)
    db.commit()

    logger.info("User created", extra={
        'request_id': request_id,
        'data': {'user_id': user.id}
    })

    return user

Frontend Logging (Next.js)

Logger Module

// lib/logger.ts
type LogLevel = 'DEBUG' | 'INFO' | 'WARNING' | 'ERROR';

interface LogData {
  request_id?: string;
  [key: string]: any;
}

const LOG_LEVELS: Record<LogLevel, number> = {
  DEBUG: 0,
  INFO: 1,
  WARNING: 2,
  ERROR: 3,
};

const MIN_LEVEL = process.env.NODE_ENV === 'production' ? 'INFO' : 'DEBUG';

function log(level: LogLevel, message: string, data?: LogData) {
  if (LOG_LEVELS[level] < LOG_LEVELS[MIN_LEVEL]) return;

  const logEntry = {
    timestamp: new Date().toISOString(),
    level,
    service: 'web',
    request_id: data?.request_id || 'N/A',
    message,
    data: data ? { ...data, request_id: undefined } : undefined,
  };

  console.log(JSON.stringify(logEntry));
}

export const logger = {
  debug: (msg: string, data?: LogData) => log('DEBUG', msg, data),
  info: (msg: string, data?: LogData) => log('INFO', msg, data),
  warning: (msg: string, data?: LogData) => log('WARNING', msg, data),
  error: (msg: string, data?: LogData) => log('ERROR', msg, data),
};

API Client Integration

// lib/api-client.ts
import { logger } from './logger';
import { v4 as uuidv4 } from 'uuid';

export async function apiClient<T>(
  endpoint: string,
  options: RequestInit = {}
): Promise<T> {
  const requestId = `req_${uuidv4().slice(0, 8)}`;
  const startTime = Date.now();

  logger.info('API Request started', {
    request_id: requestId,
    method: options.method || 'GET',
    endpoint,
  });

  try {
    const response = await fetch(`/api${endpoint}`, {
      ...options,
      headers: {
        'Content-Type': 'application/json',
        'X-Request-ID': requestId,
        ...options.headers,
      },
    });

    const duration = Date.now() - startTime;
    const data = await response.json();

    // Log 200 OK too!
    logger.info('API Request completed', {
      request_id: requestId,
      status: response.status,
      duration_ms: duration,
    });

    if (!response.ok) {
      logger.error('API Request failed', {
        request_id: requestId,
        status: response.status,
        error: data.error,
      });
      throw new ApiError(data.error);
    }

    return data;
  } catch (error) {
    logger.error('API Request error', {
      request_id: requestId,
      error: error instanceof Error ? error.message : 'Unknown error',
    });
    throw error;
  }
}

Nginx JSON Logging

nginx.conf Configuration

http {
    log_format json_combined escape=json '{'
        '"timestamp":"$time_iso8601",'
        '"level":"INFO",'
        '"service":"nginx",'
        '"request_id":"$http_x_request_id",'
        '"message":"HTTP Request",'
        '"data":{'
            '"remote_addr":"$remote_addr",'
            '"method":"$request_method",'
            '"uri":"$request_uri",'
            '"status":$status,'
            '"body_bytes_sent":$body_bytes_sent,'
            '"request_time":$request_time,'
            '"upstream_response_time":"$upstream_response_time",'
            '"http_referer":"$http_referer",'
            '"http_user_agent":"$http_user_agent"'
        '}'
    '}';

    access_log /var/log/nginx/access.log json_combined;
}

Docker-Based QA Workflow

docker-compose.yml Configuration

version: '3.8'
services:
  api:
    build: ./backend
    environment:
      - LOG_LEVEL=DEBUG
      - LOG_FORMAT=json
    logging:
      driver: json-file
      options:
        max-size: "10m"
        max-file: "3"

  web:
    build: ./frontend
    environment:
      - NODE_ENV=development
    depends_on:
      - api

  nginx:
    image: nginx:alpine
    volumes:
      - ./nginx/nginx.conf:/etc/nginx/nginx.conf
    ports:
      - "80:80"
    depends_on:
      - api
      - web

Real-time Log Monitoring

# Stream all service logs
docker compose logs -f

# Specific service only
docker compose logs -f api

# Filter errors only
docker compose logs -f | grep '"level":"ERROR"'

# Track specific Request ID
docker compose logs -f | grep 'req_abc123'

QA Automation Workflow

1. Start Environment

# Start development environment
docker compose up -d

# Start log monitoring (Claude Code monitors)
docker compose logs -f

2. Manual UX Testing

User tests actual features in browser:
1. Sign up attempt
2. Login attempt
3. Use core features
4. Test edge cases

3. Claude Code Log Analysis

Claude Code in real-time:
1. Monitor log stream
2. Detect error patterns
3. Detect abnormal response times
4. Track entire flow via Request ID
5. Auto-document issues

4. Issue Documentation

# QA Issue Report

## Issues Found

### ISSUE-001: Insufficient error handling on login failure
- **Request ID**: req_abc123
- **Severity**: Medium
- **Reproduction path**: Login → Wrong password
- **Log**:
  ```json
  {"level":"ERROR","message":"Login failed","data":{"error":"Invalid credentials"}}

Problem: Error message not user-friendly
Recommended fix: Add error code to message mapping


---

## Issue Detection Patterns

### 1. Error Detection
```json
{"level":"ERROR","message":"..."}

→ Report immediately

2. Slow Response Detection

{"data":{"duration_ms":3000}}

→ Warning when exceeding 1000ms

3. Consecutive Failure Detection

3+ consecutive failures on same endpoint

→ Report potential system issue

4. Abnormal Status Codes

{"data":{"status":500}}

→ Report 5xx errors immediately

Phase Integration

Phase	Zero Script QA Integration
Phase 4 (API)	API response logging verification
Phase 6 (UI)	Frontend logging verification
Phase 7 (Security)	Security event logging verification
Phase 8 (Review)	Log quality review
Phase 9 (Deployment)	Production log level configuration

Iterative Test Cycle Pattern

Based on bkamp.ai notification feature development:

Example: 8-Cycle Test Process

Cycle	Pass Rate	Bug Found	Fix Applied
1st	30%	DB schema mismatch	Schema migration
2nd	45%	NULL handling missing	Add null checks
3rd	55%	Routing error	Fix deeplinks
4th	65%	Type mismatch	Fix enum types
5th	70%	Calculation error	Fix count logic
6th	75%	Event missing	Add event triggers
7th	82%	Cache sync issue	Fix cache invalidation
8th	89%	Stable	Final polish

Cycle Workflow

┌─────────────────────────────────────────────────────────────┐
│                   Iterative Test Cycle                        │
├─────────────────────────────────────────────────────────────┤
│                                                             │
│  Cycle N:                                                   │
│  1. Run test script (E2E or manual)                         │
│  2. Claude monitors logs in real-time                       │
│  3. Record pass/fail results                                │
│  4. Claude identifies root cause of failures                │
│  5. Fix code immediately (hot reload)                       │
│  6. Document: Cycle N → Bug → Fix                           │
│                                                             │
│  Repeat until acceptable pass rate (>85%)                   │
│                                                             │
└─────────────────────────────────────────────────────────────┘

E2E Test Script Template

#!/bin/bash
# E2E Test Script Template

API_URL="http://localhost:8000"
TOKEN="your-test-token"

PASS_COUNT=0
FAIL_COUNT=0
SKIP_COUNT=0

GREEN='\033[0;32m'
RED='\033[0;31m'
YELLOW='\033[0;33m'
NC='\033[0m'

test_feature_action() {
    echo -n "Testing: Feature action... "

    response=$(curl -s -X POST "$API_URL/api/v1/feature/action" \
        -H "Authorization: Bearer $TOKEN" \
        -H "Content-Type: application/json" \
        -d '{"param": "value"}')

    if [[ "$response" == *"expected_result"* ]]; then
        echo -e "${GREEN}✅ PASS${NC}"
        ((PASS_COUNT++))
    else
        echo -e "${RED}❌ FAIL${NC}"
        echo "Response: $response"
        ((FAIL_COUNT++))
    fi
}

# Run all tests
test_feature_action
# ... more tests

# Summary
echo ""
echo "═══════════════════════════════════════"
echo "Test Results:"
echo -e "  ${GREEN}✅ PASS: $PASS_COUNT${NC}"
echo -e "  ${RED}❌ FAIL: $FAIL_COUNT${NC}"
echo -e "  ${YELLOW}⏭️  SKIP: $SKIP_COUNT${NC}"
echo "═══════════════════════════════════════"

Test Cycle Documentation Template

# Feature Test Results - Cycle N

## Summary
- **Date**: YYYY-MM-DD
- **Feature**: {feature name}
- **Pass Rate**: N%
- **Tests**: X passed / Y total

## Results

| Test Case | Status | Notes |
|-----------|--------|-------|
| Test 1 | ✅ | |
| Test 2 | ❌ | {error description} |
| Test 3 | ⏭️ | {skip reason} |

## Bugs Found

### BUG-001: {Title}
- **Root Cause**: {description}
- **Fix**: {what was changed}
- **Files**: `path/to/file.py:123`

## Next Cycle Plan
- {what to test next}

Checklist

Logging Infrastructure

JSON log format applied
Request ID generation and propagation
Log level settings per environment
Docker logging configuration

Backend Logging

Logging middleware implemented
All API calls logged (including 200 OK)
Business logic logging
Detailed error logging

Frontend Logging

Logger module implemented
API client integration
Error boundary logging

QA Workflow

Docker Compose configured
Real-time monitoring ready
Issue documentation template ready

Auto-Apply Rules

When Building Logging Infrastructure

When implementing API/Backend:

Suggest logging middleware creation
Suggest JSON format logger setup
Add Request ID generation/propagation logic

When implementing Frontend:

Suggest Logger module creation
Suggest logging integration with API client
Suggest including Request ID header

When Performing QA

On test request:

Guide to run docker compose logs -f
Request manual UX testing from user
Real-time log monitoring
Document issues immediately when detected
Provide fix suggestions

Issue Detection Thresholds

Severity	Condition	Action
Critical	`level: ERROR` or `status: 5xx`	Immediate report
Critical	`duration_ms > 3000`	Immediate report
Critical	3+ consecutive failures	Immediate report
Warning	`status: 401, 403`	Warning report
Warning	`duration_ms > 1000`	Warning report
Info	Missing log fields	Note for improvement
Info	Request ID not propagated	Note for improvement

Required Logging Locations

Backend (FastAPI/Express)

✅ Request start (method, path, params)
✅ Request complete (status, duration_ms)
✅ Major business logic steps
✅ Detailed info on errors
✅ Before/after external API calls
✅ DB queries (in development)

Frontend (Next.js/React)

✅ API call start
✅ API response received (status, duration)
✅ Detailed info on errors
✅ Important user actions

zero-script-qa