[Part 7]File I/O and Data Persistence in TypeScript for QA Automation

Introduction

Handling files and data persistence is crucial in automation testing for storing and retrieving test results. This module covers reading and writing files, working with CSV and JSON data, and automating file operations using Node.js with TypeScript.

---

Lesson 1: Reading and Writing Files using Node.js fs Module

Concept:
The fs module in Node.js enables file system interactions for handling test configurations, logs, and results.

Key Topics:

• fs Module Basics: Performing file operations.
• Reading Files: Loading configuration and test data.
• Writing Files: Storing test results.
• File Manipulation: Appending, renaming, and deleting files.

Example:

import * as fs from 'fs';

// Writing to a file
fs.writeFileSync('testResults.txt', 'Login Test: Passed');

// Reading from a file
const data = fs.readFileSync('testResults.txt', 'utf8');
console.log(data);

Pro Tip: Always handle file read/write operations asynchronously to avoid blocking execution.

---

Lesson 2: Working with CSV Files in TypeScript

Concept:
CSV files are widely used in test automation for storing test data and results.

Key Topics:

• Reading CSV Data: Extracting test case inputs.
• Writing CSV Files: Storing automation results.
• Using CSV Libraries: Implementing csv-parser or fast-csv.
• Data-Driven Testing: Using CSV for multiple test scenarios.

Example:

import * as fs from 'fs';
import * as csv from 'csv-parser';

fs.createReadStream('testData.csv')
  .pipe(csv())
  .on('data', (row) => console.log(row))
  .on('end', () => console.log('CSV File Processing Completed'));

Pro Tip: Use CSV files for data-driven test execution to improve efficiency.

---

Lesson 3: Parsing JSON Data in TypeScript for API Testing

Concept:
JSON is commonly used for API responses and test configurations in automation.

Key Topics:

• JSON Structure: Understanding JSON format.
• Parsing JSON: Converting JSON strings to TypeScript objects.
• Stringifying JSON: Writing JSON data to files.
• Using JSON for API Testing: Handling request and response validation.

Example:

let testData = '{ "testName": "Login", "status": "Passed" }';
let parsedData = JSON.parse(testData);
console.log(parsedData.testName);

let jsonString = JSON.stringify(parsedData, null, 2);
console.log(jsonString);

Pro Tip: Use TypeScript interfaces for strong typing in JSON data processing.

---

Lesson 4: Automating File System Operations in TypeScript

Concept:
File system automation helps manage logs, backups, and test results effectively.

Key Topics:

• Creating and Managing Directories: Handling test storage folders.
• File Copying: Automating test data backups.
• Monitoring File Changes: Detecting modifications in test logs.
• Deleting Files: Cleaning up temporary files.

Example:

import * as fs from 'fs';

// Creating a new directory
if (!fs.existsSync('logs')) {
    fs.mkdirSync('logs');
}

// Watching a file for changes
fs.watch('testResults.txt', (event, filename) => {
    console.log(`File ${filename} was modified: ${event}`);
});

Pro Tip: Use file watchers to trigger automation workflows when logs update.

---

Conclusion

This module provided insights into TypeScript’s file handling capabilities for test automation, enabling better test data management and logging.

Key Takeaways:

• The fs module allows efficient reading and writing of files.
• CSV files simplify data-driven test execution.
• JSON is essential for handling API test data.
• Automating file system operations improves test reporting and log management.

What’s Next?
In the next module, we will explore Introduction to TypeScript for Playwright – Preparation for UI Automation, where we will cover setting up Playwright, interacting with web elements, and transitioning to advanced UI automation strategies.

Visit us at Testamplify | X | Instagram | LinkedIn