Update README.md to enhance project documentation and provide detailed instructions for API contract tests

Author: AminaSaoudi

README.md

@@ -1 +1,71 @@
-# JSONPlaceholder-API-Tests
+# JSONPlaceholder API Contract Tests
+
+This repository contains automated **API contract and health tests** for the public JSONPlaceholder API using Postman.  
+The goal is to ensure response structure, data types, and status codes remain consistent with the documented API behavior.
+
+---
+
+## 🚀 Overview
+
+This project validates:
+
+- HTTP status codes  
+- Response times  
+- JSON schema/contract for posts  
+- Handling of path parameters  
+- Stability of the `/posts` resources  
+
+Tests run automatically using:
+
+- **Postman**
+- **Newman**
+- **GitHub Actions CI pipeline**
+
+---
+
+## 📁 Project Structure
+
+```
+/postman/
+  ├── JSONPlaceholder API Contract Tests.postman_collection.json
+  └── Development Environment.json
+.github/workflows/
+  └── api-tests.yml
+```
+
+---
+
+## 🧪 How to Run Locally
+
+### 1. Install Newman
+
+```bash
+npm install -g newman
+```
+
+### 2. Run the Collection
+
+```bash
+newman run "postman/JSONPlaceholder API Contract Tests.postman_collection.json" \
+  -e "postman/Development Environment.json"
+```
+
+### 3. Run with HTML Report (Optional)
+
+```bash
+newman run "postman/JSONPlaceholder API Contract Tests.postman_collection.json" \
+  -e "postman/Development Environment.json" \
+  -r htmlextra
+```
+
+---
+
+## 🌐 API Under Test
+
+All tests run against:
+
+```
+https://jsonplaceholder.typicode.com
+```
+
+The base URL is configured via the `baseUrl` environment variable in the environment file.