test: add unit and integration tests for backend APIs and risk calculation

[Suhaskumard]

Add Comprehensive Backend Testing Suite and Risk Logic Refactoring

This PR introduces a comprehensive backend testing suite for Climate-Shield and refactors the weather risk calculation logic into a dedicated module to improve maintainability, testability, and code organization.

Closes #182

Type of Change

☑️ Feature
☑️ Backend
☑️ Testing
☑️ Refactoring
☑️ Documentation

Changes Made

• Refactored weather risk calculation logic from alertsystem.py into a dedicated risk_calculator.py module

• Improved separation of concerns by isolating business logic from API routes

• Added centralized risk calculation utilities for:

  • Flood risk
  • Drought risk
  • Heat risk
  • Cyclone risk
  • Wildfire risk

• Added Pytest-based testing infrastructure

• Added reusable test fixtures through conftest.py

• Added unit tests for risk calculation algorithms

• Added integration tests for weather API endpoints

• Added integration tests for chatbot API endpoints

• Added validation for:

  • Normal weather conditions
  • Extreme heat scenarios
  • Extreme flood scenarios
  • Extreme drought scenarios
  • Extreme cold scenarios

• Added API error handling tests for:

  • Missing request fields
  • Missing API keys
  • Invalid locations
  • Timeout exceptions
  • Connection failures

• Added chatbot validation tests for:

  • Greetings
  • Knowledge base queries
  • Context-aware responses
  • Unknown topics
  • Empty payload handling

• Added implementation walkthrough documentation

Files Added

File	Purpose
backend/risk_calculator.py	Centralized weather risk calculation logic
backend/conftest.py	Shared Pytest fixtures and mocks
backend/test_risk_calculator.py	Unit tests for risk calculation algorithms
backend/test_weather_api.py	Integration tests for weather API endpoints
backend/test_chatbot_api.py	Integration tests for chatbot API endpoints
walkthrough.md	Testing suite implementation guide

Files Modified

File	Purpose
backend/alertsystem.py	Updated to use extracted risk calculation module
task.md	Updated implementation tracking and completion notes

How Has This Been Tested?

• Verified risk score calculations under normal weather conditions
• Verified extreme heat risk calculations
• Verified extreme flood risk calculations
• Verified extreme drought risk calculations
• Verified extreme cold weather handling
• Verified risk values are properly bounded and validated
• Verified chatbot endpoint responses for valid and invalid inputs
• Verified chatbot fallback behavior for unsupported queries
• Verified weather endpoint validation logic
• Verified API behavior when OpenWeatherMap API key is missing
• Verified location-not-found handling
• Verified timeout exception handling
• Verified connection error handling
• Executed full backend test suite using Pytest

Test Results

============================= 22 passed in 0.11s =============================

Checklist

☑️ My code follows the existing code style of the project
☑️ I have performed a self-review of my own code
☑️ I have added/updated tests where necessary
☑️ All backend tests pass successfully
☑️ My changes do not introduce any new warnings or errors
☑️ I have linked the related issue

[Suhaskumard]

Hi @thetechguardians,
I have solved the issue. If there are any changes, kindly let me know