Overcoming Geo-Blocking: A TypeScript-Based Strategy for Testing Location-Restricted Features

#typescript #testing #geolocation

When it comes to testing geo-blocked features—such as region-specific content, access restrictions, or location-dependent functionalities—challenging constraints often stem from environmental limitations. As a Lead QA Engineer, I faced a scenario where the tests needed to simulate different geographic locations, but comprehensive documentation and ready-made tools were lacking. Leveraging TypeScript’s strong typing and flexible environment, I devised a structured approach to emulate geolocation data effectively.

Understanding the Challenge

Geo-restrictions are generally enforced through API calls, backend validations, or based on the client's geolocation API, which returns latitude and longitude. In our project, the main obstacle was the absence of explicit documentation or clear hooks into the geo-restriction logic. This meant that we had to infer or reverse-engineer the location constraints to create reliable tests.

Step 1: Analyze the Application’s Geolocation Pattern

First, identify how the application retrieves and processes location data. Common methods include:

Using the browser’s navigator.geolocation API.
An external IP-based geolocation API.
Custom headers or parameters in API requests.

By inspecting network logs and application code, I found that our system used a third-party IP geolocation service behind the scenes.

Step 2: Emulate Geolocation Data in Tests

Without formal documentation, the key was to mock the geolocation responses. In TypeScript, I created interfaces and mock functions:

interface GeoLocation {
  latitude: number;
  longitude: number;
  country: string;
}

function getMockGeoLocation(countryCode: string): GeoLocation {
  const geoData: { [key: string]: GeoLocation } = {
    US: { latitude: 37.7749, longitude: -122.4194, country: 'United States' },
    DE: { latitude: 52.5200, longitude: 13.4050, country: 'Germany' },
    IN: { latitude: 20.5937, longitude: 78.9629, country: 'India' },
  };
  return geoData[countryCode] || geoData['US'];
}

This function allows dynamic generation of geolocation data based on the test case.

Step 3: Override Location APIs During Testing

Next, intercept and mock real calls to the geolocation API or IP-based services.

// Example for navigator.geolocation
jest.spyOn(navigator, 'geolocation', 'getCurrentPosition').mockImplementation((success) => {
  const mockLocation = getMockGeoLocation('DE');
  success({ coords: { latitude: mockLocation.latitude, longitude: mockLocation.longitude } } as Position);
});

For server-side calls, mock the HTTP client:

import axios from 'axios';
jest.mock('axios');

const mockedAxios = axios as jest.Mocked<typeof axios>;
mockedAxios.get.mockImplementation((url) => {
  if (url.includes('ipgeolocation')) {
    return Promise.resolve({ data: getMockGeoLocation('IN') });
  }
  return Promise.reject(new Error('Unknown API'));
});

Step 4: Validate Geo-Blocked Behavior

After mocking, execute the feature’s access check within your tests, asserting correct behavior:

test('User from Germany accesses region-restricted feature', async () => {
  // Mock geolocation to Germany
  jest.spyOn(navigator, 'geolocation', 'getCurrentPosition').mockImplementation(...);

  const result = await featureAccessCheck();
  expect(result).toBe('Access Granted');
});

This process ensured that the geo-restriction logic was thoroughly tested without relying on the real location or external dependencies.

Conclusion

By reverse-engineering the geolocation mechanism and utilizing TypeScript’s type safety and mocking capabilities, we can effectively simulate different geographic conditions. This method enhances test reliability and coverage for location-based features, vital for compliance and user experience.

Maintaining clear separation between test code and production logic—along with detailed comments—ensures that future team members understand the mocked environment. It's also essential to document the assumptions and mappings used for each region, as geographic restrictions can be complex and evolving.

Finally, always validate your geolocation mocks against real-world data periodically to ensure long-term reliability, especially when relying on third-party IP or geolocation APIs with shifting IP mappings.