How is backend service functionality tested without using a user interface?

Checking a backend service without using a user interface is usually done through API testing or monitoring.

Main approaches:

• Sending HTTP requests (GET, POST, etc.) to the service API and checking responses (status code, response body).
• Using tools for automated API testing, such as Postman, SoapUI, or writing scripts in programming languages.
• Monitoring the service status using health-check endpoints that return the operational status.

Example of a check using Python and the requests library:

import requests
response = requests.get('https://example.com/api/health')
if response.status_code == 200:
    print('Service is operational')
else:
    print('Problems with the service')