Testing Telegram Username Pipelines: A Contract-First Approach with Fixtures

Description and use

Define a contract and use local fixtures to test CSV parsing of Telegram Username Checker results, ensuring graceful handling of empty avatar_url and account statuses.

Problem

Integrations using the Telegram Username Checker API must robustly handle asynchronous result files where fields like avatar_url may be empty, risking runtime errors if not accounted for.

Outcome

A robust, contract-first parsing workflow that prevents runtime errors caused by missing avatar_url fields, validated through local fixtures and unit tests.

Workflow

• Define expected schema for result file (username, activated, avatar_url).
• Create local test fixture test_results.csv simulating API output with varied avatar_url states.
• Implement parser logic that treats empty avatar_url as None.
• Write unit tests covering positive, empty, and inactive account cases.
• Validate parser against fixture before integrating with live API.
• Poll task status via https://api.numberchecker.ai/v1/gettasks and download result only when status is exported.
• Integrate parser into production pipeline.

Evidence

By adopting a contract-first approach using local fixtures, you can ensure your downstream logic is resilient before you ever send a production request to https://api.numberchecker.ai/v1/tasks.

Source

The avatar_url field will be empty for accounts without a public photo.

Source