Python for Software Testers

List vs tuple?

Lists are mutable, tuples are immutable. Tuples are hashable and slightly faster — used for fixed records.

What are pytest fixtures?

Reusable setup/teardown functions injected into tests by name; scopes (function, class, module, session) control lifetime.

What is @pytest.mark.parametrize?

Runs a single test against multiple input sets, replacing boilerplate loops with named cases in reports.

Mutable default arguments — what's the trap?

Default values are evaluated once; using [] or {} as defaults leaks state across calls. Use None and create inside the function.

What is a generator?

A function with yield that produces values lazily — memory-efficient for large sequences.

Explain decorators.

Higher-order functions that wrap another function to extend behaviour (logging, retries, auth) without modifying it.

How do you do API tests in Python?

Use requests for HTTP, pytest as the runner, pydantic or jsonschema for validation, and fixtures for setup/teardown.

asyncio vs threads?

asyncio for IO-bound concurrency on a single thread (one event loop); threads for IO-bound with blocking libs; multiprocessing for CPU-bound work.

How do you manage dependencies?

Virtual environments (venv) plus pip-tools, Poetry, or uv; pin versions in a lockfile.

How do you structure a Python test project?

tests/ folder, conftest.py for shared fixtures, src/ layout for code, pyproject.toml for tooling, and a Makefile or task runner for CI commands.