Python + Pytest

Explain lazy iterators because pytest fixtures use yield for teardown.

Asked 'What is a generator / yield? Generator vs list — memory?' / 'Why does a fixture use yield?'

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Explain Python's object model to avoid the classic bugs interviewers plant.

Asked 'What does def f(a, b=[]) do across calls?' / 'is vs ==?' / 'deep vs shallow copy?'

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Use special methods and method types correctly and explain the difference.

Asked '@staticmethod vs @classmethod vs instance method?' / 'What is __repr__ vs __str__?' / 'Write a class usable in a with-block.'

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Write idiomatic Python fluently under time pressure.

Asked Expected fluency baked into every live coding task; 'rewrite this loop as a comprehension'

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Reason about failure paths and design clean error handling in tests/framework.

Asked 'Difference between else and finally?' / 'How do you make a custom exception?' / 'How do you assert an exception is raised?' (links to pytest.raises)

asked in interviews, not named in any job description

Load, parse and assert on structured test data.

Asked 'How do you read test data from a JSON/CSV?' / 'Parse this API response and assert a nested field.'

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Write a decorator live because pytest markers/fixtures ARE decorators.

Asked 'What is a decorator? Write one.' / 'Write a decorator that retries a flaky function N times.'

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Build resource setup/teardown safely — the pattern under fixtures and sessions.

Asked 'What is a context manager? Write one.' / 'Why use with over manual open/close?'

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Model a test-framework component as classes and defend the design choice live.

Asked 'Explain OOP with an example from your framework' / 'Design a class structure for a login-page test' / 'inheritance vs composition — when which?'

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Pick the right structure and state its Big-O cold, because coding rounds hinge on it.

Asked 'list vs tuple; when a set vs dict?' / most coding solutions are graded on choosing hashmap/set for O(n)

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Own API testing with requests — named in nearly every JD.

Asked 'Write an API test for this endpoint' / 'How do you structure an API client?' / 'How do you reuse auth across requests?'

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Explain why threads don't parallelize CPU work — justifies process-based test parallelism.

Asked 'What is the GIL? Does multithreading speed up CPU work?' / 'Why processes not threads for parallel tests?'

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Explain coroutines enough to test async APIs — deep asyncio NOT required.

Asked 'What is a coroutine / the event loop?' / 'How would you test an async API?'

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Use functions as values and flexible signatures — enables decorators/callbacks.

Asked 'What is a closure?' / 'What do *args and **kwargs do?' / 'sort by a custom key'

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Reach for the right stdlib helper — Counter/defaultdict shortcut many coding answers.

Asked Elegance signal in coding rounds ('solve first-non-repeating char' -> Counter); 'how do you memoize?'

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Annotate code and use dataclasses for clean test-data models.

Asked 'What do type hints do at runtime?' / 'When would you use a dataclass?'

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Share fixtures/config across the suite via conftest and explain resolution order.

Asked 'What is conftest.py? How are fixtures shared?' / 'What if two conftests define the same fixture?'

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Drive data-driven tests and know parametrize stacking / indirect via fixtures.

Asked 'How do you parametrize? Stack parametrize?' / 'What is indirect parametrization?'

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Tag and select tests; register custom markers to avoid warnings/errors.

Asked 'skip vs xfail?' / 'How do you run only smoke tests?' / 'How do you register a custom marker?'

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Assert idiomatically and test exceptions/floats correctly.

Asked 'How do you assert an exception is raised?' / 'Why plain assert not assertEqual?' / 'Compare floats in a test.'

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Design fixtures as the backbone of a framework and defend the choices.

Asked 'Explain fixtures' / 'fixture vs a parametrized test?' / 'How do fixtures compose?'

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Choose scope correctly and reason about it under parallelism — a senior signal.

Asked 'Fixture scopes — when session vs function?' / 'A session fixture leaks state between tests — fix it.'

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Isolate the unit under test — the genuine gap for QA-background SDETs.

Asked 'Mock vs MagicMock?' / 'return_value vs side_effect?' / 'How do you mock a method imported into another module?' (classic gotcha)

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Architect a maintainable framework and narrate the decisions — where SDET-2 offers are won.

Asked 'Design a framework to test a login page and list the test cases' / 'Walk me through a framework you built.'

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Speak to BDD/TDD workflow for shops that require it.

Asked 'Have you done BDD? How does Gherkin map to steps?' / 'Explain TDD.'

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Configure the runner project-wide the modern way.

Asked 'Where do you register markers / set default options?' / 'pyproject vs pytest.ini?'

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Drive the runner efficiently and debug fast in a live session.

Asked 'How do you rerun only failed tests?' / 'How do you find your slowest tests?'

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Assemble the standard plugin stack and know each one's failure mode.

Asked 'How do you run tests in parallel — and what breaks?' / 'How do you handle flaky tests?' / 'How do you gate on coverage?'

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Customize runner behavior via conftest hooks — separates SDET-2 from junior.

Asked 'How would you add a --env CLI flag?' / 'How do you attach a screenshot on test failure?'

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Test async code the modern (2025+) way after pytest-asyncio's breaking changes.

Asked 'How do you test an async function/endpoint?' / 'What changed in pytest-asyncio 1.0?'

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Package reusable pytest behavior — impressive, few candidates have it.

Asked 'Have you written a pytest plugin?' / 'How would you generate test cases dynamically from a data source?'

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Speak framework architecture in the design round — know 3-4, not all 23 GoF.

Asked 'Which design patterns have you used in your framework?' / 'How do you keep test data building clean?'

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Justify clean framework design with named principles.

Asked 'Explain SOLID' / 'How do SOLID principles show up in your framework?'

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Assert API contract shape, not just individual fields — higher-signal API testing.

Asked 'How do you validate an API response beyond status code?' / 'How do you assert the response schema?'

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Debug fast in a live session and when triaging complex automation failures.

Asked 'How do you debug a failing/flaky test?' / live: 'this test fails, find out why'

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Recognize and apply the two highest-yield array/string patterns.

Asked 'Find all anagram start indices' (sliding window) / 'triplet summing to target' (two-pointer)

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Use LIFO/FIFO for the bracket/parsing family.

Asked 'Validate balanced brackets' / 'evaluate/parse this expression'

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Write clean recursion and binary search with correct base cases/bounds.

Asked 'Write factorial recursively, handle edge cases' / 'search in a sorted array in O(log n)'

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Handle basic pointer/node problems — the TOP of the useful DSA ceiling for this band.

Asked 'Invert a binary tree' / 'reverse a linked list' / 'is this linked list a palindrome without extra space'

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Solve the most common coding-round category cleanly and optimally.

Asked Live coding: 'return all start indices of pattern's anagrams' / 'first non-repeating character' / two-sum

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State and defend time/space complexity out loud — the 2025-2026 raised bar.

Asked 'What's the time and space complexity?' / 'Can you do better than O(n^2)?' / 'What's the trade-off?'

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