Software Testing and Assertions Questions

Core software testing and debugging practices, including designing tests that exercise normal, edge, boundary, and invalid inputs, writing clear and maintainable unit tests and integration tests, and applying debugging techniques to trace and fix defects. Candidates should demonstrate how to reason about correctness, create reproducible minimal failing examples, and verify solutions before marking them complete. This topic also covers writing effective assertions and verification statements within tests: choosing appropriate assertion methods, composing multiple assertions safely, producing descriptive assertion messages that aid debugging, and structuring tests for clarity and failure isolation. Familiarity with test design principles such as test case selection, test granularity, test data management, and test automation best practices is expected.

MediumTechnical

55 practiced

Write unit tests for a SQL query function using an in-memory SQLite database in Python. Include schema creation, sample data insertion, tests for expected rows, and edge cases such as no rows returned and duplicate keys. Use pytest fixtures to manage the DB lifecycle.

HardSystem Design

50 practiced

Design golden-file (snapshot) testing for outputs like HTML emails and generated PDFs. Cover strategies for stable diffs (normalizing timestamps/IDs), storage/versioning of golden files, human approval workflows for legitimate changes, CI automation for snapshot comparisons, and how to detect noise vs meaningful changes.

MediumTechnical

55 practiced

List common test anti-patterns such as over-mocking, fragile assertions, test-order dependence, expensive shared fixtures, and unclear assertions. For each anti-pattern describe why it harms quality and give concrete steps to remediate or prevent it during code review.

EasyTechnical

51 practiced

Describe the test pyramid and how it applies to a complex SaaS product. Explain recommended test distribution between unit, integration, and end-to-end tests, and discuss exceptions where you may intentionally deviate from the pyramid (for example, critical UI flows or external compliance requirements).

HardTechnical

97 practiced

For a C++ low-level module, design a test plan to validate memory safety and undefined behavior. Include unit tests with AddressSanitizer and UndefinedBehaviorSanitizer, fuzzing harnesses for public APIs, CI integration of sanitizers, and an example unit test that would trigger a common UB such as signed integer overflow or out-of-bounds access to validate the sanitizer catches it.

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