Testing Strategy and Error Handling Questions

Combines broader testing strategy for systems with a focus on error handling, resilience, and user experience when failures occur. Topics include designing a testing strategy that covers unit tests, integration tests, end to end tests and exploratory testing, applying the testing pyramid, defining error boundaries and recovery paths, graceful degradation and fallback strategies, user feedback and error messaging, fault injection and resilience testing, logging and observability to detect and reproduce errors, and validating error handling behavior across environments and edge cases.

EasyTechnical

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Write a small JavaScript function safeParseJSON(jsonString) that returns an object {success: boolean, value: any, error: string|null}. It must not throw, must handle invalid JSON gracefully, and must not allow prototype pollution (i.e., avoid assigning to __proto__ or constructor). Also write one example unit test in Jest for an invalid input.

EasyTechnical

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Define mocks, stubs, fakes, and spies. For each, give a concrete example in your preferred language and explain when you'd prefer that test double over a real dependency. Also explain one danger of overusing mocks in unit tests.

EasyTechnical

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What is a flaky test? Give three common root causes of flakiness in CI, and for each cause describe one practical mitigation you would implement. Include how you'd detect flakiness programmatically over time.

EasyTechnical

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Explain the testing pyramid concept and its practical implications for a typical web service. Describe what kinds of tests belong at each level (unit, integration, end-to-end), the expected ratio of tests, and one situation where you might intentionally depart from the pyramid.

MediumTechnical

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Implement a React ErrorBoundary component that logs errors to a provided logger and displays a localized fallback UI. Then write a React Testing Library test that asserts the logger was called and fallback text is rendered when a child component throws during render.

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