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Testability and Testing Practices Questions

Emphasizes designing code for testability and applying disciplined testing practices to ensure correctness and reduce regressions. Topics include writing modular code with clear seams for injection and mocking, unit tests and integration tests, test driven development, use of test doubles and mocking frameworks, distinguishing meaningful test coverage from superficial metrics, test independence and isolation, organizing and naming tests, test data management, reducing flakiness and enabling reliable parallel execution, scaling test frameworks and reporting, and integrating tests into continuous integration pipelines. Interviewers will probe how candidates make code testable, design meaningful test cases for edge conditions, and automate testing in the delivery flow.

MediumTechnical
0 practiced
Design a load testing scenario to validate that a service meets an SLO of p99 latency <200ms under 5k RPS. Describe traffic generation, realistic data shaping, ramp-up and steady-state phases, how to surface graceful degradation, and how to interpret results to accept/reject a build.
HardTechnical
0 practiced
Explain how you would ensure that on-call runbooks and diagnostics are testable and that automated tests validate runbook effectiveness. Provide concrete examples of tests that execute runbook steps in a sandbox and how to keep those tests up to date as systems change.
EasyTechnical
0 practiced
Explain the concept of test gating in CI/CD and describe trade-offs for SREs between blocking on all tests within a PR versus using a gate that allows merges with deferred tests. How would you decide which tests to gate and which to run asynchronously?
MediumTechnical
0 practiced
You want to enable reliable parallel execution across thousands of tests that currently share a single Redis instance. Propose strategies for isolation such as namespacing, ephemeral instances, or containerized Redis, and explain how to prevent resource contention and ensure deterministic behavior.
MediumSystem Design
0 practiced
Design a CI pipeline for a microservice that runs fast unit tests on PRs, parallel integration tests in ephemeral namespaces on merge, and nightly full e2e tests. Include artifact storage, test caching, secrets handling, ephemeral cluster lifecycle, and concurrency limits for a fleet of 200 services.

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