SeniorCI/CD & DevOps for QA
How do you implement feature flags and how do they affect testing?
- feature flags
- canary releases
- test strategy
Answer it first, then compare. Nothing here is saved or scored.
Model answer
Feature flags allow toggling features without deployment (tools: LaunchDarkly, Unleash, or simple config). Testing implications: (1) Test matrix expands, each flag combination is a potential state. (2) Focus on critical combinations, not all permutations. (3) Test flag default state AND enabled state. (4) Test flag transitions - what happens when a flag is toggled in production? (5) Clean up old flags - untested dead code paths. (6) Use flags for canary releases - roll out to 5% of users, monitor, then expand. QA should be involved in flag rollout plans.
What interviewers listen for
- Pipeline shapeYou design stages by failure cost and runtime budget, not by tool feature lists.
- Parallelisation craftYou can shard a real suite and explain the state-isolation choices you made.
- Quality gatesYou know which checks block merge, which warn, and why those defaults are correct.
- Shift-left fluencyYou talk about ownership transfer, not just earlier execution.