Case Studies & Practical Application Flashcards

A team inherits a legacy codebase with no tests. They want to add tests safely without inadvertently altering behavior. What is the recommended first step?

Answer: Write characterization tests to document current behavior before refactoring

Characterization tests capture the existing (possibly buggy) behavior of legacy code so that refactoring can proceed without inadvertently changing that behavior.

A QA team must test a black-box system that accepts a numeric rating from 1 to 5. Using equivalence partitioning, which set of test values is most efficient?

Answer: 0, 3, 6

Equivalence partitioning divides inputs into valid (1–5) and invalid (5) partitions; one representative from each—such as 0, 3, and 6—covers all partitions efficiently.

An automated test suite takes 4 hours to run and blocks the CI pipeline. The fastest way to reduce feedback time while maintaining coverage is:

Answer: Parallelize test execution across multiple agents

Parallelizing test execution distributes the workload across multiple machines or agents, reducing total wall-clock time while maintaining the same coverage.

A financial application crashes with a stack overflow error only after running for 72 hours in production. Which testing approach is designed to detect this class of defect?

Answer: Soak (endurance) testing

Soak testing runs the system under normal load for an extended period to uncover memory leaks, resource exhaustion, and other degradation issues that only appear over time.

A tester changes a condition in the source code from '>' to '>=' and reruns the test suite. All tests still pass. What does this indicate?

Answer: The test suite has insufficient mutation coverage for this condition

In mutation testing, a surviving mutant (one not killed by the test suite) indicates the tests do not adequately cover or assert the behavior affected by that specific code change.

A company is releasing a new payment feature and wants real users to test it before full rollout. They enable it for 5% of users and monitor error rates. This practice is called:

Answer: Canary release testing

A canary release gradually rolls out a change to a small subset of users, allowing teams to detect issues and roll back before full deployment.

After adding a new payment gateway, the team must verify that the entire purchase flow—from browsing to order confirmation email—still works correctly. This is best achieved through:

Answer: End-to-end testing of the full user journey

End-to-end testing validates complete user journeys across all integrated components, ensuring the entire flow works as a system.