How would you test DFS Cycle Detection (Directed Graph)?

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Quick interview answer

Test DFS Cycle Detection (Directed Graph) with unit checks for the happy path, integration tests for real I/O boundaries, and load/chaos checks so regressions show up before prod. Core idea: Mitigate first, then root-cause. Check symptoms against: Using two-color visited only (misses cross edges in undirected); forgetting disconnected components..

Detailed answer

Interview answer for testing DFS Cycle Detection (Directed Graph): 1) Unit: isolate the pure logic behind DFS Cycle Detection (Directed Graph) with deterministic fixtures. 2) Integration: exercise real timers/I/O/network boundaries the way production does. 3) Load & soak: prove the event path still meets SLOs under concurrency. 4) Failure injection: break dependencies and assert recovery/backpressure. Best practices to include: Loop all nodes as DFS roots; explain gray = active recursion path. Call out mistakes: Using two-color visited only (misses cross edges in undirected); forgetting disconnected components. Parent context: Mitigate first, then root-cause. Check symptoms against: Using two-color visited only (misses cross edges in undirected); forgetting disconnected components..

Full explanation

Interviewers want a test strategy, not “I would write tests.” Tie each layer back to how DFS Cycle Detection (Directed Graph) fails: correctness, latency, and starvation. Three-color DFS: white=unvisited, gray=in current stack, black=done. Back edge to gray node ⇒ cycle. Works for dependency graphs and course prerequisites.

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Parent context — DFS Cycle Detection (Directed Graph)

Mitigate first, then root-cause. Check symptoms against: Using two-color visited only (misses cross edges in undirected); forgetting disconnected components..

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