FrontendHaltTesting·Intermediate·Conceptual·1 min read
Why can testing with real timers make a debounce test slow across a large suite?
Short interview answer
Each test would need to actually wait out the real debounce delay, and those delays accumulate across many tests; fake timers let the same assertions run in milliseconds regardless of the configured delay.
Key takeaway
Explain the underlying mental model clearly, then support it with a concrete example and its trade-offs.