Condition-Based Waiting

Overview

Flaky tests often guess at timing with arbitrary delays. This creates race conditions where tests pass on fast machines but fail under load or in CI.

Core principle: Wait for the actual condition you care about, not a guess about how long it takes.

When to Use

Decision flow: Test uses setTimeout/sleep? → Testing actual timing behavior? → (yes: document WHY timeout needed) | (no: use condition-based waiting)

Use when: Arbitrary delays (setTimeout, sleep) | Flaky tests (pass sometimes, fail under load) | Timeouts in parallel runs | Async operation waits

Don't use when: Testing actual timing behavior (debounce, throttle) - document WHY if using arbitrary timeout

Core Pattern