pub const STEP_DELTA: Duration;Expand description
Fixed per-frame delta TestHarness::step hands to App::update.
Headless tests have no wall clock; this exists only so Frame::delta-driven code (tweens,
FrameClock) advances instead of stalling. 16ms is one frame at
~60fps; the value is otherwise arbitrary, but it is load-bearing for any test that counts steps
to reach an animation state: a duration-D animation finishes in ceil(D / 16ms) steps, so
changing this shifts those step counts.