Files
iris/tests/determinism.rs
T
iris-aiandClaude Opus 5 691e3eb23c Rename rest to leftover
The length kind that asks for a part of what is left once the fixed
lengths are taken is called leftover: Len::leftover(2), Len::LEFTOVER,
Size::LEFTOVER, Len::leftover the field, and apply_leftover. It says
what it is where "rest" reads as "the remainder of the list" as often as
"the remaining space", and every agent who has touched this has reached
for a third word for it.

Locals called rest that meant a region or a widget are renamed with it,
since the word now names something else.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-09-15 14:22:52 -04:00

102 lines
3.6 KiB
Rust

//! A measurement that decides control flow.
//!
//! Comparing boxes catches a widget that moved. It does not catch a widget
//! that measured a child, believed a different answer from the one a cold
//! start would give, and took the other branch -- which is the same defect
//! arriving somewhere it cannot be ignored. A widget here branches on what it
//! measured, so a disagreement shows up as a different tree.
use iris::harness::Harness;
use iris::prelude::*;
/// Measures `probe` across `axis` and draws one of two children on the
/// answer. Its own configuration never changes, so which child is drawn is a
/// property of the layout alone.
struct BranchesOnMeasurement {
probe: StrongWidget,
wide: StrongWidget,
narrow: StrongWidget,
threshold: f32,
}
impl Widget for BranchesOnMeasurement {
fn draw(&mut self, painter: &mut Painter) -> Size {
let mut top = UiRegion::FULL;
top.y.end = top.y.start.offset(40.0);
let measured = painter.place(&self.probe, top).len(Axis::X);
let px = measured.apply_leftover().to_px(painter.px_len(Axis::X));
let mut below = UiRegion::FULL;
below.y.start = below.y.start.offset(40.0);
match px > self.threshold {
true => painter.place(&self.wide, below),
false => painter.place(&self.narrow, below),
};
Size::LEFTOVER
}
}
fn plant(h: &mut Harness, threshold: f32) -> (WidgetId, WidgetId) {
let words = "the quick brown fox jumps over the lazy dog and keeps running";
let probe = wtext(words).size(16).wrap(true).add(&mut h.rsc);
let wide = rect(Color::RED).add(&mut h.rsc);
let narrow = rect(Color::BLUE).add(&mut h.rsc);
let branch = BranchesOnMeasurement {
probe: probe.add_strong(&mut h.rsc),
wide: wide.add_strong(&mut h.rsc),
narrow: narrow.add_strong(&mut h.rsc),
threshold,
}
.add(&mut h.rsc);
let side = rect(Color::GREEN).width(120).add(&mut h.rsc);
h.set_root((side, branch).span(Dir::RIGHT));
(wide.id(), narrow.id())
}
/// Which of the two branches drew, as a pair a test can compare.
fn taken(h: &Harness, wide: WidgetId, narrow: WidgetId) -> (bool, bool) {
(h.region(&wide).is_some(), h.region(&narrow).is_some())
}
#[test]
fn a_branch_taken_on_a_measurement_holds_across_repaints() {
for threshold in [0.0, 200.0, 400.0, 600.0, 779.0, 780.0, 781.0, 2000.0] {
let mut h = Harness::new((900, 600));
let (wide, narrow) = plant(&mut h, threshold);
let first = taken(&h, wide, narrow);
assert_ne!(first, (false, false), "threshold {threshold}: neither drew");
for frame in 0..4 {
h.rsc.widgets_mut().get_dyn_mut(wide);
h.rsc.widgets_mut().get_dyn_mut(narrow);
h.frame();
assert_eq!(
taken(&h, wide, narrow),
first,
"threshold {threshold}, repaint {frame}: the branch moved when nothing did"
);
}
}
}
#[test]
fn a_branch_taken_on_a_measurement_is_the_one_a_cold_start_takes() {
for threshold in [0.0, 200.0, 400.0, 600.0, 779.0, 780.0, 781.0, 2000.0] {
let mut warm = Harness::new((900, 600));
let (wide, narrow) = plant(&mut warm, threshold);
warm.resize((640, 480));
warm.frame();
warm.rsc.widgets_mut().get_dyn_mut(wide);
warm.frame();
let mut cold = Harness::new((640, 480));
let (cwide, cnarrow) = plant(&mut cold, threshold);
assert_eq!(
taken(&warm, wide, narrow),
taken(&cold, cwide, cnarrow),
"threshold {threshold}: warm and cold took different branches"
);
}
}