max / quasi

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1	//! A guard inside a loop body, derived and filled.
2	//!
3	//! The regression test for a derivation bug rather than for a feature, and it
4	//! is here because the shape is ordinary: a strip of figures where each may or
5	//! may not report a change is what every dashboard in this tree draws.
6	//!
7	//! `grown` converts the placement it measures in the two-row render into the
8	//! body's own place in the one-row render, and it was subtracting a body length
9	//! from both ends of the window. The earliest placement does not move under
10	//! that conversion -- it is already the body's place -- so the window collapsed
11	//! to a point, and `placed` had nowhere to slide the span when the prefix scan
12	//! ran a byte past the body. `</div>` and `<div class="figure"` share their
13	//! `<`, which is all it takes. The loop then sat one byte off its own body,
14	//! overlapped the guard inside it, and `build` refused the screen as a
15	//! structure that is not a tree.
16	//!
17	//! Found on MNW's `/dashboard/tabs/analytics`, whose stats strip is three
18	//! guarded figures in a loop, one per tone a delta can carry.
19
20	// The fixture data below is built by this module's tests and by nothing else:
21	// the bench itself measures the shapes, not the rows behind them.
22	#![allow(dead_code)]
23	use quasi_declare::declare;
24	use quasi_router::screen::Figure;
25
26	pub(crate) struct Card {
27	pub value: String,
28	pub label: String,
29	pub delta: Option<String>,
30	}
31
32	pub(crate) fn cards(n: usize, with_delta: bool) -> Vec<Card> {
33	(0..n)
34	.map(\|i\| Card {
35	value: format!("{i}00"),
36	label: format!("Card {i}"),
37	delta: with_delta.then(\|\| format!("+{i}%")),
38	})
39	.collect()
40	}
41
42	fn delta(card: &Card) -> &str {
43	card.delta.as_deref().unwrap_or_default()
44	}
45
46	declare! {
47	/// A strip of figures, each of which may report a change.
48	#[staged]
49	pub(crate) shape strip(cards: &[Card]) -> Node;
50
51	stats [] {
52	for card in cards.iter() {
53	figure Figure::new(card.value.clone(), card.label.clone())
54	.change(delta(card))
55	unless card.delta.is_none();
56	}
57	}
58	}
59
60	#[cfg(test)]
61	mod tests {
62	use super::*;
63	use quasi_http::Serves as _;
64	use quasi_router::stage::Residual;
65	use quasi_webview::Webview;
66
67	fn residual() -> Residual {
68	quasi_webview::stage::derive(&Webview::new(), strip_staged)
69	}
70
71	#[test]
72	fn probe_residual() {
73	let residual = residual();
74	eprintln!("{:#?}", residual.ops());
75	}
76
77	#[test]
78	fn a_guard_inside_a_loop_body_derives() {
79	let webview = Webview::new();
80	let residual = residual();
81	for n in [0, 1, 3] {
82	for with in [false, true] {
83	let cards = cards(n, with);
84	assert_eq!(
85	webview.fragment(&strip(&cards)),
86	strip_serve(&residual, &cards),
87	"{n} cards, delta {with}"
88	);
89	}
90	}
91	}
92	}
93