obscura/crates/obscura-render/tests/layout_test.rs

//! Regression test: a Hacker-News-shaped nested `<table>` layout must come out
//! right using only the general engine (UA defaults + real CSS cascade), with
//! no per-site hardcoded selectors. This guards against reintroducing the
//! site-specific hacks that used to live in obscura-render for this exact markup.

use obscura_dom::tree_sink::parse_html;
use obscura_render::layout_dom;

const HN_HTML: &str = r##"
    <table border="0" cellpadding="0" cellspacing="0" width="85%" bgcolor="#f6f6ef">
        <tr>
            <td bgcolor="#ff6600">
                <table border="0" cellpadding="0" cellspacing="0" width="100%" style="padding:2px">
                    <tr>
                        <td style="width:18px;padding-right:4px"><a href="https://news.ycombinator.com"><img src="y18.svg" width="18" height="18"></a></td>
                        <td style="line-height:12pt; height:10px;"><span class="pagetop"><b class="hnname"><a href="news">Hacker News</a></b> <a href="newest">new</a> | <a href="front">past</a></span></td>
                        <td style="text-align:right;padding-right:4px;"><span class="pagetop"><a href="login?goto=news">login</a></span></td>
                    </tr>
                </table>
            </td>
        </tr>
        <tr>
            <td>
                <table border="0" cellpadding="0" cellspacing="0">
                    <tr class="athing submission" id="48761229">
                        <td align="right" valign="top" class="title"><span class="rank">24.</span></td>
                        <td valign="top" class="votelinks"><center><a id="up_48761229" href="vote?id=48761229"><div class="votearrow" title="upvote"></div></a></center></td>
                        <td class="title"><span class="titleline"><a href="https://www.zachtronics.com/exapunks/">Exapunks (2018)</a></span></td>
                    </tr>
                </table>
            </td>
        </tr>
    </table>
"##;

/// Top-left of the tightest laid-out element box whose text contains
/// `needle`. Text geometry is no longer a per-word list: a pure-text
/// container collapses to a single cosmic-text inline formatting context
/// (see `inline`), and even in the word-split path the wrapping `<a>`/`<span>`
/// are flattened into their block, so the smallest element rect enclosing the
/// text is the meaningful, mode-independent anchor. Picking the smallest-area
/// match skips the giant ancestor tables that also "contain" the text.
fn find_by_text(
    tree: &obscura_dom::tree::DomTree,
    layout: &obscura_render::DomLayout,
    needle: &str,
) -> Option<(f32, f32)> {
    let mut best: Option<(f32, obscura_render::Rect)> = None;
    for (id, rect) in &layout.rects {
        if tree.text_content(*id).contains(needle) {
            let area = rect.width * rect.height;
            if best.as_ref().map(|(a, _)| area < *a).unwrap_or(true) {
                best = Some((area, *rect));
            }
        }
    }
    best.map(|(_, r)| (r.x, r.y))
}

#[test]
fn hn_shaped_table_lays_out_without_site_hardcoding() {
    let tree = parse_html(HN_HTML);
    let layout = layout_dom(&tree, (1000.0, 1000.0));

    // Every element got a rect; the tree isn't just being dropped.
    assert!(layout.rects.len() > 10, "expected many laid-out elements, got {}", layout.rects.len());

    // "Hacker News" (a bold link in the top bar) sits above the first
    // headline row ("Exapunks (2018)"): normal top-to-bottom flow, not a
    // hardcoded absolute position.
    let (brand_x, brand_y) = find_by_text(&tree, &layout, "Hacker News").expect("brand text laid out");
    let (_, headline_y) = find_by_text(&tree, &layout, "Exapunks (2018)").expect("headline text laid out");
    assert!(
        headline_y > brand_y,
        "headline should be below the header bar: brand.y={} headline.y={}",
        brand_y,
        headline_y
    );

    // Within the header row, "login" (right-aligned cell) sits to the right
    // of "Hacker News" (left cell) — plain flex/table layout, not a magic
    // per-class x-offset.
    let (login_x, _) = find_by_text(&tree, &layout, "login").expect("login text laid out");
    assert!(
        login_x > brand_x,
        "login cell should be right of the brand: brand.x={} login.x={}",
        brand_x,
        login_x
    );
}

#[test]
fn relative_units_resolve_against_viewport_and_font_size() {
    // 50vw of a 1000px viewport = 500px; 10em at the default 16px = 160px.
    // Both were previously mis-resolved (vw kept as raw px, em hardcoded to 16
    // regardless of context), so this guards the deferred-resolution pass.
    let html = r##"<div style="width:50vw;height:10em"></div>"##;
    let tree = parse_html(html);
    let layout = layout_dom(&tree, (1000.0, 800.0));
    let hit = layout.rects.values().any(|r| (r.width - 500.0).abs() < 1.0 && (r.height - 160.0).abs() < 1.0);
    assert!(hit, "expected a 500x160 box from 50vw/10em, rects: {:?}", layout.rects.values().map(|r| (r.width, r.height)).collect::<Vec<_>>());
}

#[test]
fn percentage_padding_top_reserves_aspect_ratio_box() {
    // The responsive aspect-ratio trick: an empty box with padding-top:56.25%
    // inside a 1000px-wide block reserves a 16:9 area (~562px tall), the room a
    // `position:absolute; inset:0` media child fills. Percentage padding
    // resolves against the containing block WIDTH on every side, so the box
    // gains real height instead of collapsing to zero.
    let html = r##"<div style="width:1000px"><div style="padding-top:56.25%"></div></div>"##;
    let tree = parse_html(html);
    let layout = layout_dom(&tree, (1200.0, 800.0));
    let hit = layout
        .rects
        .values()
        .any(|r| (r.width - 1000.0).abs() < 1.0 && (r.height - 562.5).abs() < 2.0);
    assert!(
        hit,
        "expected a ~1000x562 aspect-ratio box from padding-top:56.25%, rects: {:?}",
        layout.rects.values().map(|r| (r.width, r.height)).collect::<Vec<_>>()
    );
}

#[test]
fn long_text_run_wraps_across_multiple_lines() {
    // A long single text node with no inline elements breaking it up must
    // wrap within a narrow container instead of overflowing on one line. The
    // container's height is the mode-independent proof: several wrapped lines
    // make it much taller than one line, whether text is shaped by cosmic-text
    // (paint) or split into word boxes (layout-only).
    let html = r##"<div style="width:100px">This sentence has plenty of words to wrap across several lines</div>"##;
    let tree = parse_html(html);
    let layout = layout_dom(&tree, (1000.0, 1000.0));

    // Tightest element enclosing the text: the 100px div itself.
    let mut div_rect: Option<obscura_render::Rect> = None;
    for (id, rect) in &layout.rects {
        if tree.text_content(*id).contains("several lines") {
            if div_rect.as_ref().map(|d| rect.width * rect.height < d.width * d.height).unwrap_or(true) {
                div_rect = Some(*rect);
            }
        }
    }
    let div_rect = div_rect.expect("text container laid out");
    assert!(div_rect.width <= 101.0, "container should hold its 100px width, got {}", div_rect.width);
    assert!(
        div_rect.height > 60.0,
        "text should wrap onto several lines in a 100px-wide box (tall container), got height {}",
        div_rect.height
    );
}