beady-eye 0.13.0

//! The forest and the tail, drawn into a ratatui frame.
//!
//! One module for each thing drawn — a project's line, a bead's, the groups,
//! the foot, the tail — one for the bands they are drawn into, and one for
//! the colours they are drawn in. What is left here is the frame itself:
//! which kind of line each row is, and the few cells that more than one kind
//! draws with.

mod bands;
pub(in crate::view) mod bead;
mod foot;
mod groups;
mod project;
mod tail;
pub(crate) mod tone;

use std::collections::BTreeMap;

use chrono::{DateTime, Utc};
use ratatui::layout::Rect;
use ratatui::style::Style;
use ratatui::text::Span;
use ratatui::Frame;

use crate::app::Awaited;
use crate::model::types::PaneStatus;
use crate::view::fitted::{Fitted, GAP};
use crate::view::forest::Forest;
use crate::view::lines::{self, Content, Note, ProjectLine};
use crate::view::palette;
use crate::view::phrase;
use crate::view::row::{Cell, Layout, Widths, AGENT, WARNING};
use crate::view::{Freshness, Notice, Said};

pub use bands::{line_at, regions};
pub(crate) use bead::identity_widths;
pub use tail::{draw_tail, Band};

use bead::{bead_line, elided_run};
use foot::{notices, status_bar};
use groups::{group_line, item_line, scoped_line};
use project::{project_line, unread_line};

/// What every project line's freshness is drawn from: when each project was
/// last read, which projects have a read outstanding, and the instant this
/// frame is being drawn at.
///
/// Gathered at the frame rather than held on the lines. A read being asked
/// for and coming back changes what a project line says without changing the
/// snapshot under it, and the mark turns between two collections' worth of
/// events — so a line that carried its own answer would have to be flattened
/// again to say anything new.
pub(super) struct Reads<'a> {
    read_at: &'a BTreeMap<String, DateTime<Utc>>,
    /// Every read outstanding — the collection in flight and whatever is
    /// queued behind it — and when each was asked for. The instant is what
    /// tells a read that is getting somewhere from one that has stopped.
    collecting: &'a [Awaited],
    now: DateTime<Utc>,
}

impl<'a> Reads<'a> {
    pub(super) fn new(
        read_at: &'a BTreeMap<String, DateTime<Utc>>,
        collecting: &'a [Awaited],
        now: DateTime<Utc>,
    ) -> Self {
        Self {
            read_at,
            collecting,
            now,
        }
    }

    /// How fresh one project is.
    ///
    /// Whether a read of it is outstanding is asked with `Wanted::names`, of
    /// the very sequence the collector is served from, so the line and the
    /// collector agree by construction rather than by argument. How the last
    /// collection of it went comes off the line, because it changes only when
    /// the snapshot does.
    ///
    /// More than one outstanding read can name one project, and routinely
    /// does: a whole collection names every project, so one queued behind a
    /// single project — or with one queued behind it — names that project
    /// twice over. The reader's question is how long this project's rows have
    /// been on their way, so the answer is the earliest of them.
    fn of(&self, project: &ProjectLine) -> Option<Freshness> {
        Freshness::of(
            self.read_at.get(&project.project).copied(),
            self.collecting
                .iter()
                .filter(|awaited| awaited.wanted.names(&project.project))
                .min_by_key(|awaited| awaited.asked_at),
            project.every_root_read,
            self.now,
        )
    }
}

/// What the row at the foot of the screen is handed: what this run cannot
/// do, what the reader has just copied, and the keys.
///
/// `keys` arrives already named. What a key is called belongs with the
/// mapping that answers it, and this file has never known one.
pub struct Foot<'a> {
    pub standing: &'a [Notice],
    /// What the reader's last keystroke came to, until their next key or
    /// click.
    pub said: Option<&'a Said>,
    /// What the reader has typed into the search prompt, while one is up.
    pub prompt: Option<&'a str>,
    /// The row of keys and every shorter form of it the loop will stand
    /// behind, fullest first.
    pub keys: &'a [String],
}

/// Draw the forest and the foot, leaving the tail's band to whoever holds a
/// tail.
pub fn draw(
    frame: &mut Frame,
    area: Rect,
    forest: &Forest,
    layout: &Layout,
    collecting: &[Awaited],
    now: DateTime<Utc>,
    foot: Foot,
) {
    let bands = regions(area);
    let lines = forest.lines();
    let selected = forest.selected_line();
    let height = bands.forest.height as usize;
    let widths = lines.widths();
    let reads = Reads::new(&forest.snapshot().read_at, collecting, now);

    for (row, (at, line)) in lines.viewport(forest.from(), height).enumerate() {
        let drawn = fitted(line, widths, layout, &reads);
        let drawn = if at == selected {
            drawn.selected()
        } else {
            drawn
        };
        frame.render_widget(
            drawn,
            Rect {
                y: bands.forest.y + row as u16,
                height: 1,
                ..bands.forest
            },
        );
    }

    frame.render_widget(
        status_bar(
            &notices(forest.snapshot(), foot.standing),
            foot.said,
            foot.prompt,
            foot.keys,
            forest.spine(),
            bands.keys.width as usize,
        ),
        bands.keys,
    );
}

/// One line of the forest, whatever kind it is.
pub(super) fn fitted(
    line: &lines::Line,
    widths: &Widths,
    layout: &Layout,
    reads: &Reads,
) -> Fitted {
    match &line.content {
        Content::Project(project) => {
            project_line(project, &line.prefix, reads.of(project), reads.now)
        }
        Content::Unread(unread) => unread_line(unread, &line.prefix, widths.of(&Cell::Id)),
        Content::Bead(row) => bead_line(row, &line.prefix, widths, layout),
        Content::Elided { count, .. } => elided_run(&line.prefix, *count),
        Content::Note(note) => {
            let (said, style) = finding(*note);
            sentence(&line.prefix, said, style)
        }
        Content::Group(group) => group_line(&line.prefix, group),
        Content::Item(item) => item_line(&line.prefix, item),
        Content::Scoped { project } => scoped_line(&line.prefix, project),
    }
}

/// A line that is one sentence and nothing else.
pub(super) fn sentence(prefix: &str, said: String, style: Style) -> Fitted {
    Fitted::new(
        vec![Span::raw(prefix.to_string()), Span::styled(said, style)],
        Vec::new(),
        Vec::new(),
    )
}

/// A finding about the tree above, in `bdi`'s words for it, and what it is
/// said in.
///
/// An empty forest is the one note nothing went wrong in — the trackers
/// answered and there was no work — so it alone is drawn plain, the way
/// `group_line` draws the hidden trees.
fn finding(note: Note) -> (String, Style) {
    let said = match note {
        Note::Dangling(count) => phrase::dangling(count),
        Note::Cycle(count) => phrase::cycle(count),
        Note::NoRoots => return (phrase::no_roots().to_string(), palette::PLAIN),
    };
    (format!("{WARNING} {said}"), palette::ATTENTION)
}

/// How far along something is. A tree and one epic inside it ask the same
/// question of different scopes, so they answer it in the same words.
pub(super) fn done(closed: usize, total: usize) -> String {
    format!("{closed}/{total}")
}

/// Put a cell in a row's state block, beside the ones already there.
///
/// The gap belongs *between* the cells: two that abut read as one that names
/// neither, and a gap in front of the first is spent rather than seen,
/// because the block is set against the row's right edge and the padding
/// swallows it. Every state block on a row is built this way, so there is one
/// place to be right about it rather than one per kind of row.
pub(super) fn beside(state: &mut Vec<Span<'static>>, cell: Span<'static>) {
    if !state.is_empty() {
        state.push(Span::raw(" ".repeat(GAP)));
    }
    state.push(cell);
}

pub(super) fn pane_marker(pane: &str, status: &PaneStatus) -> String {
    format!("{AGENT} {pane} {}", phrase::pane_state(status))
}

/// The box-drawing a line hangs under. It says how the tree is shaped rather
/// than how a bead is going, so it is held at the terminal's default while the
/// row around it dims or brightens. `bd list` leaves its own tree prefix
/// undimmed on a closed row too.
pub(super) fn structure(prefix: &str) -> Span<'static> {
    Span::styled(prefix.to_string(), palette::STRUCTURE)
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::model::types::testing::key;
    use pretty_assertions::assert_eq;
    use ratatui::style::Color;
    use ratatui::style::Modifier;
    use std::collections::BTreeMap;
    use std::sync::Arc;

    use crate::app::Wanted;
    use crate::config::Scope;
    use crate::model::join::{AgentRef, BeadKey, JoinSource};
    use crate::model::snapshot::{
        a_provider, Counts, Filter, HiddenTree, LoosePane, Node, ProviderState, Snapshot,
        TrackerFailure, TrackerState, Tree,
    };
    use crate::model::tree::Link;
    use crate::model::types::{Edge, Status};
    use crate::view::forest::flatten;
    use crate::view::row::{self, Row};
    use crate::view::{Action, Motion};
    use chrono::{DateTime, TimeZone, Utc};

    pub(super) use crate::view::painted::Painted;
    pub(super) use crate::view::tests::{does_not_say, says};

    pub(super) const OPEN: &str = "▾ ";
    pub(super) const SHUT: &str = "▸ ";
    pub(super) const BRANCH: &str = "  ├── ";
    pub(super) const LAST: &str = "  └── ";

    /// A run of closed siblings, under whichever bead the test likes: the
    /// drawing says the count and nothing about the bead it hangs under.
    pub(super) fn elided(count: usize) -> Content {
        Content::Elided {
            count,
            under: lines::Place::root(BeadKey {
                project: "dunwich".into(),
                id: "dun-7".into(),
            }),
        }
    }

    /// One forest line, behind the box-drawing a flatten would have put in
    /// front of it.
    pub(super) fn under(prefix: &str, content: Content) -> lines::Line {
        lines::Line {
            prefix: prefix.into(),
            depth: 1,
            folded: None,
            place: None,
            content,
        }
    }

    pub(super) fn counts(
        closed: usize,
        total: usize,
        live_agents: usize,
        anomalies: usize,
    ) -> Counts {
        Counts {
            total,
            closed,
            live_agents,
            anomalies,
        }
    }

    pub(super) fn tree(project: &str, root: &str, title: &str, counts: Counts) -> Tree {
        Tree {
            project: project.into(),
            root: root.into(),
            title: title.into(),
            counts,
            tracker: TrackerState::Ok,
            beads: Vec::new(),
            children: Vec::new(),
            dangling: Vec::new(),
            cycles: Vec::new(),
        }
    }

    pub(super) fn node(id: &str, title: &str, status: Status) -> Node {
        Node {
            id: id.into(),
            title: title.into(),
            status,
            issue_type: "task".into(),
            priority: 2,
            ready: false,
            blocked_by: Vec::new(),
            started_at: None,
            closed_at: None,
            badges: Vec::new(),
            undrawn: Vec::new(),
            agent: None,
            anomalies: Vec::new(),
            description: String::new(),
            notes: String::new(),
            created_by: None,
            assignee: None,
            labels: Vec::new(),
            created_at: None,
            updated_at: None,
            parent: None,
            depends_on: Vec::new(),
            blocks: Vec::new(),
        }
    }

    pub(super) fn pane(pane: &str, status: PaneStatus) -> LoosePane {
        LoosePane {
            pane: key(pane),
            project: "summit-works".into(),
            cwd: "/tmp/bdi-ground/summit-works".into(),
            pane_status: status,
            display_agent: None,
            title: None,
            claim_refused: false,
        }
    }

    pub(super) fn row(node: &Node) -> Row {
        row::cells(node, Some("smt-4kd3p"), None, None)
    }

    /// A width table padding the id alone, as the default layout's forest
    /// answers.
    pub(super) fn ids(width: usize) -> Widths {
        Widths::from([(Cell::Id, width)])
    }

    /// A project whose roots all read, so its line is its name and its counts.
    pub(super) fn project(name: &str, counts: Counts) -> ProjectLine {
        ProjectLine {
            project: name.into(),
            counts,
            every_root_read: true,
        }
    }

    /// A pane with something on it, which is all most of these rows need to
    /// know about an agent.
    pub(super) fn a_pane() -> AgentRef {
        AgentRef {
            pane: key("wCM:p9"),
            pane_status: PaneStatus::Working,
            title: None,
            source: JoinSource::AgentPane,
        }
    }

    /// A key row shaped like the real one, without importing the loop's.
    pub(super) const A_KEY_ROW: &str = "Enter focus   a all   ? keys   ^R refresh   q quit";

    /// It as the foot takes it: one form, so it goes whole or not at all.
    pub(super) fn a_key_row() -> Vec<String> {
        vec![A_KEY_ROW.to_string()]
    }

    #[test]
    fn a_note_leaves_its_box_drawing_in_the_terminals_own_colour() {
        let painted = Painted::of(
            fitted(
                &under(LAST, Content::Note(Note::Dangling(2))),
                &ids(0),
                &Layout::default(),
                &at_rest(),
            ),
            96,
            1,
        )
        .row(0);

        assert_eq!(painted[0].said, LAST);
        assert_eq!(painted[0].style.fg, Some(Color::Reset));
        assert_eq!(painted[1].style.fg, palette::ATTENTION.fg);
    }

    /// Every other note is a fault and wears a warning. Nothing went wrong in
    /// a forest with no work left in it, and a warning over that reads as one
    /// — so it is drawn plain, in one colour the whole way across.
    #[test]
    fn the_line_for_an_empty_forest_is_drawn_in_the_terminals_own_colour() {
        let painted = Painted::of(
            fitted(
                &under("", Content::Note(Note::NoRoots)),
                &ids(0),
                &Layout::default(),
                &at_rest(),
            ),
            96,
            1,
        )
        .row(0);

        assert_eq!(painted.len(), 1, "{painted:?}");
        assert_eq!(painted[0].style.fg, Some(Color::Reset));
        assert!(!painted[0].said.contains(WARNING), "{painted:?}");
    }

    // ---- the whole frame -------------------------------------------------

    pub(super) fn snapshot(
        trees: Vec<Tree>,
        unattributed: Vec<LoosePane>,
        agents: ProviderState,
    ) -> Snapshot {
        // The projects a real collection would have named beside these trees,
        // in the order the trees arrive in.
        let mut projects: Vec<String> = Vec::new();
        for tree in &trees {
            if projects.last() != Some(&tree.project) {
                projects.push(tree.project.clone());
            }
        }
        let trees: Vec<Arc<Tree>> = trees.into_iter().map(Arc::new).collect();

        Snapshot {
            generated_at: Utc.with_ymd_and_hms(2026, 8, 30, 10, 22, 14).unwrap(),
            agents: a_provider(agents),
            filter: Filter::All,
            collected: trees.clone(),
            trees,
            projects,
            scope: Scope::default(),
            hidden_trees: Vec::new(),
            failed_projects: Vec::new(),
            unattributed,
            unconfigured: Vec::new(),
            conflicts: Vec::new(),
            projects_named_without_git: Vec::new(),
            read_at: BTreeMap::from([("summit-works".to_string(), read_at())]),
        }
    }

    /// When the fixture's tracker was read. Half a minute before the
    /// snapshot was generated, so a frame quoting the wrong one of the two
    /// says so rather than agreeing by coincidence.
    pub(super) fn read_at() -> DateTime<Utc> {
        Utc.with_ymd_and_hms(2026, 8, 30, 10, 21, 44).unwrap()
    }

    /// The instant a test frame is drawn at: the snapshot's own. The read
    /// behind it is half a minute older, so a project line drawn from it is
    /// half a minute stale.
    pub(super) fn drawn_at() -> DateTime<Utc> {
        Utc.with_ymd_and_hms(2026, 8, 30, 10, 22, 14).unwrap()
    }

    /// Nothing has been read and nothing is being read, for the lines that
    /// say nothing about either.
    static NOTHING_READ: BTreeMap<String, DateTime<Utc>> = BTreeMap::new();

    pub(super) fn at_rest() -> Reads<'static> {
        Reads::new(&NOTHING_READ, &[], drawn_at())
    }

    /// One tree of `children` open beads under an in-flight root.
    pub(super) fn grove(children: usize) -> Tree {
        let mut beads = vec![node(
            "smt-4kd3p",
            "lift the ground station",
            Status::InProgress,
        )];
        for child in 1..=children {
            beads.push(node(
                &format!("smt-4kd3p.{child}"),
                &format!("bead number {child}"),
                Status::Open,
            ));
        }

        Tree {
            counts: counts(0, beads.len(), 0, 0),
            children: under_the_root(&beads),
            beads,
            ..tree(
                "summit-works",
                "smt-4kd3p",
                "lift the ground station",
                counts(0, 0, 0, 0),
            )
        }
    }

    /// The ways down a tree of one root over leaves: every other bead hangs
    /// under the first, and nothing hangs under them.
    pub(super) fn under_the_root(beads: &[Node]) -> Vec<Vec<Link>> {
        let mut children = vec![(1..beads.len())
            .map(|bead| Link {
                bead,
                edge: Edge::ParentChild,
                first: true,
            })
            .collect()];
        children.resize(beads.len(), Vec::new());
        children
    }

    /// A forest with its first tree opened by hand. Nothing in these fixtures
    /// is staffed, so the fold default rests every tree as its header, and
    /// what these tests are about is the rows under one.
    pub(super) fn opened(snapshot: &Snapshot) -> Forest {
        let mut forest = flatten(snapshot.clone());
        forest.apply(Action::ToggleFold);
        forest
    }

    pub(super) fn frame_of(forest: &Forest, width: u16, height: u16) -> Painted {
        frame_collecting(forest, &[], width, height)
    }

    /// A collection reading `wanted`, asked for at the instant the frame is
    /// drawn — so it is a collection under way rather than one that has
    /// stopped answering.
    pub(super) fn reading(wanted: Wanted) -> Awaited {
        Awaited {
            wanted,
            asked_at: drawn_at(),
            patience: PATIENCE,
        }
    }

    /// How long the collections these tests build may go unanswered. A round
    /// number the instants are written against, rather than the configured
    /// default: what they assert is which mark a wait produces, not what the
    /// deadline is.
    pub(super) const PATIENCE: chrono::TimeDelta = chrono::TimeDelta::seconds(30);

    /// The same frame with a collection in flight, so a project line the
    /// collection names says so.
    pub(super) fn frame_collecting(
        forest: &Forest,
        collecting: &[Awaited],
        width: u16,
        height: u16,
    ) -> Painted {
        frame_with(forest, &[], collecting, width, height)
    }

    fn frame_with(
        forest: &Forest,
        standing: &[Notice],
        collecting: &[Awaited],
        width: u16,
        height: u16,
    ) -> Painted {
        let keys = a_key_row();
        Painted::drawn_by(width, height, |frame| {
            draw(
                frame,
                frame.area(),
                forest,
                &Layout::default(),
                collecting,
                drawn_at(),
                Foot {
                    standing,
                    said: None,
                    prompt: None,
                    keys: &keys,
                },
            );
        })
    }

    /// The whole screen, character for character: five rows of forest, four of
    /// reserved tail, and the foot.
    #[test]
    fn a_frame_is_the_forest_the_tails_reserved_band_and_the_foot() {
        let forest = opened(&snapshot(
            vec![grove(2)],
            Vec::new(),
            ProviderState::NotAnswering,
        ));

        assert_eq!(
            frame_of(&forest, 60, 10).rows(),
            vec![
                "▾ summit-works  ✓ 30s ago                                0/3",
                "  └── ◐ smt-4kd3p  lift the ground station               0/3",
                "      ├── ○ .1         bead number 1                        ",
                "      └── ○ .2         bead number 2                        ",
                "                                                            ",
                "                                                            ",
                "                                                            ",
                "                                                            ",
                "                                                            ",
                "⚠ no herdr session · which agents are alive is unknown      ",
            ]
        );
    }

    /// A project's fraction is over every tree it holds, said in the words the
    /// reader sees: the filter takes a tree off the screen and leaves the
    /// count where it was. The group line is what says the filter is holding
    /// one back, so a fixture that quietly showed both trees fails here rather
    /// than agreeing with the fraction by coincidence.
    #[test]
    fn a_projects_fraction_counts_the_tree_the_filter_holds_back() {
        let beads = vec![node("smt-7bv1n", "raise the mast", Status::Open)];
        let mut held_back = tree(
            "summit-works",
            "smt-7bv1n",
            "raise the mast",
            Counts::over(&beads),
        );
        held_back.children = under_the_root(&beads);
        held_back.beads = beads;

        let shown = grove(2);
        let mut snapshot = snapshot(
            vec![shown.clone(), held_back.clone()],
            Vec::new(),
            ProviderState::Answering,
        );
        snapshot.filter = Filter::LiveAgents;
        snapshot.trees = vec![Arc::new(shown)];
        snapshot.hidden_trees = vec![HiddenTree::of(&held_back)];

        let frame = frame_of(&flatten(snapshot), 60, 8).rows();

        assert!(
            frame
                .iter()
                .any(|row| row.contains("1 tree with no live agent")),
            "{frame:#?}"
        );
        assert!(
            frame[0].contains("0/4"),
            "three beads on screen and one held back is four: {frame:#?}"
        );
    }

    /// The bead's own case, at the whole-frame level: a `bdi` that could not
    /// open its socket says so at the foot, and it is the same row and the
    /// same shape a herdr failure uses. Nothing above the foot changes,
    /// because nothing above the foot is wrong.
    #[test]
    fn a_socket_that_would_not_open_is_said_at_the_foot_of_the_frame() {
        let forest = opened(&snapshot(
            vec![grove(2)],
            Vec::new(),
            ProviderState::Answering,
        ));

        assert_eq!(
            frame_with(&forest, &[Notice::NoInboundChannel], &[], 80, 10).rows(),
            vec![
                "▾ summit-works  ✓ 30s ago                                                    0/3",
                "  └── ◐ smt-4kd3p  lift the ground station                                   0/3",
                "      ├── ○ .1         bead number 1                                            ",
                "      └── ○ .2         bead number 2                                            ",
                "                                                                                ",
                "                                                                                ",
                "                                                                                ",
                "                                                                                ",
                "                                                                                ",
                "⚠ nothing can tell bdi a project changed · every project is polled instead      ",
            ]
        );
    }

    /// The definition of done's first case, at the whole-frame level: a narrow
    /// screen cuts every row and wraps none, so the row count on screen still
    /// matches the line count in the forest.
    #[test]
    fn a_narrow_frame_cuts_every_row_and_wraps_none() {
        let forest = opened(&snapshot(
            vec![grove(2)],
            Vec::new(),
            ProviderState::Answering,
        ));
        let frame = frame_of(&forest, 24, 10).rows();

        assert_eq!(
            frame[..4].to_vec(),
            vec![
                "▾ summit-works       0/3",
                "  └── ◐ smt-4kd3p    0/3",
                "      ├── ○ .1         …",
                "      └── ○ .2         …",
            ]
        );
        assert!(
            frame[4..9].iter().all(|row| row.trim().is_empty()),
            "{frame:?}"
        );
    }

    /// The definition of done's second case: however far the selection moves,
    /// the row it is on is drawn.
    #[test]
    fn the_selected_row_is_drawn_wherever_the_selection_has_moved_to() {
        let mut forest = flatten(snapshot(
            vec![grove(40)],
            Vec::new(),
            ProviderState::Answering,
        ));

        for motion in [Motion::LastRow, Motion::FirstRow, Motion::HalfScreenDown] {
            forest.apply(Action::Move(motion));
            let at = forest.selected_line();
            let said = match &forest.lines()[at].content {
                Content::Bead(row) => row.title.clone(),
                Content::Project(line) => line.project.clone(),
                other => panic!("unexpected line under the selection: {other:?}"),
            };
            let frame = frame_of(&forest, 60, 10).rows();

            assert!(
                frame.iter().any(|row| row.contains(&said)),
                "{motion:?} put line {at} ({said}) off screen: {frame:?}"
            );
        }
    }

    /// Which row the cursor is on, and only that one.
    ///
    /// `Fitted::selected` reverses the row's whole style and moves not one
    /// word, so nothing in the symbols says where the cursor is: a frame that
    /// drew every row selected but the selected one reads the same as a
    /// correct one.
    #[test]
    fn the_row_under_the_cursor_is_the_only_one_drawn_reversed() {
        let mut forest = opened(&snapshot(
            vec![grove(2)],
            Vec::new(),
            ProviderState::Answering,
        ));
        forest.apply(Action::Move(Motion::FirstRow));
        forest.apply(Action::Move(Motion::NextRow));
        let selected = forest.selected_line();
        let lines = forest.lines().len();

        let frame = frame_of(&forest, 60, 10);

        for at in 0..lines {
            let reversed = frame
                .row(at)
                .iter()
                .all(|run| run.style.add_modifier.contains(Modifier::REVERSED));

            assert_eq!(
                reversed,
                at == selected,
                "row {at} of {lines}, cursor on {selected}: {:?}",
                frame.row(at)
            );
        }
    }

    /// The definition of done's third case: a root nobody could read renders
    /// as the root it is, the reason it failed, and — under its project's
    /// line, after the root — the panes still working there.
    #[test]
    fn a_root_that_would_not_read_draws_its_reason_and_its_projects_panes() {
        let failed =
            Tree::tracker_unreachable("summit-works", "smt-4kd3p", TrackerFailure::Unavailable);
        let forest = flatten(snapshot(
            vec![failed],
            vec![pane("wCM:p9", PaneStatus::Working)],
            ProviderState::Answering,
        ));
        let frame = frame_of(&forest, 77, 8).rows();

        assert_eq!(
            frame[..4],
            [
                "▾ summit-works  ⚠ 30s ago                                                    ",
                "  ├── ⚠ smt-4kd3p  the tracker did not answer                                ",
                "  └── ⚠ 1 unattributed pane                                                  ",
                "      └── ◍ wCM:p9 working  /tmp/bdi-ground/summit-works                     ",
            ]
        );
    }

    /// An unread root has no row of its own to measure, so its id is padded to
    /// the id column the bead rows settled between them: the reason beside it
    /// starts where their titles do.
    #[test]
    fn an_unread_roots_reason_starts_where_the_bead_rows_titles_do() {
        let unreadable =
            Tree::tracker_unreachable("summit-works", "smt-7", TrackerFailure::Unavailable);
        let forest = opened(&snapshot(
            vec![grove(1), unreadable],
            Vec::new(),
            ProviderState::Answering,
        ));
        let frame = frame_of(&forest, 70, 7).rows();

        assert_eq!(
            frame[1..4],
            [
                "  ├── ◐ smt-4kd3p  lift the ground station                         0/2",
                "  │   └── ○ .1         bead number 1                                  ",
                "  └── ⚠ smt-7      the tracker did not answer                         ",
            ]
        );
    }

    /// A root with nothing under it has no fold for a marker to stand for, so
    /// it draws none — and it still starts in the column its siblings start
    /// in, because a reader running down a project's roots finds every one of
    /// them in the same place.
    #[test]
    fn a_root_with_nothing_under_it_draws_no_marker_and_still_lines_up() {
        let unreadable =
            Tree::tracker_unreachable("summit-works", "smt-4kd3p", TrackerFailure::Unavailable);
        let forest = flatten(snapshot(
            vec![grove(2), unreadable],
            Vec::new(),
            ProviderState::Answering,
        ));
        let frame = frame_of(&forest, 90, 5).rows();
        // The project's own line wears the warning too — one of its roots
        // would not read, which is what this fixture is — so the root is
        // found by the warning and its own id together.
        let unread = frame
            .iter()
            .position(|row| row.contains(WARNING) && row.contains("smt-4kd3p"))
            .expect("the root that would not read");
        let column = |row: &str| {
            let byte = row.find("smt-4kd3p").expect("the root on the row");
            row[..byte].chars().count()
        };

        assert!(
            !frame[unread].contains(SHUT.trim()),
            "nothing opens this root, so nothing should say it is shut: {:?}",
            frame[unread]
        );
        assert_eq!(
            column(&frame[unread]),
            column(&frame[1]),
            "the mark stands where a status glyph does:\n{}\n{}",
            frame[1],
            frame[unread]
        );
    }
}