day-core 0.6.2

// Copyright © The Daybrite Project
// SPDX-License-Identifier: MPL-2.0

//! Tests that run inside a built Day app (docs/testing.md): a [`Case`] is a page plus a drive,
//! or a headless run, declared next to the code it tests with `#[day::test]` and collected in a
//! registry. The dayscript engine runs them on a real toolkit under `day test`; the mock
//! harness runs the same functions under `cargo test`. Nothing here knows how a step is
//! executed: a [`DriveBackend`] does, and the engine supplies one.
//!
//! A test's name is its function's, with hyphens for underscores (`button_status` runs as
//! `button-status`): the registry entry carries the identifier, so a tool reading the source
//! (`day test --list`, an editor) and the app agree without either one running the other.

use std::cell::RefCell;
use std::future::Future;
use std::pin::Pin;
use std::rc::Rc;

use day_spec::Cap;

use crate::AnyPiece;

/// A failed assertion, with the sentence the report shows.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct Fail(pub String);

impl std::fmt::Display for Fail {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_str(&self.0)
    }
}

impl From<String> for Fail {
    fn from(s: String) -> Self {
        Fail(s)
    }
}

impl From<&str> for Fail {
    fn from(s: &str) -> Self {
        Fail(s.to_owned())
    }
}

/// What a test's body answers.
pub type TestResult = Result<(), Fail>;

/// What a drive asks of the app, in dayscript's vocabulary. The engine maps each to the step
/// a script would send, so a drive and a script mean the same thing by the same words.
#[derive(Clone, Debug, PartialEq)]
pub enum DriveOp {
    Tap(String),
    Input(String, String),
    Toggle(String, bool),
    SetValue(String, f64),
    Select(String, usize),
    Focus(String),
    Submit(String),
    Navigate(String),
    WaitIdle,
    Pause(f64),
    /// Capture the window under this name into the test's record.
    Shot(String),
    AssertText(String, String),
    AssertVisible(String),
    AssertMissing(String),
    /// That an element is not on screen: missing, empty, or natively hidden.
    AssertHidden(String),
    /// A pointer entering an element, at a point in it or (for `None`) its center.
    Hover(String, Option<(f64, f64)>),
    /// The pointer leaving an element.
    HoverLeave(String),
    /// A two-finger pan over an element, by this much in total.
    Pan(String, f64, f64),
    /// A pinch over an element, to this cumulative scale.
    Pinch(String, f64),
    /// A drag over an element, from one point to another in its coordinates.
    Drag(String, (f64, f64), (f64, f64)),
    /// A tap at a point in an element's coordinates.
    TapAt(String, f64, f64),
    /// A key press, to an element or (for `None`) to whatever holds focus.
    Key(Option<String>, String),
    /// That the app announced this text to the screen reader during the run.
    AssertAnnounced(String),
    AssertValue(String, f64),
    /// A toggle's state.
    AssertOn(String, bool),
    AssertFocused(String, bool),
    AssertRoute(String),
    A11yAudit(Option<String>),
    /// The native widget's own state, as the platform reports it.
    AssertNative(String, NativeExpect),
    /// An element's frame, in Day's layout and natively.
    AssertFrame(String, FrameExpect),
    /// The color at a point of an element (fractions of its frame), `#rrggbb`.
    SamplePixel(String, f64, f64, String),
    /// A URL the app asked to open during the run.
    AssertOpenedUrl(String),
    /// Activate a list's row (a double click, Return, a tap on the phones), by position.
    Activate(String, usize),
    /// Move a list's row from one position to another, as a drag-to-reorder commits it.
    Reorder(String, usize, usize),
    /// Delete a list's row, as the platform's delete gesture commits it.
    DeleteRow(String, usize),
    /// Press a row's swipe action: the list, the row, the edge (`true` = leading) and the
    /// action's position in that edge's offer.
    SwipeRow(String, usize, bool, usize),
    /// Scroll a scroll view or list to an edge (`"top"`, `"bottom"`, `"leading"`, `"trailing"`).
    ScrollTo(String, String),
    /// Expand or collapse a tree's row, named by its row id.
    Expand(String, String, bool),
    /// Go back one page in the innermost navigation stack.
    NavBack,
    /// Move a tree's row (by row id) under a parent (`None` = the root) at a position.
    TreeMove(String, String, Option<String>, Option<usize>),
    /// Choose an item, by label, from an element's context menu.
    ContextMenu(String, String),
    /// Choose an app-menu item by its id.
    Menu(String),
    /// Press a toolbar button, by item id.
    ToolbarPress(String),
    /// Set a toolbar toggle, by item id.
    ToolbarToggle(String, bool),
    /// Answer presentations natively (`false`) or hold them for `respond` (`true`).
    DialogScripted(bool),
    /// That a presentation is pending, with this title where one is given.
    AssertPresented(Option<String>),
    /// Answer the pending presentation: a button by position, or dismiss it (`None`).
    Respond(Option<usize>),
    /// Confirm a prompt with text (including an empty string).
    RespondText(String),
}

/// What [`Drive::assert_frame`] expects of an element's frame, in points; only the fields set
/// are checked. `x`/`y` are relative to `relative_to`'s origin, or the window content's.
#[derive(Clone, Debug, Default, PartialEq)]
pub struct FrameExpect {
    pub width: Option<f64>,
    pub height: Option<f64>,
    pub x: Option<f64>,
    pub y: Option<f64>,
    /// The element whose origin `x`/`y` are measured from.
    pub relative_to: Option<String>,
    /// How far each value may be off (default 1 point).
    pub tolerance: Option<f64>,
}

/// What [`Drive::assert_native`] expects the native widget to report; only the fields set are
/// checked (docs/testing.md).
#[derive(Clone, Debug, Default, PartialEq)]
pub struct NativeExpect {
    /// The text the widget displays.
    pub text: Option<String>,
    /// A slider's or progress indicator's value.
    pub number: Option<f64>,
    /// A toggle's state, or a button's selected state.
    pub checked: Option<bool>,
    /// Whether the widget takes input.
    pub enabled: Option<bool>,
    /// Whether the widget is shown.
    pub visible: Option<bool>,
}

/// The future one drive op resolves to.
pub type OpFuture = Pin<Box<dyn Future<Output = TestResult>>>;

/// Executes [`DriveOp`]s. The engine's backend runs each as the matching dayscript step on the
/// main thread and waits, asynchronously, through the step's retry window; the mock harness
/// uses the same backend against the mock toolkit.
pub trait DriveBackend {
    fn run(&self, op: DriveOp) -> OpFuture;
}

/// The handle a test drives the app with. Every method awaits the op and fails the test with
/// the step's own message when the op fails after its retry window.
#[derive(Clone)]
pub struct Drive {
    backend: Rc<dyn DriveBackend>,
}

impl Drive {
    /// A drive over `backend`; the engine and the mock harness build one per test.
    pub fn new(backend: Rc<dyn DriveBackend>) -> Self {
        Drive { backend }
    }

    fn op(&self, op: DriveOp) -> OpFuture {
        self.backend.run(op)
    }

    pub fn tap(&self, id: &str) -> OpFuture {
        self.op(DriveOp::Tap(id.into()))
    }
    /// Type `text` into the field, replacing what it holds.
    pub fn input(&self, id: &str, text: &str) -> OpFuture {
        self.op(DriveOp::Input(id.into(), text.into()))
    }
    pub fn toggle(&self, id: &str, on: bool) -> OpFuture {
        self.op(DriveOp::Toggle(id.into(), on))
    }
    pub fn set_value(&self, id: &str, value: f64) -> OpFuture {
        self.op(DriveOp::SetValue(id.into(), value))
    }
    pub fn select(&self, id: &str, index: usize) -> OpFuture {
        self.op(DriveOp::Select(id.into(), index))
    }
    pub fn focus(&self, id: &str) -> OpFuture {
        self.op(DriveOp::Focus(id.into()))
    }
    pub fn submit(&self, id: &str) -> OpFuture {
        self.op(DriveOp::Submit(id.into()))
    }
    pub fn navigate(&self, route: &str) -> OpFuture {
        self.op(DriveOp::Navigate(route.into()))
    }
    /// Let native transitions settle.
    pub fn wait_idle(&self) -> OpFuture {
        self.op(DriveOp::WaitIdle)
    }
    pub fn pause(&self, secs: f64) -> OpFuture {
        self.op(DriveOp::Pause(secs))
    }
    /// Capture the window as `name`; the capture rides the test's record to the runner.
    pub fn shot(&self, name: &str) -> OpFuture {
        self.op(DriveOp::Shot(name.into()))
    }
    pub fn assert_text(&self, id: &str, text: &str) -> OpFuture {
        self.op(DriveOp::AssertText(id.into(), text.into()))
    }
    pub fn assert_visible(&self, id: &str) -> OpFuture {
        self.op(DriveOp::AssertVisible(id.into()))
    }
    pub fn assert_missing(&self, id: &str) -> OpFuture {
        self.op(DriveOp::AssertMissing(id.into()))
    }
    /// The pointer entering `id` at (`x`, `y`) in its coordinates (its center for `None`).
    pub fn hover(&self, id: &str, at: Option<(f64, f64)>) -> OpFuture {
        self.op(DriveOp::Hover(id.into(), at))
    }
    /// The pointer leaving `id`.
    pub fn hover_leave(&self, id: &str) -> OpFuture {
        self.op(DriveOp::HoverLeave(id.into()))
    }
    /// A two-finger pan over `id` by (`dx`, `dy`) in total.
    pub fn pan(&self, id: &str, dx: f64, dy: f64) -> OpFuture {
        self.op(DriveOp::Pan(id.into(), dx, dy))
    }
    /// A pinch over `id` to `scale` (cumulative; 1 = unchanged).
    pub fn pinch(&self, id: &str, scale: f64) -> OpFuture {
        self.op(DriveOp::Pinch(id.into(), scale))
    }
    /// A pointer drag over `id` from `from` to `to`, in its coordinates.
    pub fn drag(&self, id: &str, from: (f64, f64), to: (f64, f64)) -> OpFuture {
        self.op(DriveOp::Drag(id.into(), from, to))
    }
    /// A tap at (`x`, `y`) in `id`'s coordinates.
    pub fn tap_at(&self, id: &str, x: f64, y: f64) -> OpFuture {
        self.op(DriveOp::TapAt(id.into(), x, y))
    }
    /// A key press (web `KeyboardEvent.key` names: `"Enter"`, `"ArrowRight"`, `"a"`) to `id`,
    /// or to whatever holds focus for `None`.
    pub fn key(&self, id: Option<&str>, key: &str) -> OpFuture {
        self.op(DriveOp::Key(id.map(str::to_owned), key.into()))
    }
    /// That the app announced `text` to the screen reader during the run.
    pub fn assert_announced(&self, text: &str) -> OpFuture {
        self.op(DriveOp::AssertAnnounced(text.into()))
    }
    /// That an element is not on screen: missing, with an empty frame, or hidden natively (a
    /// collapsed pane a toolkit keeps built).
    pub fn assert_hidden(&self, id: &str) -> OpFuture {
        self.op(DriveOp::AssertHidden(id.into()))
    }
    pub fn assert_value(&self, id: &str, value: f64) -> OpFuture {
        self.op(DriveOp::AssertValue(id.into(), value))
    }
    /// A toggle's on/off state.
    pub fn assert_on(&self, id: &str, on: bool) -> OpFuture {
        self.op(DriveOp::AssertOn(id.into(), on))
    }
    pub fn assert_focused(&self, id: &str, focused: bool) -> OpFuture {
        self.op(DriveOp::AssertFocused(id.into(), focused))
    }
    pub fn assert_route(&self, route: &str) -> OpFuture {
        self.op(DriveOp::AssertRoute(route.into()))
    }
    /// Diff the native accessibility tree against Day's expectation for `id` (all id'd
    /// nodes when `None`), where the toolkit can read its tree back.
    pub fn a11y_audit(&self, id: Option<&str>) -> OpFuture {
        self.op(DriveOp::A11yAudit(id.map(str::to_owned)))
    }

    /// The native widget's own state, as the platform reports it (docs/testing.md). A field
    /// the toolkit cannot read is recorded in the report as unread rather than failed. In a
    /// conformance run `assert_text`, `assert_value` and `assert_on` check the native widget
    /// too; this is for what they do not cover.
    pub fn assert_native(&self, id: &str, expect: NativeExpect) -> OpFuture {
        self.op(DriveOp::AssertNative(id.into(), expect))
    }
    /// The element's frame in Day's layout and, where the toolkit reads it back, natively.
    pub fn assert_frame(&self, id: &str, expect: FrameExpect) -> OpFuture {
        self.op(DriveOp::AssertFrame(id.into(), expect))
    }
    /// The element's size, the common case of [`Drive::assert_frame`].
    pub fn assert_size(&self, id: &str, width: f64, height: f64) -> OpFuture {
        self.assert_frame(
            id,
            FrameExpect {
                width: Some(width),
                height: Some(height),
                ..Default::default()
            },
        )
    }
    /// The color drawn at (`x`, `y`), fractions of the element's frame, as `#rrggbb`. Passes as
    /// unread where the toolkit has no capture.
    pub fn sample_pixel(&self, id: &str, x: f64, y: f64, color: &str) -> OpFuture {
        self.op(DriveOp::SamplePixel(id.into(), x, y, color.into()))
    }
    /// That the app asked to open `url` (a link, `day::open_url`) during the run; in a run
    /// nothing actually opens.
    pub fn assert_opened_url(&self, url: &str) -> OpFuture {
        self.op(DriveOp::AssertOpenedUrl(url.into()))
    }
    /// Whether the element takes input, in Day's tree and in the native widget.
    pub fn assert_enabled(&self, id: &str, enabled: bool) -> OpFuture {
        self.assert_native(
            id,
            NativeExpect {
                enabled: Some(enabled),
                ..Default::default()
            },
        )
    }

    /// Activate a list's row by position: what a double click, Return or a phone's tap commits.
    pub fn activate(&self, id: &str, index: usize) -> OpFuture {
        self.op(DriveOp::Activate(id.into(), index))
    }
    /// Move a list's row from `from` to `to`, as a native drag-to-reorder commits it.
    pub fn reorder(&self, id: &str, from: usize, to: usize) -> OpFuture {
        self.op(DriveOp::Reorder(id.into(), from, to))
    }
    /// Delete a list's row, as the platform's delete gesture commits it.
    pub fn delete_row(&self, id: &str, row: usize) -> OpFuture {
        self.op(DriveOp::DeleteRow(id.into(), row))
    }
    /// Press the `action`th swipe action on a list row's leading or trailing edge.
    pub fn swipe_row(&self, id: &str, row: usize, leading: bool, action: usize) -> OpFuture {
        self.op(DriveOp::SwipeRow(id.into(), row, leading, action))
    }
    /// Scroll a scroll view or list to an edge: `"top"`, `"bottom"`, `"leading"`, `"trailing"`.
    pub fn scroll_to(&self, id: &str, edge: &str) -> OpFuture {
        self.op(DriveOp::ScrollTo(id.into(), edge.into()))
    }
    /// Expand or collapse a tree's row, named by its row id.
    pub fn expand(&self, id: &str, row: &str, expanded: bool) -> OpFuture {
        self.op(DriveOp::Expand(id.into(), row.into(), expanded))
    }
    /// Go back one page in the innermost navigation stack.
    pub fn nav_back(&self) -> OpFuture {
        self.op(DriveOp::NavBack)
    }
    /// Move a tree's row (by row id) under `parent` (`None` = the root level), at `index` among
    /// its new siblings (`None` = last), as a native drag commits it.
    pub fn tree_move(
        &self,
        id: &str,
        row: &str,
        parent: Option<&str>,
        index: Option<usize>,
    ) -> OpFuture {
        self.op(DriveOp::TreeMove(
            id.into(),
            row.into(),
            parent.map(str::to_owned),
            index,
        ))
    }

    /// Choose the item labeled `item` from `id`'s context menu, as a right click (or long
    /// press) and a choice would.
    pub fn context_menu(&self, id: &str, item: &str) -> OpFuture {
        self.op(DriveOp::ContextMenu(id.into(), item.into()))
    }
    /// Choose an app-menu item by the id the app gave it (`MenuEntry::id`).
    pub fn menu(&self, item_id: &str) -> OpFuture {
        self.op(DriveOp::Menu(item_id.into()))
    }
    /// Press the toolbar button `item`.
    pub fn toolbar_press(&self, item: &str) -> OpFuture {
        self.op(DriveOp::ToolbarPress(item.into()))
    }
    /// Turn the toolbar toggle `item` on or off.
    pub fn toolbar_toggle(&self, item: &str, on: bool) -> OpFuture {
        self.op(DriveOp::ToolbarToggle(item.into(), on))
    }
    /// Show presentations natively (`false`, the default) or hold them for
    /// [`Drive::respond`] without any native dialog (`true`). In native mode `respond` still
    /// answers, and the toolkit dismisses the dialog it showed.
    pub fn dialogs_scripted(&self, scripted: bool) -> OpFuture {
        self.op(DriveOp::DialogScripted(scripted))
    }
    /// That a dialog or picker is pending, titled `title` where one is given.
    pub fn assert_presented(&self, title: Option<&str>) -> OpFuture {
        self.op(DriveOp::AssertPresented(title.map(str::to_owned)))
    }
    /// Answer the pending dialog with the button at `button` (presentation order), or dismiss
    /// it for `None`.
    pub fn respond(&self, button: Option<usize>) -> OpFuture {
        self.op(DriveOp::Respond(button))
    }

    /// Confirm a pending text prompt.
    pub fn respond_text(&self, text: &str) -> OpFuture {
        self.op(DriveOp::RespondText(text.into()))
    }

    /// A plain assertion for a headless test: fails with `what` when `ok` is false.
    pub fn check(&self, ok: bool, what: &str) -> TestResult {
        if ok { Ok(()) } else { Err(Fail(what.into())) }
    }
    /// Equality for a headless test, naming both sides on a mismatch.
    pub fn check_eq<T: PartialEq + std::fmt::Debug>(&self, got: T, want: T) -> TestResult {
        if got == want {
            Ok(())
        } else {
            Err(Fail(format!("{got:?} ≠ expected {want:?}")))
        }
    }
}

/// Whether a case shows a page and drives it, or runs with no page.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum TestKind {
    Gui,
    Headless,
}

type Body = Rc<dyn Fn(Drive) -> Pin<Box<dyn Future<Output = TestResult>>>>;

/// One test: what it proves, what it needs, the page it shows and the body that drives it.
/// Built by a `#[day::test]` function each time the test runs, so the signals a page and its
/// drive share are fresh per run; the registry names it after that function.
#[derive(Clone)]
pub struct Case {
    name: String,
    kind: TestKind,
    proves: Vec<String>,
    requires: Vec<Cap>,
    /// Supports the case needs beyond a `Cap`: a piece's own `support()` answer, named.
    requires_support: Vec<(String, fn() -> day_spec::Support)>,
    page: Option<Rc<dyn Fn() -> AnyPiece>>,
    shots: Vec<String>,
    body: Option<Body>,
    timeout_secs: Option<f64>,
}

impl Default for Case {
    fn default() -> Self {
        Case::new()
    }
}

impl Case {
    /// A GUI case: a page the app's test host shows while the case runs, and a drive against it.
    pub fn new() -> Self {
        Case {
            name: String::new(),
            kind: TestKind::Gui,
            proves: Vec::new(),
            requires: Vec::new(),
            requires_support: Vec::new(),
            page: None,
            shots: Vec::new(),
            body: None,
            timeout_secs: None,
        }
    }
    /// A test with no page: app logic run inside the app's own environment.
    pub fn headless() -> Self {
        Case {
            kind: TestKind::Headless,
            ..Case::new()
        }
    }
    /// How long the case may take, page and drive together, before it fails as timed out.
    /// Unset, the run's default applies (30 s, or what `day test --case-timeout` says).
    pub fn timeout(mut self, secs: f64) -> Self {
        self.timeout_secs = Some(secs);
        self
    }
    /// The piece kind this case is the proof of (`kinds::BUTTON`); a pass marks the kind
    /// on this toolkit in the coverage tables.
    pub fn proves(mut self, kind: &str) -> Self {
        self.proves.push(format!("kind:{kind}"));
        self
    }
    /// The capability this case proves.
    pub fn proves_cap(mut self, cap: Cap) -> Self {
        self.proves.push(format!("cap:{cap:?}"));
        self
    }
    /// The `Decorate` modifier this case proves (`"padding"`).
    pub fn proves_modifier(mut self, modifier: &str) -> Self {
        self.proves.push(format!("modifier:{modifier}"));
        self
    }
    /// The toolkit duty this case proves (`"set_input_traits"`).
    pub fn proves_duty(mut self, duty: &str) -> Self {
        self.proves.push(format!("duty:{duty}"));
        self
    }
    /// A capability the case needs; where the toolkit answers `Unsupported` the case is
    /// skipped with that reason rather than failed. The one way a case adapts to a toolkit.
    pub fn requires(mut self, cap: Cap) -> Self {
        self.requires.push(cap);
        self
    }
    /// A piece's own support the case needs (`day_piece_map::support`), named for the skip
    /// reason: where it answers `Unsupported` the case is skipped, as for [`Case::requires`].
    /// For a piece realized only where its platform ships the widget.
    pub fn requires_support(mut self, what: &str, support: fn() -> day_spec::Support) -> Self {
        self.requires_support.push((what.to_owned(), support));
        self
    }
    /// The first support this case needs that the running toolkit lacks, named.
    pub fn missing_support(&self) -> Option<String> {
        self.requires_support
            .iter()
            .find(|(_, f)| f() == day_spec::Support::Unsupported)
            .map(|(what, _)| what.clone())
    }
    /// The page the app shows for this case; any piece.
    pub fn page<P: crate::Piece>(mut self, page: impl Fn() -> P + 'static) -> Self {
        self.page = Some(Rc::new(move || AnyPiece::new(page())));
        self
    }
    /// A capture taken before the drive runs, once the page is shown.
    pub fn shot(mut self, name: &str) -> Self {
        self.shots.push(name.into());
        self
    }
    /// The drive: an async body over a [`Drive`], awaiting each step so the app's main loop
    /// runs between them (a transition settles, a capture paints) as it does between a
    /// script's steps.
    pub fn drive<F>(mut self, body: impl Fn(Drive) -> F + 'static) -> Self
    where
        F: Future<Output = TestResult> + 'static,
    {
        self.body = Some(Rc::new(move |d| Box::pin(body(d))));
        self
    }
    /// [`Case::drive`] under the name a headless test reads better with.
    pub fn run<F>(self, body: impl Fn(Drive) -> F + 'static) -> Self
    where
        F: Future<Output = TestResult> + 'static,
    {
        self.drive(body)
    }

    /// The name the registry gave the case: its function's, hyphenated. Empty for a case
    /// built outside the registry.
    pub fn name(&self) -> &str {
        &self.name
    }
    /// The case's own time limit, if it set one.
    pub fn timeout_secs(&self) -> Option<f64> {
        self.timeout_secs
    }
    pub fn kind(&self) -> TestKind {
        self.kind
    }
    /// The `kind:`, `cap:` and `duty:` keys this case proves, in the matrices' own spelling.
    pub fn proves_keys(&self) -> &[String] {
        &self.proves
    }
    pub fn requirements(&self) -> &[Cap] {
        &self.requires
    }
    /// The captures to take before the drive.
    pub fn shots(&self) -> &[String] {
        &self.shots
    }
    /// Build the case's page, if it has one.
    pub fn build_page(&self) -> Option<AnyPiece> {
        self.page.as_ref().map(|p| p())
    }
    /// Run the body over `drive`; a case with no body passes once its page showed.
    pub fn run_body(&self, drive: Drive) -> Pin<Box<dyn Future<Output = TestResult>>> {
        match &self.body {
            Some(body) => body(drive),
            None => Box::pin(async { Ok(()) }),
        }
    }
}

/// A registered test: the function that builds its [`Case`], and that function's identifier,
/// which is where the test's name comes from. Declared by `#[day::test]`.
#[derive(Clone, Copy)]
pub struct TestFn {
    ident: &'static str,
    build: fn() -> Case,
}

impl TestFn {
    /// An entry for `build`, named by `ident` (`stringify!` of the function or its path).
    pub const fn new(ident: &'static str, build: fn() -> Case) -> Self {
        TestFn { ident, build }
    }
    /// The test's name: the identifier's last path segment, with hyphens for underscores.
    pub fn name(&self) -> String {
        let last = self.ident.rsplit("::").next().unwrap_or(self.ident);
        last.trim().replace('_', "-")
    }
    /// A fresh case, named.
    pub fn case(&self) -> Case {
        let mut case = (self.build)();
        case.name = self.name();
        case
    }
}

mod registry;
pub use registry::validate_registry;
#[cfg(target_arch = "wasm32")]
pub use registry::{Registration, install_web_registry};

/// Every native `#[day::test]`, collected without runtime constructors.
#[cfg(not(target_arch = "wasm32"))]
#[linkme::distributed_slice]
pub static TESTS: [TestFn];

/// What a test host does when the active case changes: rebuild its content.
type HostNotify = Rc<dyn Fn()>;

day_reactive::tls_slots! {
    conformance;
    static RUNTIME: RefCell<Vec<TestFn>> = const { RefCell::new(Vec::new()) };
    /// The case the engine is driving, which the test host shows; its page shares its signals
    /// with the drive.
    static ACTIVE: RefCell<Option<Case>> = const { RefCell::new(None) };
    /// The mounted test host's rebuild, when the app shows one (`day::test_host`).
    static HOST: RefCell<Option<HostNotify>> = const { RefCell::new(None) };
    /// A panic raised while the host built the active case's page, for the runner to report.
    static PAGE_PANIC: RefCell<Option<String>> = const { RefCell::new(None) };
    /// The URLs the app asked to open while a test run was going on, when one is.
    static OPENED: RefCell<Option<Vec<String>>> = const { RefCell::new(None) };
    /// What the app announced to the screen reader while a test run was going on, when one is.
    static ANNOUNCED: RefCell<Option<Vec<String>>> = const { RefCell::new(None) };
}

/// Start or end a test run's interception of [`crate::open_url`]: while it is on, a URL the app
/// asks to open is recorded instead of opened, so `assert_opened_url` can check it and no
/// browser starts on the machine running the tests.
pub fn set_intercepting_urls(on: bool) {
    OPENED.with(|o| *o.borrow_mut() = on.then(Vec::new));
    ANNOUNCED.with(|a| *a.borrow_mut() = on.then(Vec::new));
}

/// Record a screen-reader announcement if a test run is going on. Unlike a URL it still goes
/// to the toolkit: announcing has no side effect a run must avoid, and the duty is what a case
/// proves.
pub fn note_announcement(text: &str) {
    ANNOUNCED.with(|a| {
        if let Some(list) = a.borrow_mut().as_mut() {
            list.push(text.to_owned());
        }
    });
}

/// The announcements made since the run began.
pub fn announcements() -> Vec<String> {
    ANNOUNCED.with(|a| a.borrow().clone().unwrap_or_default())
}

/// Record `url` if a test run is intercepting; whether it did.
pub fn intercept_open_url(url: &str) -> bool {
    OPENED.with(|o| match o.borrow_mut().as_mut() {
        Some(list) => {
            list.push(url.to_owned());
            true
        }
        None => false,
    })
}

/// The URLs opened (and intercepted) since the run began.
pub fn opened_urls() -> Vec<String> {
    OPENED.with(|o| o.borrow().clone().unwrap_or_default())
}

/// Add a synthetic case in a test harness. Application tests use `#[day::test]`.
pub fn register(test: TestFn) {
    RUNTIME.with(|r| {
        let mut r = r.borrow_mut();
        if !r.iter().any(|t| std::ptr::fn_addr_eq(t.build, test.build)) {
            r.push(test);
        }
    });
}

/// Every registered test, link-time and run-time ones together.
pub fn tests() -> Vec<TestFn> {
    let mut all: Vec<TestFn> = Vec::new();
    all.extend(registry::compiled_tests());
    RUNTIME.with(|r| {
        for t in r.borrow().iter() {
            if !all.iter().any(|a| std::ptr::fn_addr_eq(a.build, t.build)) {
                all.push(*t);
            }
        }
    });
    all
}

/// Every registered test as a fresh, named [`Case`], sorted by name.
pub fn cases() -> Vec<Case> {
    let mut cases: Vec<Case> = tests().iter().map(TestFn::case).collect();
    cases.sort_by(|a, b| a.name.cmp(&b.name));
    cases
}

/// Show `case` in the app's test host, built fresh, until the next call or [`clear_active`].
/// Answers false when the app mounts no test host, so the runner can say so.
pub fn set_active(case: Case) -> bool {
    ACTIVE.with(|a| *a.borrow_mut() = Some(case));
    PAGE_PANIC.with(|p| *p.borrow_mut() = None);
    notify_host()
}

/// Return the test host to the app's own content.
pub fn clear_active() {
    ACTIVE.with(|a| *a.borrow_mut() = None);
    notify_host();
}

fn notify_host() -> bool {
    let host = HOST.with(|h| h.borrow().clone());
    match host {
        Some(rebuild) => {
            rebuild();
            true
        }
        None => false,
    }
}

/// The active case, for the test host to build.
pub fn active() -> Option<Case> {
    ACTIVE.with(|a| a.borrow().clone())
}

/// Install the mounted test host's rebuild (`day::test_host` does, for the life of its
/// scope); `None` when it goes.
pub fn set_host(rebuild: Option<Rc<dyn Fn()>>) {
    HOST.with(|h| *h.borrow_mut() = rebuild);
}

/// Record a panic the test host caught while building the active case's page.
pub fn note_page_panic(message: String) {
    PAGE_PANIC.with(|p| *p.borrow_mut() = Some(message));
}

/// The panic, if any, the active case's page raised as it was built.
pub fn take_page_panic() -> Option<String> {
    PAGE_PANIC.with(|p| p.borrow_mut().take())
}

/// The sentence a caught panic's payload reads as.
pub fn panic_message(payload: &(dyn std::any::Any + Send)) -> String {
    if let Some(s) = payload.downcast_ref::<&str>() {
        (*s).to_owned()
    } else if let Some(s) = payload.downcast_ref::<String>() {
        s.clone()
    } else {
        "a panic with no message".to_owned()
    }
}

/// A fresh case for the test called `name`, for a person browsing an app's tests (the
/// conformance app's navigation does).
pub fn case_named(name: &str) -> Option<Case> {
    tests()
        .into_iter()
        .find(|t| t.name() == name)
        .map(|t| t.case())
}