monospace-cli 0.1.0

//! End-to-end checks that run the built binary as a subprocess.

use std::io::Write;
use std::path::PathBuf;
use std::process::{Command, Output};

/// Writes `contents` to a fresh file under the system temp directory, named after the calling
/// test so parallel tests never collide.
fn write_description(name: &str, contents: &str) -> PathBuf {
    let path = std::env::temp_dir().join(format!(
        "monospace-cli-test-{name}-{}.json",
        std::process::id()
    ));
    std::fs::File::create(&path)
        .and_then(|mut file| file.write_all(contents.as_bytes()))
        .expect("temp description file should be writable");
    path
}

/// Runs the built binary with `args` and returns its captured output.
fn run(args: &[&str]) -> Output {
    Command::new(env!("CARGO_BIN_EXE_monospace-cli"))
        .args(args)
        .output()
        .expect("the monospace-cli binary should be runnable")
}

/// The shipped demonstration's path, relative to the workspace root, so a test can pass it
/// explicitly the same way a user would.
const DEMO_PATH: &str = concat!(env!("CARGO_MANIFEST_DIR"), "/assets/demo.json");

/// The first of the eight captioned pictures the no-argument run prints, with its caption line and
/// the blank line after it stripped. Pins no caption's wording.
///
/// The seven pictures below it are appended rather than inserted, so the coordinates `char_at`
/// reads in the tests further down still name the same cells of the first picture — which is why
/// this function needs no change of its own when a picture is added.
///
/// Only the demonstration is captioned. A file's run is one picture and nothing else, so a test
/// that passes a path compares the whole of stdout.
fn first_demonstrated_picture(output: &str) -> String {
    let (first_block, _rest) = output
        .split_once("\n\n")
        .expect("two captioned pictures separated by a blank line");
    let (_caption, picture) = first_block
        .split_once('\n')
        .expect("a caption line precedes the picture");
    format!("{picture}\n")
}

/// An identity written as a string prints nothing to stdout, names the field on stderr, and fails.
///
/// **The refusal the whole wire change turns on**, and the wording is asserted rather than
/// described: `serde` alone reports `invalid type: string "#1", expected a nonzero u16`, which names
/// neither `id` nor what the file did wrong beyond its own words, so the reader puts the field in
/// front of it. `"#1"` is the spelling every description in this repository used until the change,
/// so it is the one a caller upgrading this format will have in hand.
///
/// **A `"shape"` and a `0` beside it**, in the same test rather than a second one: the three fields
/// share a deserializer and differ only in the name they print, so a reader that printed `id` for
/// all of them would pass a test on `id` alone. `two_entries_carrying_one_identity_are_both_read_and_both_drawn`
/// is the accepted cost beside this one: two entries may still carry one ordinal, and both are read.
#[test]
fn an_identity_written_as_a_string_is_refused_by_name_on_stderr_and_fails() {
    let a_string_id = write_description(
        "string-id",
        r##"{
            "next_id": 2,
            "shapes": [ { "kind": "box", "id": "#1", "at": { "x": 0, "y": 0 },
                          "size": { "width": 4, "height": 3 }, "stroke": "light" } ]
        }"##,
    );
    let a_string_shape = write_description(
        "string-shape",
        r##"{
            "next_id": 3,
            "shapes": [
                { "kind": "box", "id": 1, "at": { "x": 0, "y": 0 }, "size": { "width": 4, "height": 3 },
                  "stroke": "light" },
                { "kind": "connector", "id": 2,
                  "from": { "at": { "kind": "reference", "shape": "#1", "anchor": "right" },
                            "terminal": { "kind": "arm" } },
                  "to": { "at": { "kind": "point", "x": 8, "y": 1 }, "leaving": "left",
                          "terminal": { "kind": "arm" } },
                  "stroke": "light" } ]
        }"##,
    );

    for (path, named) in [(a_string_id, "id"), (a_string_shape, "shape")] {
        let output = run(&[path.to_str().expect("temp path should be valid UTF-8")]);

        assert!(
            !output.status.success(),
            "a name is not an ordinal and must fail"
        );
        assert!(output.stdout.is_empty(), "printed to stdout");
        let stderr = String::from_utf8_lossy(&output.stderr);
        assert!(
            stderr.contains(&format!("`{named}` is an ordinal")),
            "expected `{named}` to be named on stderr, got: {stderr}"
        );
        assert!(
            stderr.contains("\"#1\""),
            "expected the message to quote what the file said, got: {stderr}"
        );
    }
}

/// A `next_id` of zero prints nothing to stdout, names the field on stderr, and fails.
///
/// **Zero is the one value the format cannot express**, so the reader turns it away where the file
/// is rather than letting the counter stand at an identity no shape can carry. It is the same
/// refusal as the one beside it, in the one field that could otherwise have issued `"#0"` — which
/// the old reader held and handed out.
#[test]
fn a_next_id_of_zero_is_refused_by_name_on_stderr_and_fails() {
    let path = write_description(
        "zero-next-id",
        r#"{
            "next_id": 0,
            "shapes": [ { "kind": "box", "id": 1, "at": { "x": 0, "y": 0 },
                          "size": { "width": 4, "height": 3 }, "stroke": "light" } ]
        }"#,
    );

    let output = run(&[path.to_str().expect("temp path should be valid UTF-8")]);

    assert!(
        !output.status.success(),
        "zero is not an identity and must fail"
    );
    assert!(output.stdout.is_empty(), "printed to stdout");
    let stderr = String::from_utf8_lossy(&output.stderr);
    assert!(
        stderr.contains("`next_id` is an ordinal"),
        "expected `next_id` to be named on stderr, got: {stderr}"
    );
}

/// Two entries carrying the same `id` are **both** read. Both shapes are drawn, the run exits
/// successfully, and nothing is written to stderr.
///
/// **Pinned as an accepted cost rather than as a bug**, so a later slice that decides to report a
/// repeated identity has to say so rather than discover it. The diagram-level half — both held,
/// `get` returning the first — is `a_diagram_issues_the_counter_and_a_shape_added_under_a_callers_identity_does_not_move_it`
/// in `monospace-diagram`; this is the same cost arriving through a wire, where a reader might
/// plausibly have checked it and did not. An identity being a number did not change any of that:
/// `1` is no more unique than `"#1"` was, and nothing in the format checks it.
#[test]
fn two_entries_carrying_one_identity_are_both_read_and_both_drawn() {
    let path = write_description(
        "repeated-id",
        r#"{
            "next_id": 2,
            "shapes": [
                { "kind": "box", "id": 1, "at": { "x": 0, "y": 0 }, "size": { "width": 4, "height": 3 },
                  "stroke": "light" },
                { "kind": "box", "id": 1, "at": { "x": 2, "y": 1 }, "size": { "width": 4, "height": 3 },
                  "stroke": "light" }
            ]
        }"#,
    );

    let output = run(&[path.to_str().expect("temp path should be valid UTF-8")]);

    assert!(output.status.success(), "exited with {}", output.status);
    assert!(output.stderr.is_empty(), "wrote to stderr");
    // Both boxes draw: the first entry's border and the second one's, overlapping. A reader that
    // refused a repeated identity would have drawn one of them, and one that read the first and
    // dropped the second would draw a different picture than two of them do.
    let picture = String::from_utf8_lossy(&output.stdout);
    assert!(
        picture.contains("┌──┐") && picture.contains("└──┘") && picture.lines().count() >= 4,
        "both entries must draw, and a 6x4 window is four rows:\n{picture}"
    );
}

/// With no arguments, the binary prints the shipped demonstration and exits successfully, with
/// nothing on stderr.
#[test]
fn no_arguments_prints_the_demonstration_and_exits_successfully() {
    let output = run(&[]);

    assert!(output.status.success(), "exited with {}", output.status);
    assert!(!output.stdout.is_empty(), "printed nothing");
    assert!(output.stderr.is_empty(), "wrote to stderr");
}

/// Running with no arguments from a different working directory prints the same diagram, since
/// the demonstration is embedded in the binary rather than read from a path relative to the
/// working directory.
#[test]
fn running_from_a_different_working_directory_prints_the_same_diagram() {
    let from_temp_dir = Command::new(env!("CARGO_BIN_EXE_monospace-cli"))
        .current_dir(std::env::temp_dir())
        .output()
        .expect("the monospace-cli binary should be runnable from the temp directory");
    let from_manifest_dir = Command::new(env!("CARGO_BIN_EXE_monospace-cli"))
        .current_dir(env!("CARGO_MANIFEST_DIR"))
        .output()
        .expect("the monospace-cli binary should be runnable from its manifest directory");

    assert_eq!(from_temp_dir.stdout, from_manifest_dir.stdout);
}

/// The shipped demonstration's own path, passed explicitly, prints the picture the no-argument
/// run prints first — and stops there.
///
/// Byte-identical output from both runs was asked for once. It no longer holds, deliberately: the
/// caption and the moved shape belong to the demonstration, not to a description someone hands
/// the binary. What survives is that both parse the same text and draw it the same way.
#[test]
fn the_demo_path_passed_explicitly_prints_the_demonstrations_first_picture() {
    let no_arguments = run(&[]);
    let explicit_path = run(&[DEMO_PATH]);

    assert!(no_arguments.status.success());
    assert!(explicit_path.status.success());
    assert_eq!(
        String::from_utf8_lossy(&explicit_path.stdout),
        first_demonstrated_picture(&String::from_utf8_lossy(&no_arguments.stdout))
    );
}

/// An explicit path to a hand-written single-box file prints exactly that box.
///
/// **The size is passed on the command line**, because a path given no `--size` is drawn into this
/// binary's own window rather than the one its file names — which is the whole of what the default
/// is for, and why a test that wants a four-by-three picture has to say four by three.
#[test]
fn an_explicit_path_prints_the_hand_written_box() {
    let path = write_description(
        "one-box",
        r#"{
            "next_id": 2,
            "shapes": [
                { "kind": "box", "id": 1, "at": { "x": 0, "y": 0 }, "size": { "width": 4, "height": 3 },
                  "stroke": "light", "fill": "░" }
            ]
        }"#,
    );

    let output = run(&[
        "--size",
        "4x3",
        path.to_str().expect("temp path should be valid UTF-8"),
    ]);

    assert!(output.status.success(), "exited with {}", output.status);
    assert_eq!(
        String::from_utf8_lossy(&output.stdout),
        "┌──┐\n│░░│\n└──┘\n"
    );
    assert!(output.stderr.is_empty(), "wrote to stderr");
}

/// Rule 8 — a path and no `--size` draws into the demonstration's window.
///
/// **The file says `4x3` and the picture is fifty by seventeen.** That is the whole of the claim:
/// the default is a value this binary chose, and the description it was handed has nothing to say
/// about it. The picture is the box in the top-left corner of a window that reaches well past it,
/// which is what makes the default visible rather than asserted.
#[test]
fn a_path_and_no_size_draws_into_the_demonstrations_window() {
    let path = write_description(
        "default-window",
        r#"{
            "next_id": 2,
            "shapes": [
                { "kind": "box", "id": 1, "at": { "x": 0, "y": 0 }, "size": { "width": 4, "height": 3 },
                  "stroke": "light", "fill": "░" }
            ]
        }"#,
    );

    let output = run(&[path.to_str().expect("temp path should be valid UTF-8")]);

    assert!(output.status.success(), "exited with {}", output.status);
    let picture = String::from_utf8_lossy(&output.stdout);
    assert_eq!(
        picture.lines().count(),
        17,
        "the demonstration's window is seventeen rows tall: {picture}"
    );
    assert_eq!(
        picture.lines().next().expect("a first row").chars().count(),
        50,
        "and fifty columns wide: {picture}"
    );
    assert!(
        picture.starts_with("┌──┐"),
        "the box stands in the window's own top-left corner: {picture}"
    );
}

/// Rule 9 — the bare run draws into the demonstration's window, and nothing on the command line
/// changes that.
///
/// **The flags are read and the demonstration is drawn at its own size anyway**, because the two
/// callers are not the same caller: `cargo xtask render` always passes a size, so the default is
/// never what a generated picture uses, and the only person a bare run serves is one watching it.
/// A flag given to a run with no path is therefore not a window — it is a person typing.
#[test]
fn the_bare_run_draws_into_the_demonstrations_window() {
    let bare = run(&[]);
    let asked = run(&["--size", "6x4", "--origin", "1,1"]);

    for output in [&bare, &asked] {
        assert!(output.status.success(), "exited with {}", output.status);
        let stdout = String::from_utf8_lossy(&output.stdout);
        let first = first_demonstrated_picture(&stdout);
        assert_eq!(
            first.lines().count(),
            17,
            "the demonstration is seventeen rows tall whatever the command line says"
        );
        assert_eq!(
            first.lines().next().expect("a first row").chars().count(),
            50,
            "and fifty columns wide"
        );
    }
}

/// A size and an origin on the command line decide the window a path is drawn into, and the
/// window the file itself names is not what the picture is drawn at.
///
/// **The file says `6x4` and the command line says `4x3`, and the picture is four by three.** That
/// is the whole of the claim: a caller that names a window names it, and the description it drew
/// from has nothing to say about it.
///
/// The second half is the origin, and it is the window's corner rather than a move of the figure:
/// the same box at `(0, 0)` drawn into a window starting at `(1, 1)` is **outside** it, and what
/// survives is the part of the box the window holds. Measured rather than argued — the first draft
/// of this test expected the box to have traveled one cell right and down, and the binary drew
/// the corner of a box that had not moved at all.
///
/// The file's own window is still read and still used when no flag is given — which is what every
/// generated picture in this repository is drawn at until the markers carry their own — so the
/// assertion that matters is the one where the two disagree.
#[test]
fn a_size_and_an_origin_on_the_command_line_decide_the_window_a_path_is_drawn_into() {
    let path = write_description(
        "with-flags",
        r#"{
            "next_id": 2,
            "shapes": [
                { "kind": "box", "id": 1, "at": { "x": 0, "y": 0 }, "size": { "width": 4, "height": 3 },
                  "stroke": "light", "fill": "░" }
            ]
        }"#,
    );
    let path = path.to_str().expect("temp path should be valid UTF-8");

    let asked = run(&["--size", "4x3", path]);
    assert!(asked.status.success(), "exited with {}", asked.status);
    assert_eq!(
        String::from_utf8_lossy(&asked.stdout),
        "┌──┐\n│░░│\n└──┘\n",
        "the command line's size is the window, not the file's own"
    );

    let moved = run(&["--size", "4x3", "--origin", "1,1", path]);
    assert!(moved.status.success(), "exited with {}", moved.status);
    assert_eq!(
        String::from_utf8_lossy(&moved.stdout),
        "░░│ \n──┘ \n    \n",
        "the origin is the window's corner, so the box at (0, 0) is outside it and only the part \
         the window holds is drawn"
    );
}

/// Rule 3 — the window comes from the flags and nowhere else.
///
/// **The file says `13x9` and the command line says `6x4`, and the picture is six by four.** That
/// is the whole of the claim, and it is the one a later change is most likely to break by making the
/// marker's size optional for symmetry with the flag's: a window that could be inherited from a
/// file is a window with two sources, and the rule for which wins is the decision this change
/// removes.
///
/// The file's own window is still read and still there — the format carries it until the increment
/// that takes it out — so the assertion that matters is the one where the two disagree.
#[test]
fn the_window_comes_from_the_flags_and_nowhere_else() {
    let path = write_description(
        "two-windows",
        r#"{
            "canvas": { "origin": { "x": 0, "y": 0 }, "size": { "width": 13, "height": 9 } },
            "next_id": 2,
            "shapes": [
                { "kind": "box", "id": 1, "at": { "x": 0, "y": 0 }, "size": { "width": 4, "height": 3 },
                  "stroke": "light", "fill": "░" }
            ]
        }"#,
    );
    let path = path.to_str().expect("temp path should be valid UTF-8");

    let asked = run(&["--size", "6x4", path]);
    assert!(asked.status.success(), "exited with {}", asked.status);
    assert_eq!(
        String::from_utf8_lossy(&asked.stdout),
        "┌──┐  \n│░░│  \n└──┘  \n      \n",
        "the command line's window is the one the picture is drawn at"
    );

    let moved = run(&["--size", "6x4", "--origin", "1,1", path]);
    assert!(moved.status.success(), "exited with {}", moved.status);
    assert_eq!(
        String::from_utf8_lossy(&moved.stdout),
        "░░│   \n──┘   \n      \n      \n",
        "the origin is the window's corner, so the box at (0, 0) is outside it and only the part \
         the window holds is drawn"
    );
}

/// A flag this binary does not read prints nothing to stdout, names itself on stderr, and fails.
///
/// **The refusal is the boundary, and it is the same shape the parser's own unit tests pin.** A
/// binary that read `--width 20` as a path would draw a picture of a file that does not exist and
/// report the missing file, which is a refusal about the wrong thing.
#[test]
fn a_flag_this_binary_does_not_read_names_it_on_stderr_and_fails() {
    let output = run(&["--width", "20", "x.json"]);

    assert!(!output.status.success());
    assert!(output.stdout.is_empty(), "printed to stdout");
    let stderr = String::from_utf8_lossy(&output.stderr);
    assert!(stderr.contains("`--width` is not an option"), "{stderr}");
    assert!(stderr.contains("usage:"), "{stderr}");
}

/// A box, a line and a connector at stated positions print all three composed.
#[test]
fn a_file_with_a_box_a_line_and_a_connector_prints_all_three_composed() {
    let path = write_description(
        "three-shapes",
        r#"{
            "next_id": 4,
            "shapes": [
                { "kind": "box", "id": 1, "at": { "x": 0, "y": 0 }, "size": { "width": 4, "height": 3 },
                  "stroke": "light", "fill": "░" },
                { "kind": "line", "id": 2, "at": { "x": 0, "y": 4 }, "len": 4, "orientation": "horizontal",
                  "stroke": "light" },
                { "kind": "connector", "id": 3,
                  "from": { "at": { "kind": "point", "x": 5, "y": 0 }, "leaving": "right",
                            "terminal": { "kind": "glyph", "glyph": ">" } },
                  "to": { "at": { "kind": "point", "x": 9, "y": 2 }, "leaving": "down",
                          "terminal": { "kind": "glyph", "glyph": "v" } },
                  "stroke": "light" }
            ]
        }"#,
    );

    let output = run(&[
        "--size",
        "10x5",
        path.to_str().expect("temp path should be valid UTF-8"),
    ]);

    assert!(output.status.success(), "exited with {}", output.status);
    // Corrected on feature 099: this connector's route was a genuine tie under _The route of a
    // connector_ (fewest bends, same closeness), which feature 039 broke arbitrarily by comparing
    // waypoint coordinates. The model's own tie-break prefers the route that turns at the middle
    // of the route rectangle (x = 7), which is what this picture now pins.
    assert_eq!(
        String::from_utf8_lossy(&output.stdout),
        "┌──┐ >─┐  \n│░░│   │  \n└──┘   │ v\n       └─┘\n────      \n"
    );
    assert!(output.stderr.is_empty(), "wrote to stderr");
}

/// A box at the origin, four by three, so its right side centre is `{3, 1}`. The figure the three
/// wire cases below hang an endpoint from.
const A_BOX: &str = r#"{ "kind": "box", "id": 1, "at": { "x": 0, "y": 0 }, "size": { "width": 4, "height": 3 },
        "stroke": "light" }"#;

/// Runs a one-connector description over `at` and returns the whole of stdout, which for a path is
/// one picture and nothing else — nothing else because a picture bound for a Markdown fence cannot
/// arrive wrapped in prose, and `cargo xtask render` embeds this output in one.
///
/// `label` names the temp file, so it is the caller's short handle and not the JSON: a description
/// is full of slashes and quotes and makes for no filename at all.
fn picture_of_a_connector_hanging_from(label: &str, at: &str) -> String {
    let leaving = if at.contains(r#""kind": "point""#) {
        r#""leaving": "right","#
    } else {
        ""
    };
    let path = write_description(
        label,
        &format!(
            r#"{{
            "next_id": 3,
            "shapes": [
                {A_BOX},
                {{ "kind": "connector", "id": 2,
                  "from": {{ "at": {at}, {leaving}
                             "terminal": {{ "kind": "glyph", "glyph": ">" }} }},
                  "to": {{ "at": {{ "kind": "point", "x": 8, "y": 1 }}, "leaving": "left",
                           "terminal": {{ "kind": "arm" }} }},
                  "stroke": "light" }}
            ]
        }}"#
        ),
    );

    let output = run(&[
        "--size",
        "9x3",
        path.to_str().expect("temp path should be valid UTF-8"),
    ]);
    assert!(output.status.success(), "exited with {}", output.status);
    assert!(output.stderr.is_empty(), "wrote to stderr");
    String::from_utf8_lossy(&output.stdout).into_owned()
}

/// A file may name a side of another figure and an offset, and the picture it draws is the
/// picture the resolved point draws.
#[test]
fn a_file_naming_a_reference_draws_what_the_point_it_resolves_to_draws() {
    let named = picture_of_a_connector_hanging_from(
        "with-offset",
        r#"{ "kind": "reference", "shape": 1, "anchor": "right", "offset": { "dx": 2, "dy": 0 } }"#,
    );
    let spelled = picture_of_a_connector_hanging_from(
        "with-offset-point",
        r#"{ "kind": "point", "x": 6, "y": 1 }"#,
    );

    assert_eq!(named, spelled);
    assert!(
        !named.trim().is_empty(),
        "a reference to a box the file holds must draw the connector"
    );
}

/// A reference carrying **no** `offset` at all draws exactly what a description naming the point
/// it resolves to draws, byte for byte.
///
/// The case `{"kind": "reference", "shape": 1, "anchor": "right"}` exists for: `offset` is
/// optional and absent is zero, so a reference on the side itself is three fields rather than five,
/// and it has to draw the same thing a file spelling `{4, 1}` outright does (standing one cell
/// outward by default for a non-arm terminal).
#[test]
fn a_file_naming_a_reference_with_no_offset_draws_the_point_it_stands_on() {
    let named = picture_of_a_connector_hanging_from(
        "no-offset",
        r#"{ "kind": "reference", "shape": 1, "anchor": "right" }"#,
    );
    let spelled = picture_of_a_connector_hanging_from(
        "no-offset-point",
        r#"{ "kind": "point", "x": 4, "y": 1 }"#,
    );

    assert_eq!(named, spelled);
}

/// A file may name the gap from the side in the side's own words, and it draws the picture the
/// offset it stands for draws.
///
/// **Three routes to one cell and a fourth that is not it.** `out: 1` on a `right` side, the same
/// gap as `offset: {dx: 1, dy: 0}`, and the point `{5, 1}` spelled outright are three spellings of
/// one cell, so the comparison is not two files agreeing with each other because both were read
/// wrong. The fourth is the reference with **no gap at all**, which stands at the default gap and
/// draws something else — so the three agreeing is the field being read rather than ignored.
#[test]
fn a_file_naming_an_out_draws_the_point_the_offset_it_stands_for_draws() {
    let named = picture_of_a_connector_hanging_from(
        "with-out",
        r#"{ "kind": "reference", "shape": 1, "anchor": "right", "out": 1 }"#,
    );
    let as_an_offset = picture_of_a_connector_hanging_from(
        "with-the-offset-an-out-stands-for",
        r#"{ "kind": "reference", "shape": 1, "anchor": "right", "offset": { "dx": 1, "dy": 0 } }"#,
    );
    let outright = picture_of_a_connector_hanging_from(
        "with-the-point-an-out-reaches",
        r#"{ "kind": "point", "x": 5, "y": 1 }"#,
    );
    let at_default_gap = picture_of_a_connector_hanging_from(
        "with-no-gap",
        r#"{ "kind": "reference", "shape": 1, "anchor": "right" }"#,
    );

    assert_eq!(
        named, as_an_offset,
        "an `out` and the offset it stands for differ"
    );
    assert_eq!(named, outright, "an `out` and the point it reaches differ");
    assert_ne!(
        named, at_default_gap,
        "an `out` of one drew what a reference with no gap draws, so the field is being dropped"
    );
}

/// A file naming a shape it does not hold draws **a box and no connector at all**, and the run
/// succeeds.
///
/// This is a hole that was silent below the wire arriving through it — a position that cannot be
/// resolved is not drawn and nothing reports that it was skipped — and the offset is what makes it
/// a test rather than a comment: a large offset is the case where an implementation might clamp,
/// fall back or report, and none of the three happens. Nothing on stderr, a successful exit, and
/// the picture is the box alone.
#[test]
fn a_file_naming_a_shape_it_does_not_hold_draws_the_box_and_no_connector_and_succeeds() {
    let drawn = picture_of_a_connector_hanging_from(
        "foreign-shape",
        r#"{ "kind": "reference", "shape": 7, "anchor": "right", "offset": { "dx": 2, "dy": 0 } }"#,
    );
    let box_alone = {
        let path = write_description(
            "just-the-box",
            &format!(
                r#"{{
                "next_id": 2,
                "shapes": [ {A_BOX} ]
            }}"#
            ),
        );
        let output = run(&[
            "--size",
            "9x3",
            path.to_str().expect("temp path should be valid UTF-8"),
        ]);
        assert!(output.status.success(), "exited with {}", output.status);
        assert!(output.stderr.is_empty(), "wrote to stderr");
        String::from_utf8_lossy(&output.stdout).into_owned()
    };

    assert_eq!(
        drawn, box_alone,
        "a reference to nothing must draw the box and nothing else"
    );
}

/// The two overlapping boxes the reordering test below writes, as the `monospace_core` shapes
/// they describe, so the expected picture in each order comes from stamping them directly rather
/// than from a literal picture.
/// they describe, so the expected picture in each order comes from stamping them directly rather
/// than from a literal picture.
fn overlap_boxes() -> (monospace_core::BoxShape, monospace_core::BoxShape) {
    use monospace_core::{BoxShape, Glyph, Pos, Size, Stroke};

    (
        BoxShape {
            at: Pos { x: 0, y: 0 },
            size: Size {
                width: 4,
                height: 3,
            },
            stroke: Stroke::from("light"),
            fill: Some(Glyph::new("░").expect("\"░\" is one glyph")),
        },
        BoxShape {
            at: Pos { x: 2, y: 1 },
            size: Size {
                width: 4,
                height: 3,
            },
            stroke: Stroke::from("light"),
            fill: Some(Glyph::new("▓").expect("\"▓\" is one glyph")),
        },
    )
}

/// Renders `back` then `front`, back to front, each stamped with `StampMode::Above` — the picture
/// a description's `shapes` array in that order produces, per _The two orders are equivalent_.
fn render_back_to_front_with_above(
    back: &monospace_core::BoxShape,
    front: &monospace_core::BoxShape,
) -> String {
    use monospace_core::{
        Buffer, FigureLayer, GlyphCatalog, Pos, Shape, Size, StampMode, Window, render,
    };

    let origin = Pos { x: 0, y: 0 };
    let size = Size {
        width: 6,
        height: 4,
    };
    let mut buffer = Buffer::new(Window { origin, size });
    back.draw(&mut FigureLayer::new(&mut buffer, StampMode::Above));
    front.draw(&mut FigureLayer::new(&mut buffer, StampMode::Above));
    render(&buffer, &GlyphCatalog::light(), buffer.window())
}

/// The same file with its shapes reordered changes which one is drawn on top where they overlap
/// — the last entry in `shapes` is front-most and decides the shared cells, matching the two core
/// shapes stamped back to front with `Above`.
#[test]
fn reordering_shapes_changes_which_one_is_drawn_on_top() {
    let first = write_description(
        "overlap-a-then-b",
        r#"{
            "next_id": 3,
            "shapes": [
                { "kind": "box", "id": 1, "at": { "x": 0, "y": 0 }, "size": { "width": 4, "height": 3 },
                  "stroke": "light", "fill": "░" },
                { "kind": "box", "id": 2, "at": { "x": 2, "y": 1 }, "size": { "width": 4, "height": 3 },
                  "stroke": "light", "fill": "▓" }
            ]
        }"#,
    );
    let second = write_description(
        "overlap-b-then-a",
        r#"{
            "next_id": 3,
            "shapes": [
                { "kind": "box", "id": 1, "at": { "x": 2, "y": 1 }, "size": { "width": 4, "height": 3 },
                  "stroke": "light", "fill": "▓" },
                { "kind": "box", "id": 2, "at": { "x": 0, "y": 0 }, "size": { "width": 4, "height": 3 },
                  "stroke": "light", "fill": "░" }
            ]
        }"#,
    );

    let first_output = run(&[
        "--size",
        "6x4",
        first.to_str().expect("temp path should be valid UTF-8"),
    ]);
    let second_output = run(&[
        "--size",
        "6x4",
        second.to_str().expect("temp path should be valid UTF-8"),
    ]);

    let (a, b) = overlap_boxes();
    assert_eq!(
        String::from_utf8_lossy(&first_output.stdout),
        render_back_to_front_with_above(&a, &b)
    );
    assert_eq!(
        String::from_utf8_lossy(&second_output.stdout),
        render_back_to_front_with_above(&b, &a)
    );
    assert_ne!(first_output.stdout, second_output.stdout);
}

/// Running the same file twice produces identical output.
#[test]
fn running_the_same_file_twice_produces_identical_output() {
    let path = write_description(
        "determinism",
        r#"{
            "next_id": 2,
            "shapes": [
                { "kind": "box", "id": 1, "at": { "x": 0, "y": 0 }, "size": { "width": 4, "height": 3 },
                  "stroke": "light", "fill": "░" }
            ]
        }"#,
    );

    let first = run(&[path.to_str().expect("temp path should be valid UTF-8")]);
    let second = run(&[path.to_str().expect("temp path should be valid UTF-8")]);

    assert_eq!(first.stdout, second.stdout);
}

/// A path that does not exist prints nothing to stdout, names the path on stderr, and fails.
#[test]
fn a_missing_path_names_it_on_stderr_and_fails() {
    let path = std::env::temp_dir().join(format!(
        "monospace-cli-test-does-not-exist-{}.json",
        std::process::id()
    ));
    let _ = std::fs::remove_file(&path);

    let output = run(&[path.to_str().expect("temp path should be valid UTF-8")]);

    assert!(!output.status.success());
    assert!(output.stdout.is_empty(), "printed to stdout");
    let stderr = String::from_utf8_lossy(&output.stderr);
    assert!(
        stderr.contains(path.to_str().expect("temp path should be valid UTF-8")),
        "{stderr}"
    );
}

/// Malformed JSON prints nothing to stdout, locates the problem on stderr, and fails.
#[test]
fn malformed_json_locates_the_problem_on_stderr_and_fails() {
    let path = write_description("broken", r#"{ "canvas": "#);

    let output = run(&[path.to_str().expect("temp path should be valid UTF-8")]);

    assert!(!output.status.success());
    assert!(output.stdout.is_empty(), "printed to stdout");
    assert!(!output.stderr.is_empty(), "wrote nothing to stderr");
}

/// An unrecognized shape kind prints nothing to stdout, names the kind on stderr, and fails.
#[test]
fn an_unrecognized_kind_names_it_on_stderr_and_fails() {
    let path = write_description(
        "bad-kind",
        r#"{
            "next_id": 1,
            "shapes": [ { "kind": "triangle" } ]
        }"#,
    );

    let output = run(&[path.to_str().expect("temp path should be valid UTF-8")]);

    assert!(!output.status.success());
    assert!(output.stdout.is_empty(), "printed to stdout");
    let stderr = String::from_utf8_lossy(&output.stderr);
    assert!(stderr.contains("triangle"), "{stderr}");
}

/// Edge case: more than one command-line argument prints a usage message and fails, instead of
/// being matched on as a path.
#[test]
fn more_than_one_argument_prints_usage_and_fails() {
    let output = run(&["one.json", "two.json"]);

    assert!(!output.status.success());
    assert!(output.stdout.is_empty(), "printed to stdout");
    assert!(!output.stderr.is_empty(), "wrote nothing to stderr");
}

/// Returns the character at `(x, y)` in the first picture of `output`, treating each line as a
/// row and each `char` as a column, the same coordinates the demonstration's own window is drawn
/// at. `+ 1` skips the caption line the demonstration puts above that picture.
fn char_at(output: &str, x: usize, y: usize) -> char {
    output
        .lines()
        .nth(y + 1)
        .and_then(|line| line.chars().nth(x))
        .unwrap_or_else(|| panic!("no character at ({x}, {y}) in {output:?}"))
}

/// With no arguments, the demonstration contains both a box-drawing character (from Light) and
/// one of `+`, `-`, `|` (from ASCII).
#[test]
fn the_demonstration_contains_both_light_and_ascii_characters() {
    let output = run(&[]);
    let stdout = String::from_utf8_lossy(&output.stdout);

    assert!(
        stdout.contains(['┌', '┐', '└', '┘', '│', '─', '┬', '┴', '├', '┤', '┼']),
        "no box-drawing character in {stdout:?}"
    );
    assert!(
        stdout.contains(['+', '-', '|']),
        "no ASCII box character in {stdout:?}"
    );
}

/// At the two crossings between an ASCII figure and a Light figure added to the demo, the shared
/// cell reads from whichever figure is in front. `(28, 2)` is where
/// an ASCII box, added after a Light box already on the canvas and so front-most, shares a border
/// cell with it; `(36, 2)` is where a Light box, added after an ASCII box and so front-most,
/// shares a border cell with it.
#[test]
fn the_two_crossings_read_from_whichever_figure_is_in_front() {
    let output = run(&[]);
    let stdout = String::from_utf8_lossy(&output.stdout);

    let ascii_in_front = char_at(&stdout, 28, 2);
    assert!(
        matches!(ascii_in_front, '+' | '-' | '|'),
        "expected an ASCII character at (28, 2), got {ascii_in_front:?}"
    );

    let light_in_front = char_at(&stdout, 36, 2);
    assert_eq!(
        light_in_front, '┼',
        "expected the Light crossing character at (36, 2)"
    );
}

/// Feature 056 follow-up: the demonstration also contains a box drawn with each of Double, Heavy
/// and Light Round, so a no-argument run shows all five built-in tables at once.
#[test]
fn the_demonstration_contains_double_heavy_and_light_round_characters() {
    let output = run(&[]);
    let stdout = String::from_utf8_lossy(&output.stdout);

    assert!(
        stdout.contains(['║', '╗', '╦', '╬', '╣', '╔', '╠', '═', '╩', '╝', '╚']),
        "no Double box character in {stdout:?}"
    );
    assert!(
        stdout.contains(['┃', '┓', '┳', '╋', '┫', '┏', '┣', '━', '┻', '┛', '┗']),
        "no Heavy box character in {stdout:?}"
    );
    assert!(
        stdout.contains(['╮', '╭', '╯', '╰']),
        "no Light Round corner character in {stdout:?}"
    );
}

/// Each pair of overlapping boxes below the original demonstration crosses two single-stroke
/// tables. Feature 060 loads mixing tables for two of the six pairs here — Light with Double and
/// Light with Heavy — so their crossing now draws the character the exact mixed arms produce
/// instead of degrading. The other two pairs (Light Round with Light, Double with Heavy) still
/// have no mixing table pairing them, so they still degrade every connected arm to the one base
/// stroke — the stroke of the figure that last claimed the cell, which is what makes the answer to
/// "why that character?" a single sentence, and whichever figure is added last since it is
/// front-most and decides first.
/// Each crossing cell below is the same position the original two crossings use: where the first
/// box's bottom border meets the second box's left side.
#[test]
fn crossings_between_the_new_tables_mix_or_degrade_depending_on_table_coverage() {
    let output = run(&[]);
    let stdout = String::from_utf8_lossy(&output.stdout);

    for (x, y, expected, label) in [
        (
            2,
            11,
            '╫',
            "Double in front of Light: covered by Light/Double, mixes instead of degrading",
        ),
        (
            10,
            11,
            '╪',
            "Light in front of Double: covered by Light/Double, mixes instead of degrading",
        ),
        (
            18,
            11,
            '╂',
            "Heavy in front of Light: covered by Light/Heavy, mixes instead of degrading",
        ),
        (
            26,
            11,
            '┿',
            "Light in front of Heavy: covered by Light/Heavy, mixes instead of degrading",
        ),
        (
            34,
            11,
            '┼',
            "Light Round in front of Light: no mixing table pairs them, still degrades",
        ),
        (
            42,
            11,
            '╬',
            "Double in front of Heavy: no mixing table pairs them, still degrades",
        ),
    ] {
        let ch = char_at(&stdout, x, y);
        assert_eq!(ch, expected, "{label}: expected {expected:?} at ({x}, {y})");
    }
}

/// Rule 8 — `--symbols` prints one row per style `all()` reports, in name order, each name padded
/// to the longest and one space, then one cell per symbol.
///
/// **A miss is a space and the row keeps it**, which is what makes the four pointer styles' rows end
/// in three spaces while `ascii`'s two gaps sit before its circle.
#[test]
fn symbols_prints_a_row_per_style_in_name_order_with_a_space_for_a_miss() {
    let output = run(&["--symbols"]);

    assert!(output.status.success(), "the sheet is a run");
    assert!(output.stderr.is_empty(), "wrote to stderr");

    let expected = concat!(
        "arrow         ↑→↓←   \n",
        "ascii         ^>v<  o\n",
        "outline       △▷▽◁◇⬡○\n",
        "small-outline ▵▹▿◃   \n",
        "small-solid   ▴▸▾◂   \n",
        "solid         ▲▶▼◀◆⬢●\n",
        "solid-pointer ▲►▼◄   \n",
    );

    assert_eq!(String::from_utf8_lossy(&output.stdout), expected);
}

/// Rule 9 — the sheet takes nothing else, so a path or a window beside it is refused by name, and
/// the usage line lists `--symbols` as a form of its own.
#[test]
fn symbols_refuses_a_path_and_a_window_and_the_usage_line_names_it() {
    for (args, said) in [
        (
            &["--symbols", "x.json"][..],
            "`x.json` cannot be given beside `--symbols`",
        ),
        (
            &["--size", "4x3", "--symbols"][..],
            "`--size` cannot be given beside `--symbols`",
        ),
        (
            &["--origin", "0,0", "--symbols"][..],
            "`--origin` cannot be given beside `--symbols`",
        ),
        (
            &["--symbols", "--symbols"][..],
            "`--symbols` was given twice",
        ),
    ] {
        let output = run(args);

        assert!(
            !output.status.success(),
            "{args:?} should have been refused"
        );
        assert!(output.stdout.is_empty(), "{args:?} printed to stdout");
        let stderr = String::from_utf8_lossy(&output.stderr);
        assert!(stderr.contains(said), "{args:?}: {stderr}");
        assert!(
            stderr.contains("monospace-cli --symbols"),
            "{args:?}: the usage line names the sheet: {stderr}"
        );
    }
}