JoshHeaps.Net/tests/holdem/betChips.test.js

// Where a player's bet sits on the felt.
//
// The chips were the last thing on the table nobody had measured. They were laid out on
// a ring of their own at a fixed 27/44 of the seat's reach — a fraction picked when the
// seat ring was itself fixed — and the choice between that ring and clinging to the
// puck was made by asking how wide the *window* was. Neither of those is a question
// about the felt. A phone held sideways is 844px across and gives the felt 117px of
// height: it passed the width test, took the ring, and every chip on it was painted
// behind a seat. The seats carry `z-index: 1` and the bets layer carries none, so a
// chip under a puck is not dimmed or half-hidden — it is gone, and with it the only
// number saying what that player has in.
//
// Everything below is geometry, so it runs without a browser. The felts are the ones
// measured on real screens: 692x117 is a phone on its side, 300x216 a phone upright.
const test = require("node:test");
const { describe } = require("node:test");
const assert = require("node:assert");
const { Render } = require("./load");

const RADII = { rx: 44, ry: 42 };
const PUCK = { width: 96, height: 64 };
const CHIP = { width: 44, height: 22 };

const felt = (width, height) => ({ width, height });
const spacingOn = (box, puck = PUCK, chip = CHIP) =>
    ({ box, puck, chip, clearance: Render.BET_CLEARANCE_PX });

// A chip's centre in pixels on a given felt.
const chipPixels = (index, count, box, spacing, radii = RADII) => {
    const pos = Render.betPosition(index, count, box.width / box.height, radii, spacing);
    return { x: (pos.left / 100) * box.width, y: (pos.top / 100) * box.height };
};

const seatPixels = (index, count, box, radii = RADII) => {
    const pos = Render.seatPosition(index, count, box.width / box.height, radii);
    return { x: (pos.left / 100) * box.width, y: (pos.top / 100) * box.height };
};

// Two axis-aligned boxes, by their centres. The same test the seats settle among
// themselves — see seatFootprint.test.js — because it is the same question.
const boxesOverlap = (a, b, sizeA, sizeB) =>
    Math.abs(a.x - b.x) < (sizeA.width + sizeB.width) / 2 - 0.5 &&
    Math.abs(a.y - b.y) < (sizeA.height + sizeB.height) / 2 - 0.5;

describe("reaching the edge of a box", () => {
    test("straight out the side is half the width, straight up half the height", () => {
        assert.equal(Render.edgeReach(96, 64, 1, 0), 48);
        assert.equal(Render.edgeReach(96, 64, 0, -1), 32);
        assert.equal(Render.edgeReach(96, 64, -1, 0), 48);
    });

    test("a corner is whichever edge the ray meets first", () => {
        // 45° out of a 96x64 box: the top and bottom are nearer than the sides, so the
        // ray leaves through one of those. A single radius — half the diagonal, 57.7 —
        // would put a chip 25px further out than it needs to be, which on a 117px felt
        // is the difference between clear of the puck and off the table.
        const diagonal = Render.edgeReach(96, 64, Math.SQRT1_2, Math.SQRT1_2);
        assert.ok(Math.abs(diagonal - 32 / Math.SQRT1_2) < 1e-9, `got ${diagonal}`);
        assert.ok(diagonal < 48, "and never further than the wider half-edge");
    });

    test("a square is the same in every direction it is asked about", () => {
        const straight = Render.edgeReach(50, 50, 0, 1);
        assert.equal(Render.edgeReach(50, 50, 1, 0), straight);
    });
});

describe("getting one box clear of another", () => {
    const PUCK96 = { width: 96, height: 88 };
    const CHIP50 = { width: 50, height: 21 };

    // Travel `t` along `u` from the puck's centre, then ask whether the two boxes are
    // apart. This is the question clearanceReach is supposed to answer, asked the long
    // way round so the answer can be checked rather than restated.
    const apart = (t, ux, uy) =>
        Math.abs(t * ux) >= (PUCK96.width + CHIP50.width) / 2 - 1e-9 ||
        Math.abs(t * uy) >= (PUCK96.height + CHIP50.height) / 2 - 1e-9;

    test("straight up and down it is what adding the two half-heights gives", () => {
        assert.equal(Render.clearanceReach(PUCK96, CHIP50, 0, -1), (88 + 21) / 2);
        assert.equal(Render.clearanceReach(PUCK96, CHIP50, 1, 0), (96 + 50) / 2);
    });

    test("on a diagonal it is more than the two reaches added together", () => {
        // The bug this replaced. Two axis-aligned boxes are clear when they are apart on
        // one axis, and the travel that achieves that is the reach of the box you get by
        // adding their widths and their heights — which is never less, and on a diagonal
        // is more, than adding the two boxes' own reaches. At 768x1024 the difference was
        // 11px, and 11px is how far inside its own player's puck the chip came to rest.
        const dirs = [[0.83, 0.56], [0.6, 0.8], [0.9, 0.44], [Math.SQRT1_2, Math.SQRT1_2]];
        let shortfalls = 0;
        dirs.forEach(([ux, uy]) => {
            const summed = Render.edgeReach(PUCK96.width, PUCK96.height, ux, uy) +
                Render.edgeReach(CHIP50.width, CHIP50.height, ux, uy);
            const proper = Render.clearanceReach(PUCK96, CHIP50, ux, uy);
            assert.ok(proper >= summed - 1e-9, `${ux},${uy}: ${proper} < ${summed}`);
            if (proper <= summed + 1e-9) return;
            // Where they differ, the old answer was not merely smaller — it was wrong:
            // travelling that far leaves the two boxes still on top of each other.
            shortfalls++;
            assert.ok(!apart(summed, ux, uy),
                `${ux},${uy}: adding the reaches gave ${summed.toFixed(1)}, which is enough after all`);
        });
        assert.ok(shortfalls >= 2, "expected the two to actually differ on some of these");
    });

    test("and it is exactly enough — a hair less is not", () => {
        const dirs = [[0, -1], [1, 0], [0.83, 0.56], [0.6, -0.8], [-0.9, 0.44]];
        dirs.forEach(([ux, uy]) => {
            const t = Render.clearanceReach(PUCK96, CHIP50, ux, uy);
            assert.ok(apart(t, ux, uy), `${ux},${uy}: ${t}px still overlaps`);
            assert.ok(!apart(t - 0.5, ux, uy), `${ux},${uy}: ${t}px is further than needed`);
        });
    });
});

describe("a chip on the ring", () => {
    test("with nothing measured it keeps the proportions the ring always used", () => {
        // The unit suite and the very first render both call it this way. 27/44 and
        // 25/42 of the seat's own reach, so the chips move with the ring rather than
        // with the felt.
        const seat = Render.seatPosition(3, 9, 1.4, RADII);
        const chip = Render.betPosition(3, 9, 1.4, RADII, null);
        assert.ok(Math.abs((chip.left - 50) - (seat.left - 50) * (27 / 44)) < 1e-9);
        assert.ok(Math.abs((chip.top - 50) - (seat.top - 50) * (25 / 42)) < 1e-9);
    });

    test("measured, it sits just clear of its own puck rather than at a fixed fraction", () => {
        const box = felt(560, 400);
        const spacing = spacingOn(box);
        for (let i = 0; i < 9; i++) {
            const seat = seatPixels(i, 9, box);
            const chip = chipPixels(i, 9, box, spacing);
            assert.ok(!boxesOverlap(seat, chip, PUCK, CHIP),
                `seat ${i + 1}'s own chip is under its own puck`);
        }
    });

    test("and never wanders into the pot badge in the middle", () => {
        // The floor: 38% of the way out. Without it a chip walked in past a puck that
        // is 96px wide on a felt whose reach is 90px would land on the pot total, which
        // is the same fault at the other end of the spoke.
        const box = felt(300, 216);
        const spacing = spacingOn(box, { width: 200, height: 150 });
        for (let i = 0; i < 6; i++) {
            const seat = seatPixels(i, 6, box);
            const chip = chipPixels(i, 6, box, spacing);
            const seatReach = Math.hypot(seat.x - box.width / 2, seat.y - box.height / 2);
            const chipReach = Math.hypot(chip.x - box.width / 2, chip.y - box.height / 2);
            assert.ok(chipReach >= seatReach * 0.38 - 0.5,
                `chip ${i + 1} is ${chipReach.toFixed(1)}px out of a possible ${seatReach.toFixed(1)}`);
        }
    });

    test("a seat sitting dead centre gets its chip put somewhere, not NaN", () => {
        const box = felt(400, 300);
        const pos = Render.betPosition(0, 1, box.width / box.height, { rx: 0, ry: 0 }, spacingOn(box));
        assert.ok(Number.isFinite(pos.left) && Number.isFinite(pos.top), JSON.stringify(pos));
    });
});

describe("deciding whether a ring of chips fits at all", () => {
    // The shape the layout works in: one entry per chip on the felt, carrying its own
    // measured size, because a chip is as wide as the number printed on it.
    const tableOf = (count, chip = CHIP) => {
        Render.state = { seatCount: count, seats: Array.from({ length: count }, () => ({})) };
        return Array.from({ length: count }, (_, i) =>
            ({ index: i, width: chip.width, height: chip.height }));
    };

    test("a desktop felt has room for one", () => {
        const box = felt(700, 500);
        const all = tableOf(9);
        assert.equal(Render.chipsClearTheSeats(all, box.width / box.height, RADII, spacingOn(box)), true);
    });

    test("a phone on its side has not, whatever the window's width says about it", () => {
        // 692x117, measured on an 844px-wide phone in landscape — a viewport that sails
        // past a `max-width: 700px` test. The ring is a slot: the 38% floor puts a chip
        // on the seat across the table from it.
        const box = felt(692, 117);
        const all = tableOf(9);
        assert.equal(Render.chipsClearTheSeats(all, box.width / box.height, RADII, spacingOn(box)), false,
            "this is the felt where every chip was painted behind a puck");
    });

    test("its answer is the one the geometry gives", () => {
        // Not a restatement of the two cases above: whatever it returns, it has to agree
        // with laying the chips out and measuring them against every puck on the felt.
        const shapes = [felt(700, 500), felt(692, 117), felt(300, 216), felt(1000, 620), felt(480, 300)];
        shapes.forEach(box => {
            const all = tableOf(9);
            const spacing = spacingOn(box);
            const aspect = box.width / box.height;
            const clear = all.every(({ index: i }) => {
                const chip = chipPixels(i, 9, box, spacing);
                return all.every(({ index: j }) => !boxesOverlap(chip, seatPixels(j, 9, box), CHIP, PUCK));
            });
            assert.equal(Render.chipsClearTheSeats(all, aspect, RADII, spacing), clear,
                `${box.width}x${box.height}`);
        });
    });

    test("each chip is asked about at its own size", () => {
        // A chip is as wide as the number on it: at 768x1024, four players' chips were
        // 40px and one holding a four-figure bet was 47. Answering the question once, at
        // the widest, told the whole felt it had no room for a ring — and dropped all
        // five chips onto their own players' stacks to solve a problem four of them
        // did not have.
        // The felt and the pucks are the iPad's own, measured: 672x672, pucks 96x88.
        const box = felt(672, 672);
        const narrow = { width: 40, height: 20 };
        const huge = { width: 420, height: 380 };
        const spacing = { box, puck: { width: 96, height: 88 }, clearance: Render.BET_CLEARANCE_PX };
        const aspect = box.width / box.height;

        assert.equal(Render.chipsClearTheSeats(tableOf(9, narrow), aspect, RADII, spacing), true,
            "a felt this size has room for a ring of ordinary chips");
        assert.equal(Render.chipsClearTheSeats(tableOf(9, huge), aspect, RADII, spacing), false,
            "and none at all for a ring of chips that size");

        // Now one of each. The answer has to come from the sizes in the list, not from
        // one size standing in for all of them: with one huge chip the ring is off, and
        // taking that chip out of the question puts it back.
        const mixed = tableOf(9, narrow);
        mixed[0] = { index: 0, ...huge };
        assert.equal(Render.chipsClearTheSeats(mixed, aspect, RADII, spacing), false);
        assert.equal(Render.chipsClearTheSeats(mixed.slice(1), aspect, RADII, spacing), true,
            "the eight ordinary ones were never the problem");
    });

    test("and at the chips against each other", () => {
        // The ring is a smaller circle than the seats' one and holds the same number of
        // things, so it is the tighter fit of the two. Measured on a Pixel 7 with twelve
        // players, two $10s on the ring sat on top of each other while every puck on the
        // felt was clear — so a check that only looks at the pucks says yes to a layout
        // that hides one player's bet behind another's.
        // The Pixel 7's own numbers, measured: a 300x336 felt on a ring of 44 by 40.84,
        // pucks 44x55, a pot badge 64x53, and the seven players who had put chips in.
        const box = felt(300, 336);
        const radii = { rx: 44, ry: 40.84 };
        const puck = { width: 44, height: 55 };
        const pot = { x: 150, y: 168, width: 64, height: 53 };
        const spacing = { box, puck, pot, clearance: Render.BET_CLEARANCE_PX };
        const aspect = box.width / box.height;

        Render.state = { seatCount: 12, seats: Array.from({ length: 12 }, () => ({})) };
        const bettors = [2, 3, 4, 5, 6, 7, 8];
        const all = bettors.map(index => ({ index, width: index === 2 ? 44.1 : 49.7, height: 21 }));

        const chips = all.map(entry => ({
            ...entry,
            ...chipPixels(entry.index, 12, box,
                { ...spacing, chip: { width: entry.width, height: entry.height } }, radii),
        }));
        const seats = [...Array(12).keys()].map(i => seatPixels(i, 12, box, radii));

        assert.equal(chips.some(chip => seats.some(seat => boxesOverlap(chip, seat, chip, puck))), false,
            "this table is chosen so the pucks are not the problem");
        assert.equal(chips.some(chip => boxesOverlap(chip, pot, chip, pot)), false,
            "nor the pot");
        assert.ok(chips.some((chip, i) => chips.some((other, j) => i !== j &&
            boxesOverlap(chip, other, chip, other))), "and so the chips are");

        assert.equal(Render.chipsClearTheSeats(all, aspect, radii, spacing), false);
    });

    test("it looks at every puck, not just the chip's own", () => {
        // The rule this replaced walked each chip in until it was clear of its *own*
        // seat and stopped there, which says nothing about the eight other pucks on the
        // felt. 560x190 is a felt where that rule is satisfied and the ring is still no
        // good: every chip clears the puck it belongs to, and one of them is sitting on
        // a stranger's.
        const box = felt(560, 190);
        const all = tableOf(9);
        const spacing = spacingOn(box);
        const chips = all.map(({ index: i }) => chipPixels(i, 9, box, spacing));

        all.forEach(({ index: i }) => assert.ok(!boxesOverlap(chips[i], seatPixels(i, 9, box), CHIP, PUCK),
            `chip ${i + 1} is under its own puck, so this felt does not make the point`));
        assert.ok(all.some(({ index: i }) => all.some(({ index: j }) => i !== j &&
                boxesOverlap(chips[i], seatPixels(j, 9, box), CHIP, PUCK))),
            "expected a chip on somebody else's puck — what the old rule could not see");
        assert.equal(Render.chipsClearTheSeats(all, box.width / box.height, RADII, spacing), false);
    });
});

describe("a chip clinging to its puck", () => {
    // The fallback when there is no room for a ring: the chip hangs off the puck on the
    // side facing the empty middle of the felt.
    //
    // The felts the app actually draws, with the puck size each one settles on — read
    // off the running site at each viewport rather than guessed here, because the tight
    // felts shrink the puck too, and a test that holds the desktop's 96x64 puck against
    // a 528x83 felt is describing a table the app never draws.
    const REAL = [
        ["Galaxy S8 on its side", felt(528, 83), { width: 44, height: 55 }],
        ["iPhone on its side", felt(692, 113), { width: 72, height: 55 }],
        ["Galaxy S8 upright, six-handed", felt(248, 280), { width: 78, height: 88 }],
        ["Galaxy S8 upright, packed", felt(248, 280), { width: 44, height: 55 }],
    ];
    // Chips are 21x17 everywhere they are anchored — the amount is the only thing on
    // one at that size.
    const TIGHT = { puck: { width: 44, height: 55 }, chip: { width: 21, height: 17 } };

    // What each chip is told to do, worked out for the whole table at once.
    const placeAll = (count, box, puck, chip = TIGHT.chip, radii = RADII) => {
        Render.state = { seatCount: count, seats: Array.from({ length: count }, () => ({})) };
        const indices = [...Array(count).keys()];
        const entries = indices.map(i => ({ index: i, width: chip.width, height: chip.height }));
        const spacing = { box, puck, clearance: Render.BET_CLEARANCE_PX };
        const offs = Render.anchoredChipTravel(entries, count, box.width / box.height, RADII, spacing);
        return indices.map(i => {
            const seat = Render.seatPosition(i, count, box.width / box.height, radii);
            const at = { x: (seat.left / 100) * box.width, y: (seat.top / 100) * box.height };
            const off = offs[i];
            return { seat: at, chip: { x: at.x + off.x, y: at.y + off.y }, off, puck };
        });
    };

    test("on its own, a chip asks to sit just clear of its puck", () => {
        const box = felt(692, 113);
        const puck = { width: 72, height: 55 };
        const seat = Render.seatPosition(0, 9, box.width / box.height, RADII);
        const off = Render.anchoredChipOffset(seat, puck, TIGHT.chip, box, RADII);
        const travel = Math.hypot(off.x, off.y);
        const ux = off.x / travel, uy = off.y / travel;
        assert.ok(Math.abs(travel -
            (Render.clearanceReach(puck, TIGHT.chip, ux, uy) + Render.BET_CLEARANCE_PX)) < 1e-6, `travelled ${travel}`);
    });

    test("and gets it, where nothing else is in the way", () => {
        // 692x113 is the roomier of the two landscape felts. Every chip clears its own
        // puck and none of them has to give ground.
        placeAll(9, felt(692, 113), { width: 72, height: 55 }).forEach((row, i) => {
            assert.ok(!boxesOverlap(row.seat, row.chip, row.puck, TIGHT.chip),
                `seat ${i + 1}'s chip is inside its own puck, and nothing made it go there`);
        });
    });

    test("it goes off the rim, not down the spoke", () => {
        // On a felt 692x113 the two are nowhere near the same direction. A seat on the
        // top rail has a spoke pointing diagonally inward — which along a slot this flat
        // runs sideways into the next seat — while off the rim is very nearly straight
        // down, into the empty middle. This is the seam that put two chips on top of
        // each other on a Galaxy S8.
        const box = felt(692, 113);
        const rows = placeAll(9, box, { width: 72, height: 55 });
        const top = rows.find(r => r.seat.y < box.height * 0.3 && r.seat.x > box.width * 0.7);
        assert.ok(top, "expected a seat up on the right of the top rail");
        assert.ok(Math.abs(top.off.y) > Math.abs(top.off.x) * 2,
            `chip went ${top.off.x.toFixed(1)},${top.off.y.toFixed(1)} — that is along the rail, not off it`);
        assert.ok(top.off.y > 0, "and downward, toward the middle of the felt");
    });

    test("no two chips on a full table land on each other", () => {
        // Four sides gave three seams. There are no sides now, and this is what that is
        // worth — on every felt the app actually draws, at every table size.
        REAL.forEach(([name, box, puck]) => {
            [6, 9, 12].forEach(count => {
                const rows = placeAll(count, box, puck);
                for (let a = 0; a < rows.length; a++) {
                    for (let b = a + 1; b < rows.length; b++) {
                        assert.ok(!boxesOverlap(rows[a].chip, rows[b].chip, TIGHT.chip, TIGHT.chip),
                            `${name}, ${count} seats: chips ${a + 1} and ${b + 1} overlap`);
                    }
                }
            });
        });
    });

    test("a chip only gives ground when it is standing on something", () => {
        // The point of pulling chips back one at a time rather than by a rule that
        // applies to all of them. Stopping every chip at the felt's midline, or scaling
        // them all by one factor, takes travel from the seats at the ends of a long
        // rail — measured at 692x113, that parked two chips on their own player's stack
        // to solve a collision that did not exist.
        //
        // So: every chip either got everything it asked for, or putting the last step
        // back reintroduces a collision it is part of. The step goes back for all of
        // them at once, because a facing pair gives ground together and the pass that
        // finally separates such a pair moves both ends of it.
        const step = Render.CHIP_PULLBACK_STEP_PX;
        REAL.forEach(([name, box, puck]) => {
            [6, 9, 12].forEach(count => {
                const rows = placeAll(count, box, puck).map(row => {
                    const travel = Math.hypot(row.off.x, row.off.y);
                    const dir = travel < 1e-6 ? { x: 0, y: 0 } : { x: row.off.x / travel, y: row.off.y / travel };
                    const asked = travel < 1e-6 ? 0 :
                        Render.clearanceReach(puck, TIGHT.chip, dir.x, dir.y) +
                        Render.BET_CLEARANCE_PX;
                    const back = Math.min(asked, travel + step);
                    return { ...row, travel, asked,
                        undone: { x: row.seat.x + dir.x * back, y: row.seat.y + dir.y * back } };
                });

                rows.forEach((row, i) => {
                    if (row.travel < 1e-6 || row.travel >= row.asked - 1e-6) return;
                    const onSomething = rows.some((other, j) => j !== i && (
                        boxesOverlap(row.undone, other.undone, TIGHT.chip, TIGHT.chip) ||
                        boxesOverlap(row.undone, other.seat, TIGHT.chip, puck)));
                    assert.ok(onSomething,
                        `${name}, ${count} seats: chip ${i + 1} stopped ${(row.asked - row.travel).toFixed(1)}px short of nothing`);
                });
            });
        });
    });

    test("nobody is pushed further out than they asked to go", () => {
        // The pull-back only ever takes travel away. A chip pushed past its clearance
        // would be floating out on the felt with nothing to say whose it is.
        REAL.forEach(([name, box, puck]) => {
            placeAll(12, box, puck).forEach((row, i) => {
                const travel = Math.hypot(row.off.x, row.off.y);
                if (travel < 1e-6) return;
                const ux = row.off.x / travel, uy = row.off.y / travel;
                const asked = Render.clearanceReach(puck, TIGHT.chip, ux, uy) +
                    Render.BET_CLEARANCE_PX;
                assert.ok(travel <= asked + 0.5,
                    `${name}: chip ${i + 1} went ${travel.toFixed(1)}px when ${asked.toFixed(1)} was asked for`);
            });
        });
    });

    test("the direction turns smoothly all the way round the ring", () => {
        // The property a set of discrete sides cannot have, and the reason there are
        // none: neighbouring seats get neighbouring directions, with no step anywhere.
        const box = felt(560, 400);
        const angles = Array.from({ length: 24 }, (_, i) => {
            const seat = Render.seatPosition(i, 24, box.width / box.height, RADII);
            const off = Render.anchoredChipOffset(seat, PUCK, CHIP, box, RADII);
            return Math.atan2(off.y, off.x);
        });
        angles.forEach((angle, i) => {
            const next = angles[(i + 1) % angles.length];
            let turn = Math.abs(next - angle);
            if (turn > Math.PI) turn = 2 * Math.PI - turn;
            assert.ok(turn < Math.PI / 4,
                `between seats ${i + 1} and ${i + 2} the chip jumps ${(turn * 180 / Math.PI).toFixed(0)}°`);
        });
    });

    test("it stops short of the pot total as well", () => {
        // The other thing in the middle of the felt, and the one number on the table
        // that belongs to everybody. A seat on the middle of a rail sends its chip
        // straight at it: on a Galaxy S8 on its side, seat 1's $10 was sitting on
        // "Pot $65". The badge is measured rather than assumed to be at the centre —
        // it lives on the table, not on either overlay, and the two are not concentric.
        const box = felt(528, 83);
        const pot = { x: 264, y: 40, width: 96, height: 34 };
        Render.state = { seatCount: 12, seats: Array.from({ length: 12 }, () => ({})) };
        const indices = [...Array(12).keys()];
        const entries = indices.map(i =>
            ({ index: i, width: TIGHT.chip.width, height: TIGHT.chip.height }));
        const spacing = { box, puck: TIGHT.puck, clearance: Render.BET_CLEARANCE_PX, pot };
        const offs = Render.anchoredChipTravel(entries, 12, box.width / box.height, RADII, spacing);

        indices.forEach(i => {
            const seat = Render.seatPosition(i, 12, box.width / box.height, RADII);
            const chip = { x: (seat.left / 100) * box.width + offs[i].x,
                           y: (seat.top / 100) * box.height + offs[i].y };
            assert.ok(!boxesOverlap(chip, pot, TIGHT.chip, pot),
                `chip ${i + 1} is on the pot total`);
        });
    });

    test("a seat with no rim to be off still gets an answer", () => {
        const box = felt(400, 300);
        const off = Render.anchoredChipOffset({ left: 50, top: 50 }, PUCK, CHIP, box, RADII);
        assert.ok(Number.isFinite(off.x) && Number.isFinite(off.y), JSON.stringify(off));
        assert.ok(off.y < 0, "upward, which is where a puck's own writing is not");
    });
});