[READ-ONLY] Mirror of https://github.com/bombshell-dev/tty. Platform independent 2D layout engine for terminal applications based on Clay
test: failing repro for signed-margin
Nate Moore
(Jun 4, 2026, 12:32 AM -0500)
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test/signed-margin.test.ts
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test/signed-margin.test.ts
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import { describe, expect, it } from "./suite.ts";
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import { createTerm } from "../term.ts";
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import { close, fixed, grow, open, type OpenElement, text } from "../ops.ts";
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import { print } from "./print.ts";
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const decode = (b: Uint8Array) => new TextDecoder().decode(b);
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// Proposed (not-yet-implemented) signed offset prop. Cast through this so the
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// ops still type-check while `margin` is silently ignored by the current build.
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type Margin = { left?: number; right?: number; top?: number; bottom?: number };
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const withMargin = (
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layout: NonNullable<OpenElement["layout"]>,
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margin: Margin,
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): NonNullable<OpenElement["layout"]> =>
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({ ...layout, margin }) as NonNullable<OpenElement["layout"]>;
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describe("layout margin (signed offset)", () => {
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it("positive marginLeft shifts the box origin without shrinking content", async () => {
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let term = await createTerm({ width: 20, height: 4 });
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let r = term.render([
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open("root", {
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layout: { width: grow(), height: grow(), direction: "ttb" },
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}),
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open("box", {
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layout: withMargin({ width: fixed(8), direction: "ttb" }, { left: 2 }),
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}),
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text("Hello W"),
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close(),
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close(),
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]);
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// pins: box origin moves right by 2 cells (margin offsets position, not content)
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expect(r.info.get("box")!.bounds.x).toBe(2);
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// pins: full 7-cell text still fits on ONE line (margin must not consume width)
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expect(r.info.get("box")!.bounds.height).toBe(1);
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});
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it("negative marginLeft pulls the box before the parent origin and clips", async () => {
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let term = await createTerm({ width: 20, height: 4 });
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let r = term.render([
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open("root", {
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layout: { width: fixed(6), height: grow(), direction: "ttb" },
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clip: { horizontal: true },
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}),
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open("box", {
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layout: withMargin(
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{ width: fixed(12), direction: "ttb" },
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{ left: -3 },
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),
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}),
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text("Hello World"),
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close(),
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close(),
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]);
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let first = print(decode(r.output), 20, 4).split("\n")[0];
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// pins: leftmost 3 cells fall outside the parent and are clipped away
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expect(first.slice(0, 6)).toBe("lo Wor");
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});
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it("negative margin keeps box geometry sane (no unsigned overflow)", async () => {
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let term = await createTerm({ width: 20, height: 6 });
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let r = term.render([
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open("root", {
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layout: { width: grow(), height: grow(), direction: "ttb" },
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}),
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open("box", {
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layout: withMargin(
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{ width: fixed(11), direction: "ttb" },
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{ left: -3 },
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),
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}),
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text("Hello World"),
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close(),
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close(),
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]);
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// pins: the box origin is pulled left by 3 cells (negative offset is signed)
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expect(r.info.get("box")!.bounds.x).toBe(-3);
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});
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});