`fixtures/fixtures.ts` — canonical regression grids

(no submodules)

Purpose

This module is the canonical test-fixture surface for the package. Each exported function returns a deterministic RGBA[] grid with known algorithmic properties — chessboards, donuts, crosses, T-shapes, stars, flags, shields, and crests. Together they form the regression suite that locks the solver's quality numbers in place: any change that regresses the rect count on one of these fixtures fails the test gate.

Features

Twelve fixtures total: chessboard8x8, cross3x3, cross6x6, tShape, donut5x5, circle16, flagCrosses, multiIslandStripes, shieldEmblem32, crest12x12, star, plus the added nineColours (>8 distinct colours, used to exercise the auto-ordering heuristic branch).
Every fixture is purely declarative — built from a number[][] palette index map and fromIndexedGrid. No randomness, no Date.now, no module-load side effects.
Index 0 is reserved for transparency; every fixture follows that convention.

Usage: Basic

import { chessboard8x8 } from "@suaveplan/emblem-solver";

const { pixels, width, height } = chessboard8x8();

Usage: Advanced

import { convert, crest12x12 } from "@suaveplan/emblem-solver";

const { pixels, width, height } = crest12x12();
const result = convert(pixels, width, height, { layerOrder: "auto" });
console.log(`crest compressed to ${result.totalRects} rects`);

API Reference

Symbol	Returns
`chessboard8x8()`	8x8 alternating black/white grid
`cross3x3()` / `cross6x6()`	Plus-sign crosses
`tShape()`	5x4 T-shape
`donut5x5()`	Frame with transparent centre
`circle16()`	16-px pixel circle
`flagCrosses()`	16x16 layered three-colour flag
`multiIslandStripes()`	10x2 alternating two-colour stripes
`shieldEmblem32()`	32x32 three-colour shield
`crest12x12()`	12x12 four-colour crest
`star()`	Irregular star outline
`nineColours()`	4x4 grid with nine distinct colours

Implementation Notes

The fixtures are exported as zero-argument functions rather than constants so each test call builds a fresh pixel array — the solver does not mutate its input, but defensive copies keep test isolation strong. The nineColours grid exists specifically to push factorial(colourCount) > maxPermutations so the heuristic + sampling branch in convert() is exercised; without it that branch would be unreachable and coverage would drop. Fixtures are excluded from the package's coverage threshold (coverage.exclude in vitest.config.ts) because they are test material, not production code.

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fixtures/fixtures.ts — canonical regression grids