feedBack/tests/js/highway_chord_render_cache.test.js

// Source-level guards for the 2D highway chord render cache
// (`_ensureChordRenderCache`). Locks in the invalidation contract so a
// regression that drops one of the three keys, or forgets to reset the
// derived state, will fail in CI.
//
// Background: see feedBack#412 and the Copilot review thread that
// surfaced the `chordTemplates` ordering edge case (templates can land
// after the final `chords` chunk; `isOpen()`-derived `nonZeroNotes`
// would otherwise stay stale until the next chord transition).
//
// Like the other highway tests in this directory, these inspect the
// source rather than executing — the createHighway() closure owns
// canvas + WebGL lifecycle that's too heavy for a vm sandbox.

const { test } = require('node:test');
const assert = require('node:assert/strict');
const fs = require('node:fs');
const path = require('node:path');

const highwayJs = path.join(__dirname, '..', '..', 'static', 'highway.js');

test('_ensureChordRenderCache keys off src, _inverted, AND chordTemplates', () => {
    const src = fs.readFileSync(highwayJs, 'utf8');
    // The cache key triple must include chordTemplates — without it, a
    // late-arriving `chord_templates` WS message leaves cached
    // nonZeroNotes / nonZeroFrets stale until the next chord transition.
    //
    // Match either operand order (`A === B` or `B === A`) so a future
    // stylistic refactor that flips sides doesn't trip these guards —
    // the semantic invariant is the comparison, not its placement.
    const eqEither = (a, b) => new RegExp(
        `\\b${a}\\b\\s*===\\s*\\b${b}\\b|\\b${b}\\b\\s*===\\s*\\b${a}\\b`
    );
    const neqEither = (a, b) => new RegExp(
        `\\b${a}\\b\\s*!==\\s*\\b${b}\\b|\\b${b}\\b\\s*!==\\s*\\b${a}\\b`
    );
    assert.match(src, eqEither('_chordRenderCacheSrc', 'src'), 'cache must key on src');
    assert.match(src, eqEither('_chordRenderCacheInverted', '_inverted'), 'cache must key on _inverted');
    assert.match(src, neqEither('_chordRenderCacheTemplates', 'chordTemplates'),
        'cache must key on chordTemplates (detected via !== for change-flag)');
});

test('chordTemplates change resets fretline preview and frame-mismatch warner', () => {
    const src = fs.readFileSync(highwayJs, 'utf8');
    // The cache-invalidation block must clear both _chordFretLineNotes
    // (so _updateFretLinePreview re-publishes with corrected isOpen
    // classification) and _frameMismatchWarned (so a chord ID warned
    // against stale templates re-validates against the corrected ones).
    // Non-greedy `[\s\S]*?` instead of `[^}]*` so a future nested
    // block inside the `if (templatesChanged) { … }` branch (e.g. an
    // inner conditional reset) doesn't break the match by introducing
    // a `}` before the symbol we're checking for.
    assert.match(src, /if\s*\(\s*templatesChanged\s*\)\s*\{[\s\S]*?_chordFretLineNotes\s*=\s*\[\][\s\S]*?\}/,
        'templatesChanged branch must reset _chordFretLineNotes');
    assert.match(src, /if\s*\(\s*templatesChanged\s*\)\s*\{[\s\S]*?_lastChordOnFretLine\s*=\s*null[\s\S]*?\}/,
        'templatesChanged branch must null _lastChordOnFretLine');
    assert.match(src, /if\s*\(\s*templatesChanged\s*\)\s*\{[\s\S]*?_frameMismatchWarned\.clear\(\)[\s\S]*?\}/,
        'templatesChanged branch must clear _frameMismatchWarned');
});