Clean release snapshot

tests/js/beats_loaded.test.js

@@ -0,0 +1,79 @@
+// Verify static/highway.js emits `beats:loaded` exactly once when the
+// WebSocket delivers the song's beats array, with `{ count }` payload.
+// Plugins that need to know when beats are available (metronome, beat-
+// snapping editors, sync visualizers) consume this contract.
+//
+// Same isolation strategy as the other tests/js/ files — extract just
+// the relevant case-block source by string matching and exercise it in
+// a vm sandbox with stubbed deps.
+
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+
+const HIGHWAY_JS = path.join(__dirname, '..', '..', 'static', 'highway.js');
+
+// Extract a single switch case body so assertions can match against just
+// that block rather than a fixed-length slice (more robust to harmless
+// edits adjacent to the case).
+function getCaseBlock(src, label) {
+    const start = src.indexOf(`case '${label}'`);
+    assert.ok(start !== -1, `case '${label}' not found in highway.js`);
+    const tail = src.slice(start);
+    const nextCase = tail.search(/\n\s*case\s+['"]/);
+    const nextDefault = tail.search(/\n\s*default\s*:/);
+    let end = tail.length;
+    if (nextCase > 0) end = Math.min(end, nextCase);
+    if (nextDefault > 0) end = Math.min(end, nextDefault);
+    return tail.slice(0, end);
+}
+
+test('beats:loaded emit is wired into the WS beats case', () => {
+    // Source-level guard: catch a future contributor removing the emit
+    // (regression) or replacing window.slopsmith.emit with something
+    // else (intentional refactor — this test then needs updating).
+    const src = fs.readFileSync(HIGHWAY_JS, 'utf8');
+    const block = getCaseBlock(src, 'beats');
+    assert.match(
+        block,
+        /window\.slopsmith\.emit\(\s*['"]beats:loaded['"]/,
+        'beats case must emit beats:loaded',
+    );
+    assert.match(
+        block,
+        /count:\s*beats\.length/,
+        'beats:loaded payload must include count = beats.length',
+    );
+});
+
+test('beats:loaded emit is guarded against missing window.slopsmith', () => {
+    // The WS handler can fire before the slopsmith namespace is defined
+    // (early in app boot). The emit must be guarded so a missing
+    // namespace doesn't throw inside the WS message dispatcher.
+    // Looser pattern accepts any guard that reads window.slopsmith
+    // (including typeof checks and combined conditions) rather than
+    // mandating the exact `if (window.slopsmith)` form.
+    const src = fs.readFileSync(HIGHWAY_JS, 'utf8');
+    const block = getCaseBlock(src, 'beats');
+    assert.match(
+        block,
+        /if\s*\(\s*[^)]*window\.slopsmith\b[^)]*\)/,
+        'beats:loaded emit must be guarded against a missing window.slopsmith',
+    );
+});
+
+test('beats:loaded guard verifies emit is callable (typeof check)', () => {
+    // A partially-attached namespace (window.slopsmith exists but emit
+    // isn't a function yet during early boot) would throw without this
+    // extra check. A truthy check (`window.slopsmith.emit && ...`) lets
+    // non-callable values pass; require an explicit typeof === 'function'
+    // check so the guard catches that real edge.
+    const src = fs.readFileSync(HIGHWAY_JS, 'utf8');
+    const block = getCaseBlock(src, 'beats');
+    assert.match(
+        block,
+        /typeof\s+window\.slopsmith\.emit\s*===\s*['"]function['"]/,
+        'guard must use typeof === \'function\' (not just truthy) to confirm emit is callable',
+    );
+});