Merge pull request #3386 from open-gsd/test/3339-fold-state-model-profile

tests/frontmatter.test.cjs

@@ -2284,3 +2284,89 @@ describe('#2847: schema name consistency between gsd-planner.md and src/frontmat
 });
   });
 }
+
+// ────────────────────────────────────────────────────────────────────────
+// Folded from tests/issue-2977-frontmatter-bom.test.cjs — test-hygiene sweep #3339 (H3 Wave 7)
+// ────────────────────────────────────────────────────────────────────────
+{
+  const { describe: __foldDescribe } = require('node:test');
+  __foldDescribe('folded:issue-2977-frontmatter-bom', () => {
+'use strict';
+
+/**
+ * Regression test for #2977 — `extractFrontmatter` returns {} for any file whose
+ * frontmatter fence is preceded by a UTF-8 BOM (Windows PowerShell `>`/`Out-File`,
+ * several editors). The `startsWith('---')` byte-0 check fails on any leading byte,
+ * so every frontmatter field silently disappears with no error.
+ *
+ * The fix strips a leading UTF-8 BOM (U+FEFF) before the fence check. Scope: BOM only
+ * (acceptance criteria 1-3). The generalized "arbitrary content before the fence" fork
+ * (tolerate vs diagnose) is a product-intent decision, surfaced in the PR — out of scope.
+ *
+ * Matrix: .gsd/bug/fix/2977-frontmatter-bom-tolerance/50-test-matrix.md
+ */
+
+const { describe, test } = require('node:test');
+const assert = require('node:assert/strict');
+const { extractFrontmatter } = require('../gsd-core/bin/lib/frontmatter.cjs');
+
+const BOM = '\uFEFF';
+
+describe('extractFrontmatter BOM tolerance (#2977)', () => {
+  test('bomPrefixedFrontmatterParses', () => {
+    // Row 1 (failing-first regression): a BOM-prefixed frontmatter document parses
+    // identically to the same document without the BOM.
+    const clean = '---\ntitle: T\nphase: "01"\nstatus: passed\n---\n\n# Body\n';
+    const bommed = BOM + clean;
+    const expected = extractFrontmatter(clean, 'a.md');
+    const actual = extractFrontmatter(bommed, 'a.md');
+    assert.deepEqual(actual, expected, 'BOM-prefixed frontmatter must parse identically to no-BOM');
+    assert.strictEqual(actual.title, 'T', 'title field recovered');
+    assert.strictEqual(actual.phase, '01', 'phase field recovered');
+    assert.strictEqual(actual.status, 'passed', 'status field recovered');
+  });
+
+  test('bomWithCrlfParses', () => {
+    // Row 2 (acceptance #2): BOM + CRLF line endings together still parse correctly.
+    const clean = '---\r\ntitle: T\r\nphase: "01"\r\n---\r\n\r\n# Body\r\n';
+    const bommed = BOM + clean;
+    const actual = extractFrontmatter(bommed, 'a.md');
+    assert.strictEqual(actual.title, 'T', 'title recovered (BOM + CRLF)');
+    assert.strictEqual(actual.phase, '01', 'phase recovered (BOM + CRLF)');
+  });
+
+  test('bomWithNoFrontmatterStaysEmpty', () => {
+    // Row 3 (acceptance #3): a BOM prefixing a document with no frontmatter (or genuinely
+    // empty frontmatter) returns {} with no false diagnostic — same as no-BOM.
+    assert.deepEqual(extractFrontmatter(BOM + 'just plain text', 'a.md'), {}, 'BOM + no frontmatter -> {}');
+    assert.deepEqual(extractFrontmatter(BOM + '', 'a.md'), {}, 'BOM + empty -> {}');
+    // A thematic-break-first-line Markdown doc (--- then prose) must stay {} — protected by
+    // the existing false-positive threshold; the BOM strip must not lower that bar.
+    assert.deepEqual(extractFrontmatter(BOM + '---\n\nA horizontal rule, not frontmatter.\n', 'a.md'), {},
+      'BOM + thematic-break Markdown -> {} (no false diagnostic)');
+  });
+
+  test('bomAcrossArtifactTypes', () => {
+    // Row 4 (acceptance #1 across artifact types): each frontmatter-bearing artifact shape
+    // recovers its fields when BOM-prefixed.
+    const cases = [
+      { name: 'STATE.md', body: '---\ncurrent_phase: "01"\nstatus: "In progress"\n---\n\n# State\n', expect: { current_phase: '01', status: 'In progress' } },
+      { name: 'PLAN.md', body: '---\nphase: "01"\nplan: "01-01"\nstatus: "done"\n---\n\n# Plan\n', expect: { phase: '01', plan: '01-01', status: 'done' } },
+      { name: 'SUMMARY.md', body: '---\none-liner: "shipped the thing"\n---\n\n# Summary\n', expect: { 'one-liner': 'shipped the thing' } },
+      { name: 'UAT.md', body: '---\nphase: "02"\nverdict: "pass"\n---\n\n# UAT\n', expect: { phase: '02', verdict: 'pass' } },
+    ];
+    for (const c of cases) {
+      const actual = extractFrontmatter(BOM + c.body, c.name);
+      assert.deepEqual(actual, c.expect, `${c.name}: BOM-prefixed frontmatter must recover fields`);
+    }
+  });
+
+  test('controlNoBom', () => {
+    // Row 5 (no regression): no BOM, valid frontmatter still parses correctly (unchanged).
+    const actual = extractFrontmatter('---\ntitle: T\nphase: "01"\n---\n\n# Body\n', 'a.md');
+    assert.strictEqual(actual.title, 'T');
+    assert.strictEqual(actual.phase, '01');
+  });
+});
+  });
+}