gitmost/packages/git-sync/test/roundtrip-corpus.test.ts

import { readFile } from 'node:fs/promises';
import { readdirSync } from 'node:fs';
import { fileURLToPath } from 'node:url';
import { dirname, join } from 'node:path';
import { describe, expect, it } from 'vitest';
import {
  convertProseMirrorToMarkdown,
  markdownToProseMirror,
  docsCanonicallyEqual,
} from 'docmost-client';

// Resolve fixtures relative to this test file so the test is CWD-independent.
const here = dirname(fileURLToPath(import.meta.url));
const CORPUS_DIR = join(here, 'fixtures', 'corpus');
const KNOWN_LIMITATIONS_DIR = join(here, 'fixtures', 'known-limitations');

/** Run a single document through export -> import -> export. */
async function roundTrip(doc: any) {
  const md1 = convertProseMirrorToMarkdown(doc);
  const doc2 = await markdownToProseMirror(md1);
  const md2 = convertProseMirrorToMarkdown(doc2);
  return { md1, md2, doc2 };
}

describe('round-trip corpus (SPEC §11)', () => {
  // Discover the corpus synchronously at collection time so each fixture gets
  // its own `it` with the file name in the test title.
  const files = readdirSync(CORPUS_DIR)
    .filter((name) => name.endsWith('.json'))
    .sort();

  it('has a non-empty corpus', () => {
    expect(files.length).toBeGreaterThan(0);
  });

  for (const name of files) {
    it(`${name}: markdown byte-stable AND canonically stable`, async () => {
      const doc = JSON.parse(await readFile(join(CORPUS_DIR, name), 'utf8'));
      const { md1, md2, doc2 } = await roundTrip(doc);

      // 1) The byte-stable markdown property git actually needs.
      expect(md2, `${name}: markdown not byte-stable`).toBe(md1);
      // 2) Semantic stability (block ids stripped, default-null normalized).
      expect(
        docsCanonicallyEqual(doc, doc2),
        `${name}: document not canonically stable`,
      ).toBe(true);
    });
  }
});

// ---------------------------------------------------------------------------
// KNOWN CONVERTER LIMITATIONS (isolated so they do NOT make CI red).
//
// SPEC §11 explicitly flags images and diagrams as high round-trip risk. These
// fixtures are kept OUT of the green corpus above and asserted with `it.fails`
// so the documented divergence is locked in (the test FAILS if the converter
// ever starts round-tripping them — at which point promote the fixture into
// the corpus). The precise divergences for `image-diagrams.json` are:
//
//   * A BLOCK-LEVEL image preceded by a paragraph is NOT byte-stable on the
//     FIRST re-export. The HTML re-parser hoists the block <img> out of its
//     line and leaves an empty paragraph behind, so `paragraph` + `![..](..)`
//     re-imports as paragraph + empty-paragraph + image; the empty paragraph
//     adds one blank line, so export #2 grows by a one-time "\n\n" (md1 !== md2).
//     This is NOT non-convergence: the growth happens exactly ONCE. The doc
//     CONVERGES to a fixpoint after one extra `export→import→export` pass — the
//     empty paragraph is already present after the first import, so export #2
//     and export #3 are byte-identical (md2 === md3, verified).
//
//   * drawio / excalidraw diagrams gain `data-align="center"` on the second
//     export: the schema's diagram `align` attribute has a NON-null default of
//     "center", which materializes on import; the converter only emits
//     data-align when set, so it appears on export #2 but not #1. Like the
//     image case, this is one-time and converges after one extra pass.
//
//   * A STANDALONE block image (no preceding paragraph) IS byte-stable from
//     export #1 (md1 === md2) — but it is still NOT canonically stable: on
//     import the bare <img> is wrapped, gaining a leading EMPTY paragraph, so
//     the canonical doc differs by that spurious paragraph node even though the
//     markdown bytes match.
//
// Resolution (SPEC §11, "normalize-on-write"): rather than deep-fixing the
// converter, the engine runs ONE `export→import→export` pass when writing into
// the vault; from that fixpoint onward the form is byte-stable, so git sees no
// phantom diff. The green corpus above avoids these one-time asymmetries by
// pre-authoring the materialized defaults (e.g. `align: "center"` on the
// diagrams in 06-diagrams.json) so a single pass is already at the fixpoint.
// ---------------------------------------------------------------------------
describe('round-trip KNOWN LIMITATIONS (SPEC §11 image/diagram risk)', () => {
  it.fails(
    'image-diagrams.json is NOT byte-stable on export #1 (block image hoist + diagram align default; converges after one extra pass — SPEC §11 normalize-on-write)',
    async () => {
      const doc = JSON.parse(
        await readFile(join(KNOWN_LIMITATIONS_DIR, 'image-diagrams.json'), 'utf8'),
      );
      const { md1, md2 } = await roundTrip(doc);
      // This assertion FAILS today (documented divergence). `it.fails` turns a
      // failing body into a PASS; if the converter is fixed this flips and the
      // test goes red, prompting promotion into the green corpus.
      expect(md2).toBe(md1);
    },
  );
});