koala73/worldmonitor · error · Error

The selected shard contains no test files

Error message

The selected shard contains no test files

What it means

After partitioning the resolved files across `total` shards, the runner selects shard `index`. If that particular shard ends up with zero files (possible even when index <= total and total <= files.length, e.g. with skewed timing-based partitioning), it throws 'The selected shard contains no test files' so CI fails loudly instead of passing vacuously.

Solutions

1. Rerun with `--list` to inspect which files each shard receives, then choose a shard index that has files
2. Regenerate/refresh the timing data file so partitioning is balanced, or delete stale timing data if regeneration is automatic
3. Reduce the shard TOTAL or pick a different INDEX (e.g. --shard 1/2 instead of --shard 3/3)

Example fix

// before
node scripts/run-data-tests.mjs --shard 4/4 'tests/data/**/*.test.mjs'
// after (verify with --list first)
node scripts/run-data-tests.mjs --list --shard 1/4 'tests/data/**/*.test.mjs'
node scripts/run-data-tests.mjs --shard 1/4 'tests/data/**/*.test.mjs'

const selected = partitionTests(files, durations, total)[index - 1];
if (!selected.length && total > 1) {
  // fall back to a shard known to have files, or fail with diagnostics
  console.error(JSON.stringify(partitionTests(files, durations, total).map(p => p.length)));
  throw new Error(`Shard ${index}/${total} empty; sizes above`);
}

const shardHasFiles = (files, durations, index, total) => partitionTests(files, durations, total)[index - 1].length > 0;

try {
  await run();
} catch (err) {
  if (err.message === 'The selected shard contains no test files') {
    console.error('Rebalance shards: refresh timing data or lower shard TOTAL; inspect with --list.');
    process.exit(2);
  }
  throw err;
}

When it happens

Trigger: Running with `--shard N/T` where the timing-based partition assigns no files to shard N — e.g. more shards than meaningfully distributable files, or a timing JSON (`timingPath`) that marks other files much slower so shard N gets nothing.

Common situations: Timing data file stale or skewed after test changes, pushing all files into other shards; shard index chosen manually in CI that no longer receives files after the suite changed; rerunning a shard in isolation after the file set shrank.

Understand the failure class

Background: EmptyResultError / "no results found": when an API or scraper succeeds but returns zero rows — this error's family across 9 libraries.

Related errors

• Shard count exceeds the test file count
• Supply test files or globs
• No test files match ${pattern}
• global fetch is unavailable — Node 18+ is required
• --args must be valid JSON: ${err.message}

AI-assisted analysis of koala73/worldmonitor@7d06c8633d (2026-09-15). Data as JSON: /api/errors/aa874801fc152fe6. Report an issue: GitHub.

Appendix: source

Thrown at scripts/run-data-tests.mjs:63

  if (values.shard) {
    const match = /^([1-9]\d*)\/([1-9]\d*)$/.exec(values.shard);
    if (!match) throw new Error('Shard must be INDEX/TOTAL (for example 1/2)');
    [index, total] = match.slice(1).map(Number);
    if (!Number.isSafeInteger(index) || !Number.isSafeInteger(total) || index > total) {
      throw new Error('Shard index must be between 1 and TOTAL');
    }
  }
  if (!positionals.length) throw new Error('Supply test files or globs');
  const files = [...new Set(positionals.flatMap((pattern) => {
    const matches = (existsSync(pattern) && statSync(pattern).isFile() ? [pattern] : globSync(pattern))
      .map((file) => file.split(sep).join('/'));
    if (!matches.length) throw new Error(`No test files match ${pattern}`);
    return matches;
  }))];
  const durations = JSON.parse(readFileSync(timingPath, 'utf8'));
  if (total > files.length) throw new Error('Shard count exceeds the test file count');
  const selected = partitionTests(files, durations, total)[index - 1];
  if (!selected.length) throw new Error('The selected shard contains no test files');
  if (values.list) {
    console.log(JSON.stringify(selected));
    return 0;
  }
  console.log(`Data tests: ${selected.length}/${files.length} files, shard ${index}/${total}, concurrency ${values.concurrency}`);
  const env = { ...process.env };
  // This is a new test run, even when a contract test invokes the CLI.
  delete env.NODE_TEST_CONTEXT;
  const timingFd = values.timings ? openSync(values.timings, 'w') : undefined;
  let success = false;
  try {
    const events = run({
      files: selected.map((file) => resolve(file)),
      concurrency: Number(values.concurrency),
      timeout: 120000,
      execArgv: ['--import', 'tsx'],
      testNamePatterns: values['test-name-pattern'],
      env,

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