mochajs/mocha · error · Error

Not enough non-option arguments: got 0, need at least 1

Error message

Not enough non-option arguments: got 0, need at least 1

What it means

The `mocha init` command requires exactly one positional argument: the destination path where the client-side Mocha setup (browser test scaffolding) will be created. The public `parse` function in lib/cli/init.js destructures the first argument and throws this error when no path argument was supplied, so it cannot know where to write the files.

Source

Thrown at lib/cli/init.js:18

/**
 * Command module for "init" command
 *
 * @private
 * @module
 */

import fs from "node:fs";
import path from "node:path";

export const command = "init <path>";

export const description = "create a client-side Mocha setup at <path>";

export const parse = (args) => {
  const [pathArg] = args;
  if (!pathArg) {
    throw new Error("Not enough non-option arguments: got 0, need at least 1");
  }
  return { _: [], path: path.normalize(pathArg) };
};

export const handler = (argv) => {
  const destdir = argv.path;
  const srcdir = path.join(import.meta.dirname, "..", "..");
  fs.mkdirSync(destdir, { recursive: true });
  const css = fs.readFileSync(path.join(srcdir, "mocha.css"));
  const js = fs.readFileSync(path.join(srcdir, "mocha.js"));
  const tmpl = fs.readFileSync(
    path.join(srcdir, "lib", "browser", "template.html"),
  );
  fs.writeFileSync(path.join(destdir, "mocha.css"), css);
  fs.writeFileSync(path.join(destdir, "mocha.js"), js);
  fs.writeFileSync(path.join(destdir, "tests.spec.js"), "");
  fs.writeFileSync(path.join(destdir, "index.html"), tmpl);
};

View on GitHub (pinned to 6bcbee4fd9)

Solutions

1. Pass the destination directory: `mocha init ./tests` (or `mocha init <path>`).
2. Check shell variable expansion/quoting — echo the command to confirm the path argument is actually present.
3. If invoking parse() programmatically, pass `parse(['./my/path'])` with at least one string element.

Example fix

// before
$ mocha init
// Error: Not enough non-option arguments: got 0, need at least 1

// after
$ mocha init ./test-browser

const args = process.argv.slice(2);
if (args.length < 1 || args[0].startsWith('-')) {
  console.error('Usage: mocha init <path>');
  process.exit(1);
}

const hasPathArg = (args) => Array.isArray(args) && typeof args[0] === 'string' && args[0].length > 0;

try {
  init.parse(process.argv.slice(3));
} catch (err) {
  if (err.message.startsWith('Not enough non-option arguments')) {
    console.error('Usage: mocha init <path>');
    process.exit(1);
  }
  throw err;
}

When it happens

Trigger: Running `mocha init` (or `mocha init --reporter spec` etc.) with zero non-option arguments; also `parse([])` or `parse(['--some-option'])` called programmatically with no positional.

Common situations: Developers forgetting the output directory when bootstrapping browser tests; shell quoting issues that swallow the argument (e.g. empty variable expansion like `mocha init $UNSET_PATH`); migrating CI scripts where the path argument was dropped.

Related errors

• Not enough arguments following: ${name}
• ERR_MOCHA_UNSUPPORTED
• ERR_MOCHA_MISSING_ARGUMENT
• Missing runner argument
• Missing runner argument

AI-assisted analysis of mochajs/mocha@6bcbee4fd9 (2026-09-01). Data as JSON: /api/errors/760177c6e7eeac49. Report an issue: GitHub.