codemod: remove wrapHandler

transform.js

/**
 * turns e.g.
 *
 * ```
 * const wrapHandler = require(`../lib/wrap-handler`);
 * const {list, spawn} = require(`../util/package`);
 *
 * module.exports = {
 *   command: `exec cmd [args...]`,
 *   desc: `Run a command in each package directory`,
 *   builder: {},
 *   handler: wrapHandler(async ({cmd, args}) => {
 *     for (const packageName of await list()) {
 *       await spawn(packageName, cmd, args);
 *     }
 *   })
 * };
 * ```
 * into
 *
 * ```
 * const {list, spawn} = require(`../util/package`);
 *
 * module.exports = {
 *   command: `exec cmd [args...]`,
 *   desc: `Run a command in each package directory`,
 *   builder: {},
 *   async handler({cmd, args}) {
 *     for (const packageName of await list()) {
 *       await spawn(packageName, cmd, args);
 *     }
 *   }
 * };
 * ```
 */


module.exports = function transform({source}, {jscodeshift}) {
  const j = jscodeshift;
  const root = jscodeshift(source);

  // remove calls to wrapHandler and change the handler property to a method
  // shorthand
  root
    .find(jscodeshift.CallExpression, {
      callee: {
        name: `wrapHandler`
      }
    })
    .replaceWith((p) => {
      // seems there's a bug in jscodeshift where it doesn't accept the async
      // param in the functionExpression factory, so we need to do this bit of
      // silliness instead
      const res = jscodeshift.functionExpression(jscodeshift.identifier(`handler`), p.node.arguments[0].params, p.node.arguments[0].body);
      res.async = true;
      return res;
    })
    .forEach((p) => {
      p.parentPath.node.method = true;
    });

  // Remove require of wrapHandler
  root
    .find(j.VariableDeclarator, {
      id: {type: `Identifier`, name: `wrapHandler`},
      init: {callee: {name: `require`}}
    })
    .forEach((p) => j(p).remove());

  // Remove leading blank lines but ensure we have a newline at the end of the
  // file
  return `${root.toSource().trim()}\n`;
};

Instead of wrapping every handler, use something like the following in your yargs entrypoint.

process.on(`unhandledRejection`, (err) => {
  const cmd = `bowman ${process.argv.slice(2).join(` `)}`;
  console.error(`Failed to execute "${cmd}"`);
  console.error(err.toString());
  if (argv.debug) {
    console.error(err);
  }
  // eslint-disable-next-line no-process-exit
  process.exit(E_UNHANDLED_REJECTION);
});

Note: this doesn't handle import syntax for loading wrapHandler, but it's a small modification to add it.