ts-codemods

Codemods for Typescript built with jscodeshift.

Be careful when using codemods and always check the transformed code. Also remember that not every code migration can be easily 100% automated.

Development

To learn more about building codemods, check out these articles on my blog.

Install dependencies:

$ npm i

Run tests:

$ npm test

How to run codemods

Install jscodeshift:

$ npm i -g jscodeshift

Run a codemod for Typescript files:

$ jscodeshift --parser=ts -t <path-to-codemod> <file-path-or-pattern>

Included codemods

async-it

Transforms callback-based Mocha tests to async/await-based tests. It has options to remove or replace the done function used to return control after async operations.

Example:

command

jscodeshift -t ./src/async-it.ts <file> --parser=ts --rmDoneFunc=true

input code

import { describe } from 'mocha';
import { expect } from 'chai';

describe('a test suite', function () {
  it('a test', function (done) {
    setTimeout(() => {
      expect(true).to.be.true;
      done();
    }, 1);
  });
});

output code

import { describe } from 'mocha';
import { expect } from 'chai';

describe('a test suite', function () {
  it('a test', async function() {
    setTimeout(() => {
      expect(true).to.be.true;
    }, 1);
  });
});

Options:

• describeFuncName (string) The name of the Mocha describe function. Set by default to 'describe', can be changed to adapt the code to a different testing framework.
• itFuncName (string) The name of the Mocha it function. Set by default to 'it', can be changed to adapt the code to a different testing framework.
• itFuncName (string) The name of the Mocha skip function. Set by default to 'skip', can be changed to adapt the code to a different testing framework.
• doneFuncName (string) The name of the Mocha done function. Set by default to 'done', can be changed to adapt the code to a different testing framework.
• rmDoneFunc (boolean) Whether to remove the done function. Set by default to false.
• rmDoneFuncMode ('rm' OR 'throw') Done function removal mode: use 'rm' to remove function calls or 'throw' to replace them with an error throw. This allows you to choose how to carry out the manual review after running the codemod. A manual review is expected since the codemod cannot convert all the code automatically. Set by default to 'rm'.

async-supertest

Transforms callback-based Mocha tests to async/await-based tests. Also transforms supertest HTTP calls code from callback-based to async. This codemod uses the async-it codemod.

Example:

command

jscodeshift -t ./src/async-supertest.ts <file> --parser=ts

input code

import { describe } from 'mocha';
import { expect } from 'chai';
import { agent } from 'supertest';

describe('my api resource', function () {
  it('replies with code 200', function (done) {
    agent()
      .get('https://myapi.com/resource')
      .end(function (err, res) {
        if (err) return done(err);
        expect(res.statusCode).to.equal(200);
        expect(res.body.email).to.equal('[email protected]');
        done();
      });
  });
});

output code

import { describe } from 'mocha';
import { expect } from 'chai';
import { agent } from 'supertest';

describe('my api resource', function () {
  it('replies with code 200', async function() {
    const res = await agent()
      .get('https://myapi.com/resource');;
    expect(res.statusCode).to.equal(200);
    expect(res.body.email).to.equal('[email protected]');
  });
});