jest-expect-codemod

CodeMods for migrating chai.assert, chai.expect, assert -based test assertions to jest's expect assertions

This repository contains a collection of codemod scripts for use with JSCodeshift.

Currently, we don't support migration of all the assertions provided by these libraries, but PRs to add them are welcome. :-)

Setup & Run

git clone https://github.com/devenbansod/jest-expect-codemod.git
yarn run shift -t transformations/<codemod-script> <file/folder to be converted>

Use the -d option for a dry-run and use -p to print the output for comparison.

Included Scripts

Migrate from assert

yarn run shift -t jest-expect-codemod/transforms/assert.js <file>

Migrate from chai.assert

yarn run shift -t jest-expect-codemod/transforms/chaiAssert.js <file>

Migrate from chai.expect

yarn run shift -t jest-expect-codemod/transforms/chaiExpect.js <file>

Samples

Migrate from assert

Input

module.exports = function() {
  const a = 1;
  assert.equal(a, 1);

  const b = {
    a: 2,
  };
  assert.deepEqual(b, {
    a: 2,
  });

  const c = true;
  assert.ok(c);

  const d = 5;
  assert.notEqual(d, 3);

  assert.throws(() => {
    throw new Error("Wrong value");
  }, /value/);

  const e = 1;
  assert.strictEqual(e, 1);
};

Output

module.exports = function() {
  const a = 1;
  expect(a).toBe(1);

  const b = {
    a: 2,
  };
  expect(b).toEqual({
    a: 2,
  });

  const c = true;
  expect(c).toBeTruthy();

  const d = 5;
  expect(d).not.toBe(3);

  expect(() => {
    throw new Error("Wrong value");
  }).toThrow(/value/);

  const e = 1;
  expect(e).toBe(1);
};

Migrate from chai.assert

Input

module.exports = function() {
  const a = 1;
  assert.equal(a, 1);
  assert.notEqual(a, 3);

  const b = {
    a: 2,
  };
  assert.deepEqual(b, {
    a: 2,
  });
  assert.notDeepEqual(b, {
    c: 2,
  });

  const c = true;
  assert.isNotOk(!c);
  assert.isOk(c);

  assert.isNotTrue(!c);
  assert.isTrue(c);

  assert.isNotFalse(!c);
  assert.isNotFalse(c);

  const d = 1;
  assert.strictEqual(d, 1);
  assert.notStrictEqual(d, 2);
};

Migrate from chai.expect

Input

module.exports = function() {
  const a = 1;
  expect(a).to.equal(1);

  const b = {
    a: 2,
  };
  expect(b).to.eql({
    a: 2,
  });
};

Output

module.exports = function() {
  const a = 1;
  expect(a).toBe(1);

  const b = {
    a: 2,
  };
  expect(b).toEqual({
    a: 2,
  });
};

Motivation

This was initially written with a motivation to ease the migration the tests in babel to Jest Expect assertions (tracked at #7476).