BigInt support

🐛 Bug Report

BigInt was introduced in Node.js v10.4.0. This feature is expected to be supported by jest. An script to test is added in this issue.

Currently the situation is:

• BigInt(x) can be used inside Jest but is only supported by the toBeEqual function, but not by toBeGreaterThan, toBeGreaterThanOrEqual, toBeLessThan or toBeLessThanOrEqual.

• The format 123n is not supported and causes an error without executing the tests:

To Reproduce

Use this script. As the format 123n is not supported and break the execution, you can comment the second test to check the other behaviours.

describe('BigInt', () => {
  test('It should accept BigInt("x") way', () => {
    const a = BigInt('123456789012345678901234567890');
    expect(typeof a).toEqual('bigint');
  });
  test('It should accept bigint in 123n format', () => {
    const a = 123456789012345678901234567890n;
    expect(typeof a).toEqual('bigint');
  });
  test('It should allow to do equal comparision', () => {
    const a = BigInt(2);
    expect(a).toEqual(BigInt(2));
  });
  test('It should allow to do greater than comparision', () => {
    const a = BigInt(2);
    expect(a).toBeGreaterThan(1);
  });
  test('It should allow to do greater than or equal comparision', () => {
    const a = BigInt(2);
    expect(a).toBeGreaterThanOrEqual(2);
  });
  test('It should allow to do less than comparision', () => {
    const a = BigInt(2);
    expect(a).toBeLessThan(3);
  });
  test('It should allow to do less than or equal comparision', () => {
    const a = BigInt(2);
    expect(a).toBeLessThanOrEqual(2);
  });
});

Expected behavior

• Jest should accept bigints in the format 123n.
• Functions of jest should support bigints.

Link to repl or repo (highly encouraged)

Script is already added to the issue

Run npx envinfo --preset jest

Paste the results here:

> npx envinfo --preset jest
npx: installed 1 in 2.649s

  System:
    OS: Windows 10
    CPU: x64 Intel(R) Core(TM) i7-7820HQ CPU @ 2.90GHz
  Binaries:
    Yarn: 1.7.0 - C:\Program Files\node\yarn.CMD
    npm: 6.1.0 - C:\Program Files\node\npm.CMD

[nickmccurdy]

Thanks, I didn’t realize Babel was loaded by default. I think it would be less surprising if it didn’t so Jest behaves like the current Node version as closely as possible. Or perhaps there could be different defaults in the node (off) and jsdom (on) environments.

[rickhanlonii]

+1 on a better error message if you want to submit the PR @MattMorgis