Adding jest-expect-message to a project tanks expect performance

[droberts-sea]

Bug

• package version: 1.0.2
• node version: v12.1.0
• npm (or yarn) version: npm 6.14.3
• jest version: 25.1.0
• Environment: 2015 MacBook Pro running OSX 10.15.4

Relevant code or config

// src/jest_expect_profile.test.js
const { performance } = require('perf_hooks');

const RUN_SIZE = 2000;

it('expect takes longer than expected', () => {
  const t0 = performance.now();
  for (let i = 0; i < RUN_SIZE; i += 1) {
    expect(i).toBe(i);
  }
  console.log(`Total time: ${performance.now() - t0} ms`);
});

it('wraping in a conditional is much quicker', () => {
  const t0 = performance.now();
  for (let i = 0; i < RUN_SIZE; i += 1) {
    if (i === RUN_SIZE) {
      expect(i).toBe(i);
    }
  }
  console.log(`Total time: ${performance.now() - t0} ms`);
});

/* package.json */
{
  "name": "jest-performance",
  "version": "1.0.0",
  "description": "",
  "main": "jest_expect_profile.test.js",
  "scripts": {
    "test": "jest"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "jest": "^25.4.0",
    "jest-expect-message": "^1.0.2"
  },
  "jest": {
    "setupFilesAfterEnv": [
      "jest-expect-message"
    ],
    "testEnvironment": "node"
  }
}

What you did:

Run expect in a loop, wrapped in some performance profiling, with and without the jest-expect-message library enabled.

What happened (please provide anything you think will help):

Test takes much, much longer (40-50x) with the library enabled!

Without jest-expect-message enabled

 PASS  src/jest_expect_profile.test.js
  ✓ expect takes longer than expected (150ms)
  ✓ wraping in a conditional is much quicker (2ms)

  console.log
    Total time: 132.83245699852705 ms

      at Object.<anonymous> (src/jest_expect_profile.test.js:10:11)

  console.log
    Total time: 0.04529799520969391 ms

      at Object.<anonymous> (src/jest_expect_profile.test.js:20:11)

Test Suites: 1 passed, 1 total
Tests:       2 passed, 2 total
Snapshots:   0 total
Time:        1.064s, estimated 7s
Ran all test suites related to changed files.

With jest-expect-message enabled

 PASS  src/jest_expect_profile.test.js (6.022s)
  ✓ expect takes longer than expected (5535ms)
  ✓ wraping in a conditional is much quicker (1ms)

  console.log
    Total time: 5523.3286210000515 ms

      at Object.<anonymous> (src/jest_expect_profile.test.js:10:11)

  console.log
    Total time: 0.04469999670982361 ms

      at Object.<anonymous> (src/jest_expect_profile.test.js:20:11)

Test Suites: 1 passed, 1 total
Tests:       2 passed, 2 total
Snapshots:   0 total
Time:        6.08s
Ran all test suites related to changed files.

Reproduction repository (if possible):

https://github.com/droberts-ada/jest-performance