Jest custom matcher that ignores whitespace and new lines

toMatchIgnoreWhitespace.js

// To use:
// Put `<rootDir>/path/to/toMatchIgnoreWhitespace.js` in your Jest config under setupFiles
// Call it in your tests like this:
//    expect(received).toMatchIgnoreWhitespace(expected);

// Modified version of: https://gist.github.com/cassidoo/c726872858ce14e793a26619bd6a358f#file-customwhitespacematcher-js-L2

const { diffStringsUnified } = require('jest-diff');

const {
  matcherHint,
  printExpected,
  printReceived
} = require('jest-matcher-utils');

const replaceWhitespace = str =>
  str
    .replace(/(\r\n|\n|\r)/gm, '')
    .replace(/\s+/g, '')
    .trim();
const compressWhitespace = arr => arr.map(replaceWhitespace);

const name = `toMatchIgnoreWhitespace`;

expect.extend({
  toMatchIgnoreWhitespace(received, expected) {
    const [
      receivedWithCompresssedWhitespace,
      expectedWithCompresssedWhitespace
    ] = compressWhitespace([received, expected]);
    const pass =
      receivedWithCompresssedWhitespace === expectedWithCompresssedWhitespace;

    const message = pass
      ? () =>
          `${matcherHint(`.not.${name}`)}\n\n` +
          `Uncompressed expected value:\n` +
          `  ${printExpected(expected)}\n` +
          `Expected value with compressed whitespace to not equal:\n` +
          `  ${printExpected(expectedWithCompresssedWhitespace)}\n` +
          `Uncompressed received value:\n` +
          `  ${printReceived(received)}\n` +
          `Received value with compressed whitespace:\n` +
          `  ${printReceived(receivedWithCompresssedWhitespace)}`
      : () => {
          const diffString = diffStringsUnified(
            expectedWithCompresssedWhitespace,
            receivedWithCompresssedWhitespace
          );
          return (
            `${matcherHint(`.${name}`)}\n\n` +
            `Uncompressed expected value:\n` +
            `  ${printExpected(expected)}\n` +
            `Expected value with compressed whitespace to equal:\n` +
            `  ${printExpected(expectedWithCompresssedWhitespace)}\n` +
            `Uncompressed received value:\n` +
            `  ${printReceived(received)}\n` +
            `Received value with compressed whitespace:\n` +
            `  ${printReceived(receivedWithCompresssedWhitespace)}${
              diffString ? `\n\nDifference:\n\n${diffString}` : ``
            }`
          );
        };
    return {
      actual: received,
      expected,
      message,
      name,
      pass
    };
  }
});