assertSnapshot.js

const fs = require('node:fs/promises');
const assert = require('node:assert/strict');

const windowNewlineRegexp = /\r/g;

function replaceWindowsLineEndings(str) {
  return str.replace(windowNewlineRegexp, '');
}

function getSnapshotPath(filename) {
  return filename + '.snap';
}

async function assertSnapshot(actual, filename = process.argv[1]) {
  const snapshot = getSnapshotPath(filename);
  if (process.env.NODE_REGENERATE_SNAPSHOTS) {
    await fs.writeFile(snapshot, actual);
    console.log(`Snapshot regenerated: ${snapshot}`);
  } else {
    let expected;
    try {
      expected = await fs.readFile(snapshot, 'utf8');
    } catch (e) {
      if (e.code === 'ENOENT') {
        await fs.writeFile(snapshot, actual);
        console.log(`Snapshot created: ${snapshot}`);
        return;
      }
      throw e;
    }
    assert.strictEqual(actual, replaceWindowsLineEndings(expected));
  }
}

module.exports = {
  assertSnapshot
};

assertSnapshotUsingJestSnapshot.js

const assert = require('assert');
const { SnapshotState, toMatchSnapshot } = require('jest-snapshot');

function getSnapshotPath(filename) {
  return filename + '.snap';
}

/**
 * @param {any} actual
 * @param {{name: string; testPath?: string}} testContext
 */
async function assertSnapshot(actual, { name: currentTestName, testPath = process.argv[1] }) {
  const snapshotPath = getSnapshotPath(testPath);
  const NODE_UPDATE_SNAPSHOT = process.env.NODE_UPDATE_SNAPSHOT || 'new';
  const snapshotState = new SnapshotState(snapshotPath, {
    updateSnapshot: /^(all|new|none)$/.test(NODE_UPDATE_SNAPSHOT) ? NODE_UPDATE_SNAPSHOT : 'all'
  });
  const result = ({
    snapshotState,
    currentTestName,
    toMatchSnapshot
  }).toMatchSnapshot(actual);

  snapshotState.save();

  assert(result.pass, result.pass ? '' : result.message());
}

module.exports = {
  assertSnapshot: assertSnapshot
};