babel-node

#!/usr/bin/env bash
set -euo pipefail

node -r ./babel-node.register "$@"

babel-node.register.js

const path = require('path');

require('@babel/register')({
  extensions: ['.js', '.jsx', '.ts', '.tsx'],

  // ... more config ...
});

jest-ts

#!/usr/bin/env bash
set -euo pipefail

./babel-node ./jest-ts-run.ts "$@"

jest-ts-run.ts

import { run } from 'jest';
import path from 'path';

const argsIn = process.argv.slice(2);
const argsOut: string[] = [];

let configFile;
let i = 0;
while (i < argsIn.length) {
  if (argsIn[i].startsWith('--config')) {
    if (argsIn[i].startsWith('--config=')) {
      configFile = argsIn[i].replace('--config=', '');
    } else if (i + 1 < argsIn.length) {
      configFile = argsIn[i + 1];
      i++;
    }
  } else {
    argsOut.push(argsIn[i]);
  }
  i++;
}
if (!configFile) {
  throw new Error('Missing --config');
}

let config;
if (configFile.endsWith('.ts')) {
  config = JSON.stringify(require(path.resolve(configFile)));
} else {
  config = configFile;
}
argsOut.unshift('--config', config);

run(argsOut);