test/parallel/test-repl-built-in-modules.js

'use strict';

require('../common');
const assert = require('assert');
const cp = require('child_process');

function runREPLWithAdditionalFlags(flags) {
  // Use -i to force node into interactive mode, despite stdout not being a TTY
  const args = ['-i'].concat(flags);
  const ret = cp.execFileSync(process.execPath, args, {
    input: 'require(\'events\');\nrequire(\'wasi\');',
    encoding: 'utf8',
  });
  return ret;
}

// Run REPL in normal mode.
let stdout = runREPLWithAdditionalFlags([]);
assert.match(stdout, /\[Function: EventEmitter\] {/);
assert.match(
  stdout,
  /Uncaught Error: Cannot find module 'wasi'[\w\W]+- <repl>\n/);

// Run REPL with '--experimental-wasi-unstable-preview1'
stdout = runREPLWithAdditionalFlags([
  '--experimental-wasi-unstable-preview1',
]);
assert.match(stdout, /\[Function: EventEmitter\] {/);
assert.doesNotMatch(
  stdout,
  /Uncaught Error: Cannot find module 'wasi'[\w\W]+- <repl>\n/);
assert.match(stdout, /{ WASI: \[class WASI\] }/);