node_modules/browserify/test/bundle-bundle-external.js

var browserify = require('../');
var test = require('tap').test;

var pubdir = __dirname;
var dir = pubdir + '/bundle-bundle-external';

var opt = {
    debug: true,
    basedir: pubdir,
    exposeAll: true
};

test('bundle bundle external', function (t) {
    t.plan(1);
    var bundle1 = browserify(opt);
    var name = dir + '/foo.js';
    bundle1.require(name, { entry: true, expose: name, basedir: pubdir });

    var bundle2 = browserify({
        debug: true,
        basedir: pubdir,
        entries: [ dir + '/baz.js' ]
    });

    // adding and removing this line causes failure //
    //bundle2.external(bundle1);

    bundle2.bundle(function(err, src) {
        t.ifError(err);
    });
});