notes/node_modules/yargs/test/_.js

var spawn = require('child_process').spawn,
    should = require('chai').should();

describe('bin script', function () {

    it('should run as a shell script with no arguments', function (done) {
        testCmd('./bin.js', [], done);
    });

    it('should run as a shell script with arguments', function (done) {
        testCmd('./bin.js', [ 'a', 'b', 'c' ], done);
    });

    it('should run as a node script with no arguments', function (done) {
        testCmd('node bin.js', [], done);
    });

    it('should run as a node script with arguments', function (done) {
        testCmd('node bin.js', [ 'x', 'y', 'z' ], done);
    });

    describe('path returned by "which"', function () {

        beforeEach(function () {
            this.which = spawn('which', ['node']);
        });

        it('should match the actual path to the script file', function (done) {
            this.which.stdout.on('data', function (buf) {
                testCmd(buf.toString().trim() + ' bin.js', [], done);
            });
            this.which.stderr.on('data', done);
        });

        it('should match the actual path to the script file, with arguments', function (done) {
            this.which.stdout.on('data', function (buf) {
                testCmd(buf.toString().trim() + ' bin.js', [ 'q', 'r' ], done);
            });
            this.which.stderr.on('data', done);
        });

    });

});

function testCmd(cmd, args, done) {

    var oldDir = process.cwd();
    process.chdir(__dirname + '/_');
    
    var cmds = cmd.split(' ');
    
    var bin = spawn(cmds[0], cmds.slice(1).concat(args.map(String)));
    process.chdir(oldDir);
    
    bin.stderr.on('data', done);
    
    bin.stdout.on('data', function (buf) {
        var _ = JSON.parse(buf.toString());
        _.map(String).should.deep.equal(args.map(String));
        done();
    });

}