Simple Tested Website in NodeJS

maintainable-code-js.js

'use strict';

var http = require('http');
var url = require('url');

function OK(contentType, body, otherHeaders = {}) {
  return [
    200,
    Object.assign({},
      otherHeaders,
      {'Content-Type': contentType}
    ),
    body
  ];
}

function Dispatcher(requestUnpacker) {
  if (! (this instanceof Dispatcher)) {
    return new Dispatcher(...arguments);
  } else {
    // Do instance-specific stuff here...
    this.requestUnpacker = requestUnpacker;
  }
}
Dispatcher.prototype = {
  dispatch(request) {
    let [pathname, target] = this.requestUnpacker.unpack(request);
    let result = 'No Result...';

    switch (pathname) {
      case '/hello':
      result = `Hello, ${target}!`;

      break;

      case '/length':
      result = `${target.length}`;

      break;
    }

    return OK('text/plain', result);
  }
}

function RequestUnpacker(defaultTarget='No One') {
  if (! (this instanceof RequestUnpacker) ) {
    return new RequestUnpacker(...arguments);
  } else {
    // Do instance-specific stuff here...
    this.defaultTarget = defaultTarget;
  }
}
RequestUnpacker.prototype = {
  unpack(request) {
    let {url:reqUrl} = request;
    let {pathname, query:{target=this.defaultTarget}} = url.parse(reqUrl,true);
    return [pathname,target];
  }
}

function wiring() {
  let requestUnpacker = RequestUnpacker();
  let dispatcher = Dispatcher(requestUnpacker);
  return (req,res) => {
    let [status, headers, content] = dispatcher.dispatch(req);
    res.writeHead(status, headers);
    res.end(content);
  }
}

(() => {
  // given
  let contentType = 'text/plain';
  let body = 'the body';
  let someHeaderValue = 'the value';

  // when
  let [actualStatus, {"Content-Type":actualContentType, someHeader}, actualBody] =
    OK(contentType, body, {someHeader: someHeaderValue})

  // then
  console.log('OK returns expected values:')
  console.log('    pathname:', actualStatus === 200 ? 'PASS' : `FAIL: actual was (${actualStatus})`);
  console.log('        body:', actualBody === body ? 'PASS' : `FAIL: actual was (${actualBody})`);
  console.log('content-type:', actualContentType === contentType ? 'PASS' : `FAIL: actual was (${actualContentType})`);
  console.log('  someHeader:', someHeader === someHeaderValue ? 'PASS' : `FAIL: actual was (${someHeader})`);
  console.log();
})();


(() => {
  // given
  let contentType = 'text/plain';
  let body = 'the body';
  let someHeaderValue = 'the value';

  // when
  let [actualStatus, {"Content-Type":actualContentType, someHeader}, actualBody] =
    OK(contentType, body, {'Content-Type': 'application/foo', someHeader: someHeaderValue})

  // then
  console.log('OK contentType overrides other headers:')
  console.log('content-type:', actualContentType === contentType ? 'PASS' : `FAIL: actual was (${actualContentType})`);
  console.log('  someHeader:', someHeader === someHeaderValue ? 'PASS' : `FAIL: actual was (${someHeader})`);
  console.log();
})();

(() => {
  // given
  let requestUnpacker = RequestUnpacker();
  let request = {url: '/bob?target=baz'};

  // when
  let [pathname, target] = requestUnpacker.unpack(request)

  // then
  console.log('RequestUnpacker target passed test: ')
  console.log('    pathname:', pathname === '/bob' ? 'PASS' : `FAIL: actual was (${pathname})`);
  console.log('        body:', target === 'baz' ? 'PASS' : `FAIL: actual was (${target})`);
  console.log();
})();

(() => {
  // given
  let defaultTarget = 'foo'
  let requestUnpacker = RequestUnpacker('foo');
  let request = {url: '/hello'};

  // when
  let [pathname, target] = requestUnpacker.unpack(request)

  // then
  console.log('RequestUnpacker default target test: ')
  console.log('    pathname:', pathname === '/hello' ? 'PASS' : `FAIL: actual was (${pathname})`);
  console.log('        body:', target === defaultTarget ? 'PASS' : `FAIL: actual was (${target})`);
  console.log();
})();

(() => {
  // given
  let dispatcher = Dispatcher({ unpack(req) { return ['/hello', 'foo'] }});

  // when
  let [status, headers, actual] = dispatcher.dispatch(null);

  // then
  console.log('Hello Route test: ')
  console.log('      status:', status === 200 ? 'PASS' : `FAIL: actual was (${status})`);
  console.log('     headers:', headers['Content-Type'] === 'text/plain' ? 'PASS' : `FAIL: actual was (${headers['Content-Type']})`);
  console.log('        body:', actual === 'Hello, foo!' ? 'PASS' : `FAIL: actual was (${actual})`);
  console.log();
})();

(() => {
  // given
  let dispatcher = Dispatcher({ unpack(req) { return ['/length', 'foo'] }});

  // when
  let [status, headers, actual] = dispatcher.dispatch(null);

  // then
  console.log('Length Route test: ')
  console.log('      status:', status === 200 ? 'PASS' : `FAIL: actual was (${status})`);
  console.log('     headers:', headers['Content-Type'] === 'text/plain' ? 'PASS' : `FAIL: actual was (${headers['Content-Type']})`);
  console.log('        body:', actual === '3' ? 'PASS' : `FAIL: actual was (${actual})`);
  console.log();
})();

console.log('Starting server . . .');
http.createServer(wiring()).listen(9405);