Shows differences in koa error handling (for koa #1098)

koa-error-default-vs-custom.js

'use strict';

const
  PORT              = 8080,
  URL_LISTEN        = `http://localhost:${PORT}`,
  ROUTE_DEFAULT     = "/default",
  ROUTE_CUSTOM      = "/custom",
  ROUTE_CUSTOM_CODE = "/custom_code";

const
  request = require("request"),
  Koa     = require("koa"),
  app     = new Koa(),
  route   = require("koa-route"),
  rp      = require("request-promise");

//////////////////////////////////////////////

const
  CODE = 400,
  MSG  = "this is bad";

///////////////////////

const handlerDefault = (ctx) => {
  ctx.assert(false, CODE, MSG);
};

const handlerCustom = (ctx) => {
  try
  {
    ctx.assert(false, CODE, MSG);
  }
  catch (err)
  {
    console.log(`Hit custom error handler, err.status: ${err.status}`);
  }
};

const handlerCustomCode = (ctx) => {
  try
  {
    ctx.assert(false, CODE, MSG);
  }
  catch (err)
  {
    ctx.status = err.status || 500;
    console.log(`Hit custom error handler, ctx.status set to err.status: ${ctx.status}`);
  }
};

///////////////////////

app.use(route.get(ROUTE_DEFAULT    , handlerDefault));
app.use(route.get(ROUTE_CUSTOM     , handlerCustom));
app.use(route.get(ROUTE_CUSTOM_CODE, handlerCustomCode));

app.listen(PORT);

///////////////////////

async function req(url)
{
  try { await rp(url); }
  catch (err)
  {
    console.error(`Request failed with HTTP response code ${err.statusCode}\n`);
  }
}

async function main()
{
  await req(`${URL_LISTEN}${ROUTE_DEFAULT}`);
  await req(`${URL_LISTEN}${ROUTE_CUSTOM}`);
  await req(`${URL_LISTEN}${ROUTE_CUSTOM_CODE}`);

  process.exit(0);
}

main().then().catch(console.error);